Types of Weightloss Diets
| Vegetarian Diet | Atkins Diet | |||
| Vegan Diet | Very Low Calorie Diet | |||
| Meditarrean Diet | Zone Diet | |||
| Kusher | Kangaroo Diet |
A well-planned vegetarian diet is a healthy way to meet your nutritional needs. Find out what you need to know about a plant-based diet.
Vegetarian diets continue to increase in popularity. Reasons for following a vegetarian diet are varied but include health benefits, such as reducing your risk of heart disease, diabetes and some cancers.
Yet some vegetarians rely too heavily on processed foods, which can be high in calories, sugar, fat and sodium. And they may not eat enough fruits, vegetables, whole grains and calcium-rich foods, thus missing out on the nutrients they provide.
However, with a little planning a vegetarian diet can meet the needs of people of all ages, including children, teenagers, and pregnant or breast-feeding women. The key is to be aware of your nutritional needs so that you plan a diet that meets them.
When people think about a vegetarian diet, they typically think about a diet that doesn't include meat, poultry or fish. But vegetarian diets vary in what foods they include and exclude:
Lacto-vegetarian diets exclude meat, fish, poultry and eggs, as well as foods that contain them. Dairy products, such as milk, cheese, yogurt and butter, are included.
Ovo-vegetarian diets exclude meat, poultry, seafood and dairy products, but allow eggs.
Lacto-ovo vegetarian diets exclude meat, fish and poultry, but allow dairy products and eggs.
Pescatarian diets exclude meat and poultry, dairy, and eggs, but allow fish.
Vegan diets exclude meat, poultry, fish, eggs and dairy products — and foods that contain these products.
Some people follow a semivegetarian diet — also called a flexitarian diet — which is primarily a plant-based diet but includes meat, dairy, eggs, poultry and fish on occasion or in small quantities.
To get the most out of a vegetarian diet, choose a variety of healthy plant-based foods, such as whole fruits and vegetables, legumes and nuts, and whole grains. At the same time, cut back on less healthy choices, such as sugar-sweetened beverages, fruit juices and refined grains. If you need help, a registered dietitian can assist you in creating a vegetarian plan that's right for you.
|
Food group |
Recommended servings for 2,000-calorie/day diet |
|---|---|
|
Source: 2015-2020 Dietary Guidelines for Americans |
|
|
Vegetables |
2 1/2 cups a day |
|
Dark green |
1 1/2 cups a week |
|
Red and orange |
5 1/2 cups a week |
|
Legumes (beans and peas) |
1 1/2 cups a week |
|
Starchy |
5 cups a week |
|
Other |
4 cups a week |
|
Fruits |
2 cups a day |
|
Grains |
6 1/2 ounces a day |
|
Whole grains |
≥ 3 1/2 ounces a day |
|
Refined grains |
≤ 3 ounces a day |
|
Dairy |
3 cups a day |
|
Protein foods |
3 1/2 ounces a day |
|
Eggs |
3 ounces a week |
|
Legumes (beans and peas) |
6 cups a week |
|
Soy products |
7 ounces a week |
|
Nuts and seeds |
8 ounces a week |
|
Oils |
27 grams a day |
|
Added sugars, solid fats, added refined starches |
No more than 290 calories a day (15% of total calories) |
Keep in mind that the more restrictive your diet is, the more challenging it can be to get all the nutrients you need. A vegan diet, for example, eliminates natural food sources of vitamin B-12, as well as milk products, which are good sources of calcium.
To be sure that your diet includes everything your body needs, pay special attention to the following nutrients:
Calcium helps build and maintain strong teeth and bones. Milk and dairy foods are highest in calcium. However, dark green vegetables, such as turnip and collard greens, kale, and broccoli, are good plant sources when eaten in sufficient quantities. Calcium-enriched and fortified products, including juices, cereals, soy milk, soy yogurt and tofu, are other options.
Vitamin D also plays an important role in bone health. Vitamin D is added to cow's milk, some brands of soy and rice milk, and some cereals and margarines. Be sure to check food labels. If you don't eat enough fortified foods and have limited sun exposure, you may need a vitamin D supplement (one derived from plants).
Vitamin B-12 is necessary to produce red blood cells and prevent anemia. This vitamin is found almost exclusively in animal products, so it can be difficult to get enough B-12 on a vegan diet. Vitamin B-12 deficiency may go undetected in people who eat a vegan diet. This is because the vegan diet is rich in a vitamin called folate, which may mask deficiency in vitamin B-12 until severe problems occur. For this reason, it's important for vegans to consider vitamin supplements, vitamin-enriched cereals and fortified soy products.
Protein helps maintain healthy skin, bones, muscles and organs. Eggs and dairy products are good sources, and you don't need to eat large amounts to meet your protein needs. You can also get sufficient protein from plant-based foods if you eat a variety of them throughout the day. Plant sources include soy products and meat substitutes, legumes, lentils, nuts, seeds, and whole grains.
Omega-3 fatty acids are important for heart health. Diets that do not include fish and eggs are generally low in active forms of omega-3 fatty acids. Canola oil, soy oil, walnuts, ground flaxseed and soybeans are good sources of essential fatty acids. However, because conversion of plant-based omega-3 to the types used by humans is inefficient, you may want to consider fortified products or supplements or both.
Iron is a crucial component of red blood cells. Dried beans and peas, lentils, enriched cereals, whole-grain products, dark leafy green vegetables, and dried fruit are good sources of iron. Because iron isn't as easily absorbed from plant sources, the recommended intake of iron for vegetarians is almost double that recommended for nonvegetarians. To help your body absorb iron, eat foods rich in vitamin C, such as strawberries, citrus fruits, tomatoes, cabbage and broccoli, at the same time as you're eating iron-containing foods.
Like iron, zinc is not as easily absorbed from plant sources as it is from animal products. Cheese is a good option if you eat dairy products. Plant sources of zinc include whole grains, soy products, legumes, nuts and wheat germ. Zinc is an essential component of many enzymes and plays a role in cell division and in formation of proteins.
Iodine is a component in thyroid hormones, which help regulate metabolism, growth and function of key organs. Vegans may not get enough iodine and may be at risk of deficiency and possibly even a goiter. In addition, foods such as soybeans, cruciferous vegetables and sweet potatoes may promote a goiter. However, just 1/4 teaspoon of iodized salt a day provides a significant amount of iodine.
One way to transition to a vegetarian diet is to gradually reduce the meat in your diet while increasing fruits and vegetables. Here are a couple of tips to help you get started:
Ramp up. Each week increase the number of meatless meals you already enjoy, such as spaghetti with tomato sauce or vegetable stir-fry. Find ways to include greens, such as spinach, kale, Swiss chard and collards, in your daily meals.
Substitute. Take favorite recipes and try them without meat. For example, make vegetarian chili by leaving out the ground beef and adding an extra can of black beans. Or make fajitas using extra-firm tofu rather than chicken. You may be surprised to find that many dishes require only simple substitutions.
Branch out. Check the internet for vegetarian menus. Buy or borrow vegetarian cookbooks. Check out ethnic restaurants to sample new vegetarian cuisines. The more variety you bring to your vegetarian diet, the more likely you'll be to meet all your nutritional needs.
Vegetarians do not eat meat, fish, or poultry. Vegans, in addition to being vegetarian, do not use other animal products and by-products such as eggs, dairy products, honey, leather, fur, silk, wool, cosmetics, and soaps derived from animal products.
People choose to be vegan for health, environmental, and/or ethical reasons. For example, some vegans feel that one promotes the meat industry by consuming eggs and dairy products. That is, once dairy cows or egg-laying chickens are too old to be productive, they are often sold as meat; and since male calves do not produce milk, they usually are raised for veal or other products. Some people avoid these items because of conditions associated with their production.
Many vegans choose this lifestyle to promote a more humane and caring world. They know they are not perfect, but believe they have a responsibility to try to do their best, while not being judgmental of others.
The key to a nutritionally sound vegan diet is variety. A healthy and varied vegan diet includes fruits, vegetables, plenty of leafy greens, whole grain products, nuts, seeds, and legumes.
It is very easy for a vegan diet to meet the recommendations for protein as long as calorie intake is adequate. Strict protein planning or combining is not necessary. The key is to eat a varied diet.
Almost all foods except for alcohol, sugar, and fats provide some protein. Vegan sources include: lentils, chickpeas, tofu, peas, peanut butter, soy milk, almonds, spinach, rice, whole wheat bread, potatoes, broccoli, kale...
|
Here Are Some Sample Menus Showing How Easy It Is To Meet Protein Needs |
||
|
Protein (grams) |
||
|
Breakfast: |
1 cup Oatmeal |
6 |
|
|
1 cup Soy Milk |
7 |
|
|
1 medium Bagel |
10 |
|
Lunch: |
2 slices Whole Wheat Bread |
7 |
|
|
1 cup Vegetarian Baked Beans |
12 |
|
Dinner: |
5 oz firm Tofu |
12 |
|
|
1 cup cooked Broccoli |
4 |
|
|
1 cup cooked Brown Rice |
5 |
|
|
2 Tbsp Almonds |
4 |
|
Snack: |
2 Tbsp Peanut Butter |
8 |
|
|
6 Crackers |
2 |
|
TOTAL |
|
77 grams |
|
Protein Recommendation for Male Vegan |
63 grams |
|
|
[based on 0.9 gram of protein per kilogram body weight for 70 kilogram (154 pound) male] |
||
|
|
||
|
Breakfast: |
2 slices Whole Wheat Toast |
7 |
|
|
2 Tbsp Peanut Butter |
8 |
|
Lunch: |
6 oz Soy Yogurt |
6 |
|
|
2 Tbsp Almonds |
4 |
|
|
1 medium Baked Potato |
3 |
|
Dinner: |
1 cup cooked Lentils |
18 |
|
|
1 cup cooked Bulgur |
6 |
|
Snack: |
1 cup Soy Milk |
7 |
|
TOTAL |
|
59 grams |
|
Protein Recommendation for Female Vegan |
52 grams |
|
|
[based on 0.9 gram of protein per kilogram body weight for 57.5 kilogram (126 pound) female] |
||
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Additional food should be added to these menus to provide adequate calories and to meet requirements for nutrients besides protein. |
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Vegan diets are free of cholesterol and are generally low in saturated fat. Thus eating a vegan diet makes it easy to conform to recommendations given to reduce the risk of major chronic diseases such as heart disease and cancer. High-fat foods, which should be used sparingly, include oils, margarine, nuts, nut butters, seed butters, avocado, and coconut.
Vitamin D is not found in the vegan diet but can be made by humans following exposure to sunlight. At least ten to fifteen minutes of summer sun on hands and face two to three times a week is recommended for adults so that vitamin D production can occur. Food sources of vitamin D include vitamin D-fortified soy milk and rice milk. (For more information about vitamin D, see FAQs About Vitamin D)
Calcium, needed for strong bones, is found in dark green vegetables, tofu made with calcium sulfate, calcium-fortified soy milk and orange juice, and many other foods commonly eaten by vegans. Although lower animal protein intake may reduce calcium losses, there is currently not enough evidence to suggest that vegans have lower calcium needs. Vegans should eat foods that are high in calcium and/or use a calcium supplement.
Following are some good sources of calcium:
|
Soy or rice milk, |
8 oz |
200-300 mg |
|
Collard greens, cooked |
1 cup |
357 mg |
|
Blackstrap molasses |
2 TB |
400 mg |
|
Tofu, processed with calcium sulfate |
4 oz |
200-330 mg |
|
Calcium-fortified orange juice |
8 oz |
300 mg |
|
Tofu, processed with nigari |
4 oz |
80-230 mg |
|
Kale, cooked |
1 cup |
179 mg |
|
Tahini |
2 TB |
128 mg |
|
Almonds |
¼ cup |
89 mg |
Other good sources of calcium include: okra, turnip greens, soybeans, tempeh, almond butter, broccoli, bok choy, commercial soy yogurt...
The recommended intake for calcium for adults 19 through 50 years is 1000 milligrams/day.
Note: It appears that oxalic acid, which is found in spinach, rhubarb, chard, and beet greens, binds with calcium and reduces calcium absorption. Calcium is well absorbed from other dark green vegetables.
Vegan diets can provide zinc at levels close to or even higher than the RDA. Zinc is found in grains, legumes, and nuts.
Dried beans and dark green leafy vegetables are especially good sources of iron, better on a per calorie basis than meat. Iron absorption is increased markedly by eating foods containing vitamin C along with foods containing iron.
Soybeans, lentils, blackstrap molasses, kidney beans, chickpeas, black-eyed peas, Swiss chard, tempeh, black beans, prune juice, beet greens, tahini, peas, bulghur, bok choy, raisins, watermelon, millet, kale....
Here are the iron contents of selected foods:
______________________________________________
FOOD IRON (MG)
______________________________________________
1 cup cooked soybeans 8.8
2 Tbsp blackstrap molasses 7.0
1 cup cooked lentils 6.6
1 cup cooked kidney beans 5.2
1 cup cooked chickpeas 4.7
1 cup cooked lima beans 4.5
1 cup cooked Swiss chard 4.0
1/8 medium watermelon 1.0
______________________________________________
In order to maximize production of DHA and EPA (omega-3 fatty acids), vegans should include good sources of alpha-linolenic acid in their diets such as flaxseed, flaxseed oil, canola oil, tofu, soybeans, and walnuts.
The requirement for vitamin B12 is very low. Non-animal sources include Red Star nutritional yeast T6635 also known as Vegetarian Support Formula (around 2 teaspoons supplies the adult RDA). It is especially important for pregnant and lactating women, infants, and children to have reliable sources of vitamin B12 in their diets. Numerous foods are fortified with B12, but sometimes companies change what they do. So always read labels carefully or write the companies.
Tempeh, miso, and seaweed are often labeled as having large amounts of vitamin B12. However, these products are not reliable sources of the vitamin because the amount of vitamin B12 present depends on the type of processing the food undergoes. Other sources of vitamin B12 are fortified soy milk (check the label as this is rarely available in the U.S.), vitamin B12-fortified meat analogues, and vitamin B12 supplements. There are supplements which do not contain animal products. Vegetarians who are not vegan can also obtain vitamin B12 from dairy products and eggs.
Oatmeal, stir-fried vegetables, cereal, toast, orange juice, peanut butter on whole wheat bread, frozen fruit desserts, lentil soup, salad bar items like chickpeas and three bean salad, dates, apples, macaroni, fruit smoothies, popcorn, spaghetti, vegetarian baked beans, guacamole, chili...
Tofu lasagna, homemade pancakes without eggs, hummus, eggless cookies, soy ice cream, tempeh, corn chowder, soy yogurt, rice pudding, fava beans, banana muffins, spinach pies, oat nut burgers, falafel, corn fritters, French toast made with soy milk, soy hot dogs, vegetable burgers, pumpkin casserole, scrambled tofu, seitan.
Pizza without cheese, Chinese moo shu vegetables, Indian curries and dal, eggplant dishes without the cheese, bean tacos without the lard and cheese (available from Taco Bell and other Mexican restaurants), Middle Eastern hummus and tabouli, Ethiopian injera (flat bread) and lentil stew, Thai vegetable curries...
As a binder, substitute for each egg:
1/4 cup (2 ounces) soft tofu blended with the liquid ingredients of the recipe, or
1 small banana, mashed, or
1/4 cup applesauce, or
2 tablespoons cornstarch or arrowroot starch, or Ener-G Egg Replacer or another commercial mix found in health food stores.
The following substitutions can be made for dairy products:
Soy milk, rice milk, potato milk, nut milk, or water (in some recipes) may be used.
Buttermilk can be replaced with soured soy or rice milk. For each Cup of buttermilk, use 1 cup soymilk plus 1 tablespoon of vinegar.
Soy cheese available in health food stores. (Be aware that many soy cheeses contain casein, which is a dairy product.)
Crumbled tofu can be substituted for cottage cheese or ricotta cheese in lasagna and similar dishes.
Several brands of nondairy cream cheese are available in some supermarkets and kosher stores.
VRG Articles
Other Articles
Order Simply Vegan for a complete discussion of vegan nutrition plus 160 quick and easy recipes. This excellent resource contains over 160 vegan recipes that can be prepared quickly. An extensive vegan nutrition section by Reed Mangels, Ph.D., R.D., covers topics such as protein, fat, calcium, iron, vitamin B12, pregnancy and the vegan diet, feeding vegan kids, weight gain, weight loss, and a nutrition glossary. Also featured are sample menus and meal plans. Simply Vegan is more than a cookbook. An additional section on shopping by mail tells you where to find vegan clothes, non-leather shoes, cosmetics, household products, and books.
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Vegans Know How to Party by Chef Nancy Berkoff, RD |
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Simply Vegan by Debra Wasserman. Nutrition section by Reed Mangels Ph.D., R.D. |
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Conveniently Vegan by Debra Wasserman |
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Vegan Handbook Edited by Debra Wasserman and Reed Mangels Ph.D., R.D. |
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The Lowfat Jewish Vegetarian Cookbook by Debra Wasserman |
For more information, Subscribe to the Vegetarian Journal.
The contents of this brochure and our other publications are not intended to provide personal medical advice. Medical advice should be obtained from a qualified health professional.
This electronic edition of the brochure, "Veganism In a Nutshell" is published by:
The Vegetarian Resource Group
PO Box 1463
Baltimore, MD 21203
(410) 366-VEGE
email: vrg@vrg.org
Our health professionals, activists, and educators work with businesses and individuals to bring about healthy changes in your school, workplace, and community. Registered dietitians and physicians aid in the development of nutrition-related publications and answer member and media questions about vegetarian diets. The Vegetarian Resource Group is a non-profit organization. Financial support comes primarily from memberships, contributions, and book sales.
Very Low-Calorie Diets and Superfood
Very Low-Calorie Diets
A very low-calorie diet (VLCD) is not just any diet that is low in calories. It is a special type of diet that replaces all of your meals with prepared formulas, often in the form of liquid shakes.
A VLCD may be used for a short time to promote quick weight loss among some people who are considered to be obese. The diet requires close care from your doctor and is usually combined with other ways to lose weight (see How is obesity treated? below).
This fact sheet will tell you more about the risks and benefits of this type of diet. Do not go on a VLCD on your own. If you need to lose weight, talk to your health care provider about the approaches that may work best for you.
What is a VLCD?
A VLCD is a special diet that provides up to 800 calories per day. VLCDs use commercial formulas, usually liquid shakes, soups, or bars, which replace all your regular meals. These formulas are not the same as the meal replacements you can find at grocerystores or pharmacies, which are meant to replace one or two meals a day.
Depending on a number of factors, healthy adults need different amounts of calories to meet their daily energy needs. A standard amount is about 2,000 calories. VLCDs provide far fewer calories than most people need to maintain a healthy weight. This type of diet is used to promote quick weight loss, often as a way to jump-start an obesity treatment program.
VLCD formulas are designed to provide all of the nutrients you need while helping you lose weight quickly. However, this type of diet should only be used for a short time—usually about 12 weeks.
Should I use a VLCD to lose weight?
The Low-calorie Diet (LCD)
An LCD limits calories, but not as much as a VLCD. A typical LCD may provide
1,000–1,200 calories/day for a woman
1,200–1,600 calories/day for a man
The number of calories may be adjusted based on your age, weight, and how active you are. An LCD usually consists of regular foods, but could also include meal replacements. As a result, you may find this type of diet much easier to follow than a VLCD. In the long term, LCDs have been found to lead to the same amount of weight loss as VLCDs.
Most people who need to lose weight should not use a VLCD. For many of them, a low-calorie diet (LCD) may work better (see The Low-calorie Diet (LCD)).
VLCDs may be used to promote rapid weight loss among adults who have obesity. Health care providers must review risks and benefits on a case-by-case basis.
In general, VLCDs are not appropriate for children. In a few cases, they may be used with some adolescents who are being treated for obesity.
Not much is known about the use of VLCDs to promote weight loss among older adults. Some people over age 50 may have medical issues that may not make them good candidates for this type of diet.
What are the health benefits of a VLCD?
A VLCD may allow you to lose about 3 to 5 pounds per week. Th is may lead to an average total weight loss of 44 pounds over 12 weeks. Such a weight loss can rapidly improve medical conditions linked to obesity, including diabetes, high blood pressure, and high cholesterol.
The rapid weight loss experienced by most people on a VLCD can be very motivating. Patients who participate in a VLCD program that also includes lifestyle changes may lose about 15 to 25 percent of their initial weight during the first 3 to 6 months. They may maintain a 5 percent weight loss after 4 years if they adopt a healthy eating plan and physical activity habits.
What are the health risks of a VLCD?
Doctors must monitor all VLCD patients regularly—ideally every 2 weeks in the initial period of rapid weight loss—to be sure patients are not experiencing serious side effects.
Many patients on a VLCD for 4 to 16 weeks report minor side effects such as fatigue, constipation, nausea, or diarrhea. These conditions usually improve within a few weeks and rarely prevent patients from completing the program.
The most common serious side effect is gallstones. Gallstones, which often develop in people who are obese, especially women, may be even more commonly developed during rapid weight loss. Some medicines can prevent gallstones from forming during rapid weight loss. Your health care provider can determine if these medicines are appropriate for you. For more information, see the WIN fact sheet on dieting and gallstones, listed under Resources.
Will I regain the weight?
Although the long-term results of VLCDs vary widely, weight regain is common. To prevent weight regain, the VLCD should always be combined with other ways to lose weight and with an active follow-up program.
For most people who have obesity, the condition is long term and requires a lifetime of attention even after formal methods to treat the obesity end. You may need to commit to permanent changes of healthier eating, regular physical activity, and an improved outlook about food.
How is obesity treated?
Obesity is treated using one or more of these strategies:
a diet low in calories
increased physical activity
behavior therapy
prescription medications
weight-loss surgery
Research
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducts and supports a broad range of basic and clinical obesity research. More information about obesity research is available at http://www.obesityresearch.nih.govExternal NIH Link.
Clinical trials are research studies involving people. Clinical trials look at safe and effective new ways to prevent, detect, or treat disease. Researchers also use clinical trials to look at other aspects of care, such as improving the quality of life for people with chronic illnesses. To learn more about clinical trials, why they matter, and how to participate, visit the NIH Clinical Research Trials and You website at http://www.nih.gov/health/clinicaltrials?External NIH Link.For information about current studies, visit http://www.ClinicalTrials.govExternal Link Disclaimer.
Resources
Additional Reading
Active at Any Size!
Contains information designed to encourage black women to move more and eat better.
Better Health and You: Tips for Adults
Provides tips for adults on how to eat better and be more active.?
Choosing a Safe and Successful Weight-loss Program
Provides tips on how to identify a weight-loss program that helps with losing weight safely, keeping the weight off over time and discussing weight with health care providers.
Dieting and Gallstones
Describes gallstones, the effect of overweight and dieting on risk and safe ways to lose weight to reduce risk.
2008 Physical Activity Guidelines for Americans
http://www.health.gov/paguidelines/guidelinesExternal Link Disclaimer
Dietary Guidelines for Americans, 2010
http://health.gov/dietaryguidelinesExternal Link Disclaimer
National Diabetes Education Program
http://yourdiabetesinfo.orgExternal Link Disclaimer
Inclusion of resources is for information only and does not imply endorsement by NIDDK or WIN.?
NIH Publication No. 03–3894
August 2008
Updated December 2012?????
NIDDK
Super Foods/ Super Diets
Super Foods are a component of the Balanced Choices program and will highlight foods that promote health benefits above and beyond the basic nutrients. These documents are all printer-friendly PDF (
) files.
Spotlight: Cranberry
Kiwi
Whole Grains
Tomato
Berries
Avocado
Leafy Greens
Herbs & Spices
Nuts
Cranberries
Fish
Apples
Stone Fruits
Tea
Yogurt
Legumes
Dark Chocolate
Updated December 2012
Source: NIDDK, NIH
Written by Adda Bjarnadottir, MS on January 3, 2019 (From Healthline)
There are many weight loss diets out there.
Some focus on reducing your appetite, while others restrict calories, carbs, or fat.
Since all of them claim to be superior, it can be hard to know which ones are worth trying.
The truth is that no one diet is best for everyone — and what works for you may not work for someone else.
This article reviews the 9 most popular weight loss diets and the science behind them.
The paleo diet claims that you should eat the same foods that your hunter-gatherer ancestors ate before agriculture developed.
The theory is that most modern diseases can be linked to the Western diet and the consumption of grains, dairy, and processed foods.
While it's debatable whether this diet really provides the same foods your ancestors ate, it is linked to several impressive health benefits.
How it works: The paleo diet emphasizes whole foods, lean protein, vegetables, fruits, nuts, and seeds, while discouraging processed foods, sugar, dairy, and grains.
Some more flexible versions of the paleo diet also allow for dairy like cheese and butter, as well as tubers like potatoes and sweet potatoes.
Weight loss: Several studies have shown that the paleo diet can lead to significant weight loss and reduced waist size.
In studies, paleo dieters automatically eat much fewer carbs, more protein, and 300–900 fewer calories per day.
Other benefits: The diet seems effective at reducing risk factors for heart disease, such as cholesterol, blood sugar, blood triglycerides, and blood pressure.
The downside: The paleo diet eliminates whole grains, legumes, and dairy, which are healthy and nutritious.
SUMMARY The paleo diet emphasizes whole foods but bans grains and dairy. Its multiple health benefits include weight loss.
The vegan diet restricts all animal products for ethical, environmental, or health reasons.
Veganism is also associated with resistance to animal exploitation and cruelty.
How it works: Veganism is the strictest form of vegetarianism.
In addition to eliminating meat, it eliminates dairy, eggs, and animal-derived products, such as gelatin, honey, albumin, whey, casein, and some forms of vitamin D3.
Weight loss: A vegan diet seems to be very effective at helping people lose weight — often without counting calories — because its very low fat and high fiber content may make you feel fuller for longer.
Vegan diets are consistently linked to lower body weight and body mass index (BMI) compared to other diets.
One 18-week study showed that people on a vegan diet lost 9.3 pounds (4.2 kg) more than those on a control diet. The vegan group was allowed to eat until fullness, but the control group had to restrict calories.
However, calorie for calorie, vegan diets are not more effective for weight loss than other diets.
Weight loss on vegan diets is primarily associated with reduced calorie intake.
Other benefits: Plant-based diets are linked to a reduced risk of heart disease, type 2 diabetes, and premature death.
Limiting processed meat may also reduce your risk of Alzheimer's disease and dying from heart disease or cancer.
The downside: Because vegan diets eliminate animal foods completely, they may be low in several nutrients, including vitamin B12, vitamin D, iodine, iron, calcium, zinc, and omega-3 fatty acids.
SUMMARY Vegan diets exclude all animal products. They may cause weight loss due to lower calorie intake while reducing your risk of several diseases.
Low-carb diets have been popular for decades — especially for weight loss.
There are several types of low-carb diets, but all involve limiting carb intake to 20–150 grams per day.
The primary aim of the diet is to force your body to use more fats for fuel instead of using carbs as a main source of energy.
How it works: Low-carb diets emphasize unlimited amounts of protein and fat while severely limiting your carb intake.
When carb intake is very low, fatty acids are moved into your blood and transported to your liver, where some of them are turned into ketones.
Your body can then use fatty acids and ketones in the absence of carbs as its primary energy source.
Weight loss: Numerous studies indicate that low-carb diets are extremely helpful for weight loss, especially in overweight and obese individuals).
They seem to be very effective at reducing dangerous belly fat, which can become lodged around your organs.
People on very low-carb diets commonly reach a state called ketosis. Many studies note that ketogenic diets lead to more than twice the weight loss than a low-fat, calorie-restricted diet.
Other benefits: Low-carb diets tend to reduce your appetite and make you feel less hungry, leading to an automatic reduction in calorie intake.
Furthermore, low-carb diets may benefit many major disease risk factors, such as blood triglycerides, cholesterol levels, blood sugar levels, insulin levels, and blood pressure.
The downside: Low-carb diets do not suit everyone. Some feel great on them while others feel miserable.
Some people may experience an increase in “bad” LDL cholesterol.
In extremely rare cases, very low-carb diets can cause a serious condition called ketoacidosis. This condition seems to be more common in lactating women and can be fatal if left untreated.
However, low-carb diets are safe for the majority of people.
SUMMARY Low-carb diets severely limit carb intake and push your body to use fat for fuel. They aid weight loss and are linked to many other health benefits.
The Dukan diet is a high-protein, low-carb weight loss diet split into four phases — two weight loss phases and two maintenance phases.
How long you stay in each phase depends on how much weight you need to lose. Each phase has its own dietary pattern.
How it works: The weight loss phases are primarily based on eating unlimited high-protein foods and mandatory oat bran.
The other phases involve adding non-starchy vegetables followed by some carbs and fat. Later on, there will be fewer and fewer pure protein days to maintain your new weight.
Weight loss: In one study, women following the Dukan diet ate about 1,000 calories and 100 grams of protein per day and lost an average of 33 pounds (15 kg) in 8–10 weeks.
Also, many other studies show that high-protein, low-carb diets may have major weight loss benefits.
These include a higher metabolic rate, a decrease in the hunger hormone ghrelin and an increase in several fullness hormones.
Other benefits: Apart from weight loss, there are no recorded benefits of the Dukan diet in scientific literature.
The downside: There is very little quality research available on the Dukan diet.
The Dukan diet limits both fat and carbs — a strategy not based on science. On the contrary, consuming fat as part of a high-protein diet seems to increase metabolic rate compared to both low-carb and low-fat diets.
What’s more, fast weight loss achieved by severe calorie restriction tends to cause significant muscle loss.
The loss of muscle mass and severe calorie restriction may also cause your body to conserve energy, making it very easy to regain the weight after losing it.
SUMMARY The Dukan diet has not been tested in quality human studies. The diet may cause weight loss, but it also may slow down your metabolism and make you lose muscle mass along with fat mass.
An ultra-low-fat diet restricts your consumption of fat to under 10% of daily calories.
Generally, a low-fat diet provides around 30% of its calories as fat.
Studies reveal that this diet is ineffective for weight loss in the long term.
Proponents of the ultra-low-fat diet claim that traditional low-fat diets are not low enough in fat and that fat intake needs to stay under 10% of total calories to produce health benefits and weight loss.
How it works: An ultra-low-fat diet contains 10% or fewer calories from fat. The diet is mostly plant-based and has a limited intake of animal products.
Therefore, it's generally very high in carbs — around 80% of calories — and low in protein — at 10% of calories.
Weight loss: This diet has proven very successful for weight loss among obese individuals. In one study, obese individuals lost an average of 140 pounds (63 kg) on an ultra-low-fat diet.
Another 8-week study with a diet containing 7–14% fat showed an average weight loss of 14.8 pounds (6.7 kg).
Other benefits: Studies suggest that ultra-low-fat diets can improve several risk factors for heart disease, including high blood pressure, high cholesterol, and markers of inflammation.
Surprisingly, this high-carb, low-fat diet can also lead to significant improvements in type 2 diabetes.
Furthermore, it may slow the progression of multiple sclerosis — an autoimmune disease that affects your brain, spinal cord, and optic nerves in the eyes.
The downside: The fat restriction may cause long-term problems, as fat plays many important roles in your body. These include helping build cell membranes and hormones, as well as helping your body absorb fat-soluble vitamins.
Moreover, an ultra-low-fat diet limits intake of many healthy foods, lacks variety, and is extremely hard to stick to.
SUMMARY An ultra-low-fat diet contains less than 10% of its calories from fat. It can cause significant weight loss and may also have impressive benefits for heart disease, type 2 diabetes, and multiple sclerosis.
The Atkins diet is the most well-known low-carb weight loss diet.
Its proponents insist that you can lose weight by eating as much protein and fat as you like, as long as you avoid carbs.
The main reason why low-carb diets are so effective for weight loss is that they reduce your appetite.
This causes you to eat fewer calories without having to think about it.
How it works: The Atkins diet is split into four phases. It starts with an induction phase, during which you eat under 20 grams of carbs per day for two weeks.
The other phases involve slowly reintroducing healthy carbs back into your diet as you approach your goal weight.
Weight loss: The Atkins diet has been studied extensively and found to lead to faster weight loss than low-fat diets.
Other studies note that low-carb diets are very helpful for weight loss. They are especially successful in reducing belly fat, the most dangerous fat that lodges itself in your abdominal cavity.
Other benefits: Numerous studies show that low-carb diets, like the Atkins diet, may reduce many risk factors for disease, including blood triglycerides, cholesterol, blood sugar, insulin, and blood pressure.
Compared to other weight loss diets, low-carb diets also better improve blood sugar, “good” HDL cholesterol, triglycerides, and other health markers.
The downside: As do other very low-carb diets, the Atkins diet is safe and healthy for most people but may cause problems in rare cases.
SUMMARY The Atkins diet is a low-carb weight loss diet. It's effective for weight loss but also has benefits for many other disease risk factors.
The HCG diet is an extreme diet meant to cause very fast weight loss of up to 1–2 pounds (0.45–1 kg) per day.
Its proponents claim that it boosts metabolism and fat loss without inducing hunger.
HCG (human chorionic gonadotropin) is a hormone present at high levels during early pregnancy.
It tells a woman's body it's pregnant and maintains the production of hormones that are important for fetal development. It has also been used to treat fertility issues.
How it works: The diet is split into three phases. During the first phase, you begin taking HCG supplements.
During the second phase, you follow an ultra-low-calorie diet of only 500 calories per day, along with HCG supplement drops, pellets, injections, or sprays. The weight loss phase is prescribed for 3–6 weeks at a time.
In the third phase, you stop taking HCG and slowly increase your food intake.
Weight loss: The HCG diet does cause weight loss, but multiple studies conclude that the weight loss is due to the ultra-low-calorie diet alone — not the HCG hormone.
Furthermore, HCG was not found to reduce hunger.
Other benefits: Aside from weight loss, there are no documented benefits of the HCG diet.
The downside: Like most other ultra-low-calorie diets, the HCG diet may cause muscle loss, which results in a reduced ability to burn calories.
Such severe calorie restriction further reduces the number of calories your body burns. This is because your body thinks it's starving and therefore attempts to preserve energy.
In addition, most HCG products on the market are scams and don't contain any HCG. Only injections are able to raise blood levels of this hormone.
Moreover, the diet has many side effects, including headaches, fatigue, and depression. There is also one report of a woman developing blood clots, most likely caused by the diet.
The FDA disapproves of this diet, labeling it dangerous, illegal, and fraudulent.
SUMMARY The HCG diet is a rapid weight loss diet. It's not based on any scientific evidence and may reduce metabolic rate and cause muscle loss, headaches, fatigue, and depression.
The Zone Diet is a low-glycemic load diet that has you limit carbs to 35–45% of daily calories and protein and fat to 30% each.
It recommends eating only carbs with a low glycemic index (GI).
The GI of a food is an estimate of how much it raises your blood glucose levels after consumption.
The Zone Diet was initially developed to reduce diet-induced inflammation, cause weight loss, and reduce your risk of chronic diseases.
How it works: The Zone Diet recommends balancing each meal with 1/3 protein, 2/3 colorful fruits and veggies, and a dash of fat — namely monounsaturated oil, such as olive oil, avocado, or almonds.
It also limits high-GI carbs, such as bananas, rice, and potatoes.
Weight loss: Studies on low-GI diets are rather inconsistent. While some say that the diet promotes weight loss and reduces appetite, others show very little weight loss compared to other diets.
Other benefits: The greatest benefit of this diet is a reduction in risk factors for heart disease, such as reduced cholesterol and triglycerides.
One study suggests that the Zone Diet may improve blood sugar control, reduce waist circumference, and lower chronic inflammation in overweight or obese individuals with type 2 diabetes.
The downside: One of the few drawbacks of this diet is that it limits the consumption of some healthy carb sources, such as bananas and potatoes.
SUMMARY The Zone Diet is a low-GI diet. Studies on its weight loss benefits are inconsistent, but the diet improves many important health markers and reduces your risk of heart disease.
Intermittent fasting cycles your body between periods of fasting and eating.
Rather than restricting the foods you eat, it controls when you eat them. Thus, it can be seen as more of an eating pattern than a diet.
The most popular ways to do intermittent fasting are:
The 16/8 method: Involves skipping breakfast and restricting your daily eating period to eight hours, subsequently fasting for the remaining 16 hours of the day.
The eat-stop-eat method: Involves 24-hour fasts once or twice per week on non-consecutive days.
The 5:2 diet: On two non-consecutive days of the week, you restrict your intake to 500–600 calories. You do not restrict intake on the five remaining days.
The Warrior Diet: Eat small amounts of raw fruits and vegetables during the day and one huge meal at night.
How it works: Intermittent fasting is commonly used for weight loss because it leads to relatively easy calorie restriction.
It can make you eat fewer calories overall — as long as you don't overcompensate by eating much more during the eating periods.
Weight loss: Intermittent fasting is generally very successful for weight loss. It has been shown to cause weight loss of 3–8% over a period of 3–24 weeks, which is a lot compared to most weight loss diets.
In addition to causing less muscle loss than standard calorie restriction, it may increase your metabolic rate by 3.6–14% in the short term.
Other benefits: Intermittent fasting may reduce markers of inflammation, cholesterol levels, blood triglycerides, and blood sugar levels.
Furthermore, intermittent fasting has been linked to increased levels of human growth hormone (HGH), improved insulin sensitivity, improved cellular repair, and altered gene expressions.
Animal studies also suggest that it may help new brain cells grow, lengthen lifespan, and protect against Alzheimer's disease and cancer.
The downside: Although intermittent fasting is safe for well-nourished and healthy people, it does not suit everyone.
Some studies note that it's not as beneficial for women as it is for men.
In addition, some people should avoid fasting, including those sensitive to drops in blood sugar levels, pregnant women, breastfeeding moms, teenagers, children, and people who are malnourished, underweight, or nutrient deficient.
SUMMARY Intermittent fasting lets your body cycle between fasting and eating. It is very effective for weight loss and has been linked to numerous health benefits.
There is no perfect weight loss diet.
Different diets work for different people, and you should pick one that suits your lifestyle and tastes.
The best diet for you is the one that you can stick to in the long term.
Ketogenic diet
Testing for ketone bodies in urine
The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used primarily to treat difficult-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fueling brain function. However, if little carbohydrate remains in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.[1] Around half of children and young people with epilepsy who have tried some form of this diet saw the number of seizures drop by at least half, and the effect persists even after discontinuing the diet.[2] Some evidence indicates that adults with epilepsy may benefit from the diet, and that a less strict regimen, such as a modified Atkins diet, is similarly effective.[1] Side effects include constipation, high cholesterol, growth slowing, acidosis, and kidney stones.[3]
The original therapeutic diet for paediatric epilepsy provides just enough protein for body growth and repair, and sufficient calories[Note 1] to maintain the correct weight for age and height. The classic therapeutic ketogenic diet was developed for treatment of paediatric epilepsy in the 1920s and was widely used into the next decade, but its popularity waned with the introduction of effective anticonvulsant medications. This classic ketogenic diet contains a 4:1 ratio by weight of fat to combined protein and carbohydrate. This is achieved by excluding high-carbohydrate foods such as starchy fruits and vegetables, bread, pasta, grains, and sugar, while increasing the consumption of foods high in fat such as nuts, cream, and butter.[1] Most dietary fat is made of molecules called long-chain triglycerides (LCTs). However, medium-chain triglycerides (MCTs)—made from fatty acids with shorter carbon chains than LCTs—are more ketogenic. A variant of the classic diet known as the MCT ketogenic diet uses a form of coconut oil, which is rich in MCTs, to provide around half the calories. As less overall fat is needed in this variant of the diet, a greater proportion of carbohydrate and protein can be consumed, allowing a greater variety of food choices.[4][5]
In the mid-1990s, Hollywood producer Jim Abrahams, whose son's severe epilepsy was effectively controlled by the diet, created the Charlie Foundation to promote it. Publicity included an appearance on NBC's Dateline programme and ...First Do No Harm (1997), a made-for-television film starring Meryl Streep. The foundation sponsored a multicentre research study, the results of which—announced in 1996—marked the beginning of renewed scientific interest in the diet.[1]
Possible therapeutic uses for the ketogenic diet have been studied for various neurological disorders in addition to epilepsy: Alzheimer's disease, amyotrophic lateral sclerosis, autism, brain cancer, headache, neurotrauma, pain, Parkinson's disease, and sleep disorders.[6]
Epilepsy
Epilepsy is one of the most common neurological disorders after stroke,[7] and affects around 50 million people worldwide.[8] It is diagnosed in a person having recurrent, unprovoked seizures. These occur when cortical neurons fire excessively, hypersynchronously, or both, leading to temporary disruption of normal brain function. This might affect, for example, the muscles, the senses, consciousness, or a combination. A seizure can be focal (confined to one part of the brain) or generalised (spread widely throughout the brain and leading to a loss of consciousness). Epilepsy can occur for a variety of reasons; some forms have been classified into epileptic syndromes, most of which begin in childhood. Epilepsy is considered refractory (not yielding to treatment) when two or three anticonvulsant drugs have failed to control it. About 60% of patients achieve control of their epilepsy with the first drug they use, whereas around 30% do not achieve control with drugs. When drugs fail, other options include epilepsy surgery, vagus nerve stimulation, and the ketogenic diet.[7]
History
The ketogenic diet is a mainstream dietary therapy that was developed to reproduce the success and remove the limitations of the non-mainstream use of fasting to treat epilepsy.[Note 2] Although popular in the 1920s and '30s, it was largely abandoned in favour of new anticonvulsant drugs.[1] Most individuals with epilepsy can successfully control their seizures with medication. However, 20–30% fail to achieve such control despite trying a number of different drugs.[9] For this group, and for children in particular, the diet has once again found a role in epilepsy management.[1][10]
Fasting
A news report of Dr Hugh Conklin's "water diet" treatment from 1922
Physicians of ancient Greece treated diseases, including epilepsy, by altering their patients' diet. An early treatise in the Hippocratic Corpus, On the Sacred Disease, covers the disease; it dates from c. 400 BC. Its author argued against the prevailing view that epilepsy was supernatural in origin and cure, and proposed that dietary therapy had a rational and physical basis.[Note 3] In the same collection, the author of Epidemics describes the case of a man whose epilepsy is cured as quickly as it had appeared, through complete abstinence of food and drink.[Note 4] The royal physician Erasistratus declared, "One inclining to epilepsy should be made to fast without mercy and be put on short rations."[Note 5] Galen believed an "attenuating diet"[Note 6] might afford a cure in mild cases and be helpful in others.[11]
The first modern study of fasting as a treatment for epilepsy was in France in 1911.[12] Twenty epilepsy patients of all ages were "detoxified" by consuming a low-calorie vegetarian diet, combined with periods of fasting and purging. Two benefited enormously, but most failed to maintain compliance with the imposed restrictions. The diet improved the patients' mental capabilities, in contrast to their medication, potassium bromide, which dulled the mind.[13]
Around this time, Bernarr Macfadden, an American exponent of physical culture, popularised the use of fasting to restore health. His disciple, the osteopathic physician Dr. Hugh William Conklin of Battle Creek, Michigan, began to treat his epilepsy patients by recommending fasting. Conklin conjectured that epileptic seizures were caused when a toxin, secreted from the Peyer's patches in the intestines, was discharged into the bloodstream. He recommended a fast lasting 18 to 25 days to allow this toxin to dissipate. Conklin probably treated hundreds of epilepsy patients with his "water diet" and boasted of a 90% cure rate in children, falling to 50% in adults. Later analysis of Conklin's case records showed 20% of his patients achieved freedom from seizures and 50% had some improvement.[10]
Conklin's fasting therapy was adopted by neurologists in mainstream practice. In 1916, a Dr McMurray wrote to the New York Medical Journal claiming to have successfully treated epilepsy patients with a fast, followed by a starch- and sugar-free diet, since 1912. In 1921, prominent endocrinologist Henry Rawle Geyelin reported his experiences to the American Medical Association convention. He had seen Conklin's success first-hand and had attempted to reproduce the results in 36 of his own patients. He achieved similar results despite only having studied the patients for a short time. Further studies in the 1920s indicated that seizures generally returned after the fast. Charles P. Howland, the parent of one of Conklin's successful patients and a wealthy New York corporate lawyer, gave his brother John Elias Howland a gift of $5,000 to study "the ketosis of starvation". As professor of paediatrics at Johns Hopkins Hospital, John E. Howland used the money to fund research undertaken by neurologist Stanley Cobb and his assistant William G. Lennox.[10]
Diet
In 1921, Rollin Turner Woodyatt reviewed the research on diet and diabetes. He reported that three water-soluble compounds, β-hydroxybutyrate, acetoacetate, and acetone (known collectively as ketone bodies), were produced by the liver in otherwise healthy people when they were starved or if they consumed a very low-carbohydrate, high-fat diet.[10] Dr. Russell Morse Wilder, at the Mayo Clinic, built on this research and coined the term "ketogenic diet" to describe a diet that produced a high level of ketone bodies in the blood (ketonemia) through an excess of fat and lack of carbohydrate. Wilder hoped to obtain the benefits of fasting in a dietary therapy that could be maintained indefinitely. His trial on a few epilepsy patients in 1921 was the first use of the ketogenic diet as a treatment for epilepsy.[10]
Wilder's colleague, paediatrician Mynie Gustav Peterman, later formulated the classic diet, with a ratio of one gram of protein per kilogram of body weight in children, 10–15 g of carbohydrate per day, and the remainder of calories from fat. Peterman's work in the 1920s established the techniques for induction and maintenance of the diet. Peterman documented positive effects (improved alertness, behaviour, and sleep) and adverse effects (nausea and vomiting due to excess ketosis). The diet proved to be very successful in children: Peterman reported in 1925 that 95% of 37 young patients had improved seizure control on the diet and 60% became seizure-free. By 1930, the diet had also been studied in 100 teenagers and adults. Clifford Joseph Barborka, Sr., also from the Mayo Clinic, reported that 56% of those older patients improved on the diet and 12% became seizure-free. Although the adult results are similar to modern studies of children, they did not compare as well to contemporary studies. Barborka concluded that adults were least likely to benefit from the diet, and the use of the ketogenic diet in adults was not studied again until 1999.[10][14]
Anticonvulsants and decline
During the 1920s and 1930s, when the only anticonvulsant drugs were the sedative bromides (discovered 1857) and phenobarbital (1912), the ketogenic diet was widely used and studied. This changed in 1938 when H. Houston Merritt, Jr. and Tracy Putnam discovered phenytoin (Dilantin), and the focus of research shifted to discovering new drugs. With the introduction of sodium valproate in the 1970s, drugs were available to neurologists that were effective across a broad range of epileptic syndromes and seizure types. The use of the ketogenic diet, by this time restricted to difficult cases such as Lennox–Gastaut syndrome, declined further.[10]
MCT diet
Medium-chain triglyceride (MCT) oil emulsion
In the 1960s, medium-chain triglycerides (MCTs) were found to produce more ketone bodies per unit of energy than normal dietary fats (which are mostly long-chain triglycerides).[15] MCTs are more efficiently absorbed and are rapidly transported to the liver via the hepatic portal system rather than the lymphatic system.[16] The severe carbohydrate restrictions of the classic ketogenic diet made it difficult for parents to produce palatable meals that their children would tolerate. In 1971, Peter Huttenlocher devised a ketogenic diet where about 60% of the calories came from the MCT oil, and this allowed more protein and up to three times as much carbohydrate as the classic ketogenic diet. The oil was mixed with at least twice its volume of skimmed milk, chilled, and sipped during the meal or incorporated into food. He tested it on 12 children and adolescents with intractable seizures. Most children improved in both seizure control and alertness, results that were similar to the classic ketogenic diet. Gastrointestinal upset was a problem, which led one patient to abandon the diet, but meals were easier to prepare and better accepted by the children.[15] The MCT diet replaced the classic ketogenic diet in many hospitals, though some devised diets that were a combination of the two.[10]
Revival
The ketogenic diet achieved national media exposure in the US in October 1994, when NBC's Dateline television programme reported the case of Charlie Abrahams, son of Hollywood producer Jim Abrahams. The two-year-old suffered from epilepsy that had remained uncontrolled by mainstream and alternative therapies. Abrahams discovered a reference to the ketogenic diet in an epilepsy guide for parents and brought Charlie to John M. Freeman at Johns Hopkins Hospital, which had continued to offer the therapy. Under the diet, Charlie's epilepsy was rapidly controlled and his developmental progress resumed. This inspired Abrahams to create the Charlie Foundation to promote the diet and fund research.[10] A multicentre prospective study began in 1994, the results were presented to the American Epilepsy Society in 1996 and were published[17] in 1998. There followed an explosion of scientific interest in the diet. In 1997, Abrahams produced a TV movie, ...First Do No Harm, starring Meryl Streep, in which a young boy's intractable epilepsy is successfully treated by the ketogenic diet.[1]
By 2007, the ketogenic diet was available from around 75 centres in 45 countries, and less restrictive variants, such as the modified Atkins diet, were in use, particularly among older children and adults. The ketogenic diet was also under investigation for the treatment of a wide variety of disorders other than epilepsy.[1]
Efficacy
The ketogenic diet reduces seizure frequency by more than 50% in half of the patients who try it and by more than 90% in a third of patients.[18] Three-quarters of children who respond do so within two weeks, though experts recommend a trial of at least three months before assuming it has been ineffective.[9] Children with refractory epilepsy are more likely to benefit from the ketogenic diet than from trying another anticonvulsant drug.[1] Some evidence indicates that adolescents and adults may also benefit from the diet.[9]
Trial design
Early studies reported high success rates; in one study in 1925, 60% of patients became seizure-free, and another 35% of patients had a 50% reduction in seizure frequency. These studies generally examined a cohort of patients recently treated by the physician (a retrospective study) and selected patients who had successfully maintained the dietary restrictions. However, these studies are difficult to compare to modern trials. One reason is that these older trials suffered from selection bias, as they excluded patients who were unable to start or maintain the diet and thereby selected from patients who would generate better results. In an attempt to control for this bias, modern study design prefers a prospective cohort (the patients in the study are chosen before therapy begins) in which the results are presented for all patients regardless of whether they started or completed the treatment (known as intent-to-treat analysis).[19]
Another difference between older and newer studies is that the type of patients treated with the ketogenic diet has changed over time. When first developed and used, the ketogenic diet was not a treatment of last resort; in contrast, the children in modern studies have already tried and failed a number of anticonvulsant drugs, so may be assumed to have more difficult-to-treat epilepsy. Early and modern studies also differ because the treatment protocol has changed. In older protocols, the diet was initiated with a prolonged fast, designed to lose 5–10% body weight, and heavily restricted the calorie intake. Concerns over child health and growth led to a relaxation of the diet's restrictions.[19] Fluid restriction was once a feature of the diet, but this led to increased risk of constipation and kidney stones, and is no longer considered beneficial.[18]
Outcomes
A study with an intent-to-treat prospective design was published in 1998 by a team from the Johns Hopkins Hospital[20] and followed-up by a report published in 2001.[21] As with most studies of the ketogenic diet, no control group (patients who did not receive the treatment) was used. The study enrolled 150 children. After three months, 83% of them were still on the diet, 26% had experienced a good reduction in seizures, 31% had had an excellent reduction, and 3% were seizure-free.[Note 7] At 12 months, 55% were still on the diet, 23% had a good response, 20% had an excellent response, and 7% were seizure-free. Those who had discontinued the diet by this stage did so because it was ineffective, too restrictive, or due to illness, and most of those who remained were benefiting from it. The percentage of those still on the diet at two, three, and four years was 39%, 20%, and 12%, respectively. During this period, the most common reason for discontinuing the diet was because the children had become seizure-free or significantly better. At four years, 16% of the original 150 children had a good reduction in seizure frequency, 14% had an excellent reduction, and 13% were seizure-free, though these figures include many who were no longer on the diet. Those remaining on the diet after this duration were typically not seizure-free, but had had an excellent response.[21][22]
It is possible to combine the results of several small studies to produce evidence that is stronger than that available from each study alone—a statistical method known as meta-analysis. One of four such analyses, conducted in 2006, looked at 19 studies on a total of 1,084 patients.[23] It concluded that a third achieved an excellent reduction in seizure frequency and half the patients achieved a good reduction.[18]
A Cochrane systematic review in 2018 found and analysed eleven randomized controlled trials of ketogenic diet in people with epilepsy for whom drugs failed to control their seizures.[2] Six of the trials compared a group assigned to a ketogenic diet with a group not assigned to one. The other trials compared types of diets or ways of introducing them to make them more tolerable.[2] In the largest trial of the ketogenic diet with a non-diet control[16], nearly 38% of the children and young people had half or fewer seizures with the diet compared 6% with the group not assigned to the diet. Two large trials of the Modified Atkins Diet compared to a non-diet control had similar results, with over 50% of children having half or fewer seizures with the diet compared to around 10% in the control group.[2]
A systematic review in 2018 looked at 16 studies on the ketogenic diet in adults. It concluded that the treatment was becoming more popular for that group of patients, that the efficacy in adults was similar to children, the side effects relatively mild. However, many patients gave up with the diet, for various reasons, and the quality of evidence inferior to studies on children. Health issues include high levels of low-density lipoprotein, high total cholesterol, and weight loss.[24]
Indications and contra-indications
The ketogenic diet is indicated as an adjunctive (additional) treatment in children and young people with drug-resistant epilepsy.[26][27] It is approved by national clinical guidelines in Scotland,[27] England, and Wales[26] and reimbursed by nearly all US insurance companies.[28] Children with a focal lesion (a single point of brain abnormality causing the epilepsy) who would make suitable candidates for surgery are more likely to become seizure-free with surgery than with the ketogenic diet.[9][29] About a third of epilepsy centres that offer the ketogenic diet also offer a dietary therapy to adults. Some clinicians consider the two less restrictive dietary variants—the low glycaemic index treatment and the modified Atkins diet—to be more appropriate for adolescents and adults.[9] A liquid form of the ketogenic diet is particularly easy to prepare for, and well tolerated by, infants on formula and children who are tube-fed.[5][30]
Advocates for the diet recommend that it be seriously considered after two medications have failed, as the chance of other drugs succeeding is only 10%.[9][31][32] The diet can be considered earlier for some epilepsy and genetic syndromes where it has shown particular usefulness. These include Dravet syndrome, infantile spasms, myoclonic-astatic epilepsy, and tuberous sclerosis complex.[9][33]
A survey in 2005 of 88 paediatric neurologists in the US found that 36% regularly prescribed the diet after three or more drugs had failed, 24% occasionally prescribed the diet as a last resort, 24% had only prescribed the diet in a few rare cases, and 16% had never prescribed the diet. Several possible explanations exist for this gap between evidence and clinical practice.[34] One major factor may be the lack of adequately trained dietitians, who are needed to administer a ketogenic diet programme.[31]
Because the ketogenic diet alters the body's metabolism, it is a first-line therapy in children with certain congenital metabolic diseases such as pyruvate dehydrogenase (E1) deficiency and glucose transporter 1 deficiency syndrome,[35] which prevent the body from using carbohydrates as fuel, leading to a dependency on ketone bodies. The ketogenic diet is beneficial in treating the seizures and some other symptoms in these diseases and is an absolute indication.[36] However, it is absolutely contraindicated in the treatment of other diseases such as pyruvate carboxylase deficiency, porphyria, and other rare genetic disorders of fat metabolism.[9] Persons with a disorder of fatty acid oxidation are unable to metabolise fatty acids, which replace carbohydrates as the major energy source on the diet. On the ketogenic diet, their bodies would consume their own protein stores for fuel, leading to ketoacidosis, and eventually coma and death.[37]
Interactions
The ketogenic diet is usually initiated in combination with the patient's existing anticonvulsant regimen, though patients may be weaned off anticonvulsants if the diet is successful. Some evidence of synergistic benefits is seen when the diet is combined with the vagus nerve stimulator or with the drug zonisamide, and that the diet may be less successful in children receiving phenobarbital.[18]
Adverse effects
The ketogenic diet is not a benign, holistic, or natural treatment for epilepsy; as with any serious medical therapy, complications may result.[28] These are generally less severe and less frequent than with anticonvulsant medication or surgery.[28] Common but easily treatable short-term side effects include constipation, low-grade acidosis, and hypoglycaemia if an initial fast is undertaken. Raised levels of lipids in the blood affect up to 60% of children[38] and cholesterol levels may increase by around 30%.[28] This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and if persistent, by lowering the ketogenic ratio.[38] Supplements are necessary to counter the dietary deficiency of many micronutrients.[18]
Long-term use of the ketogenic diet in children increases the risk of slowed or stunted growth, bone fractures, and kidney stones.[18] The diet reduces levels of insulin-like growth factor 1, which is important for childhood growth. Like many anticonvulsant drugs, the ketogenic diet has an adverse effect on bone health. Many factors may be involved such as acidosis and suppressed growth hormone.[38] About one in 20 children on the ketogenic diet develop kidney stones (compared with one in several thousand for the general population). A class of anticonvulsants known as carbonic anhydrase inhibitors (topiramate, zonisamide) are known to increase the risk of kidney stones, but the combination of these anticonvulsants and the ketogenic diet does not appear to elevate the risk above that of the diet alone.[39] The stones are treatable and do not justify discontinuation of the diet.[39] Johns Hopkins Hospital now gives oral potassium citrate supplements to all ketogenic diet patients, resulting in one-seventh of the incidence of kidney stones.[40] However, this empiric usage has not been tested in a prospective controlled trial.[9] Kidney stone formation (nephrolithiasis) is associated with the diet for four reasons:[39]
Excess calcium in the urine (hypercalciuria) occurs due to increased bone demineralisation with acidosis. Bones are mainly composed of calcium phosphate. The phosphate reacts with the acid, and the calcium is excreted by the kidneys.[39]
Hypocitraturia: the urine has an abnormally low concentration of citrate, which normally helps to dissolve free calcium.[39]
The urine has a low pH, which stops uric acid from dissolving, leading to crystals that act as a nidus for calcium stone formation.[39]
Many institutions traditionally restricted the water intake of patients on the diet to 80% of normal daily needs;[39] this practice is no longer encouraged.[18]
In adolescent and adults, common side effects reported include weight loss, constipation, dyslipidemia, and in women, dysmenorrhea.[41]
Implementation
The ketogenic diet is a medical nutrition therapy that involves participants from various disciplines. Team members include a registered paediatric dietitian who coordinates the diet programme; a paediatric neurologist who is experienced in offering the ketogenic diet; and a registered nurse who is familiar with childhood epilepsy. Additional help may come from a medical social worker who works with the family and a pharmacist who can advise on the carbohydrate content of medicines. Lastly, the parents and other caregivers must be educated in many aspects of the diet for it to be safely implemented.[5]
Implementing the diet can present difficulties for caregivers and the patient due to the time commitment involved in measuring and planning meals. Since any unplanned eating can potentially break the nutritional balance required, some people find the discipline needed to maintain the diet challenging and unpleasant. Some people terminate the diet or switch to a less demanding diet, like the modified Atkins diet or the low-glycaemic index treatment diet, because they find the difficulties too great.[42]
Initiation
The Johns Hopkins Hospital protocol for initiating the ketogenic diet has been widely adopted.[43] It involves a consultation with the patient and their caregivers and, later, a short hospital admission.[19] Because of the risk of complications during ketogenic diet initiation, most centres begin the diet under close medical supervision in the hospital.[9]
At the initial consultation, patients are screened for conditions that may contraindicate the diet. A dietary history is obtained and the parameters of the diet selected: the ketogenic ratio of fat to combined protein and carbohydrate, the calorie requirements and the fluid intake.[19]
The day before admission to hospital, the proportion of carbohydrate in the diet may be decreased and the patient begins fasting after his or her evening meal.[19] On admission, only calorie- and caffeine-free fluids[37] are allowed until dinner, which consists of "eggnog"[Note 8] restricted to one-third of the typical calories for a meal. The following breakfast and lunch are similar, and on the second day, the "eggnog" dinner is increased to two-thirds of a typical meal's caloric content. By the third day, dinner contains the full calorie quota and is a standard ketogenic meal (not "eggnog"). After a ketogenic breakfast on the fourth day, the patient is discharged. Where possible, the patient's current medicines are changed to carbohydrate-free formulations.[19]
When in the hospital, glucose levels are checked several times daily and the patient is monitored for signs of symptomatic ketosis (which can be treated with a small quantity of orange juice). Lack of energy and lethargy are common, but disappear within two weeks.[17] The parents attend classes over the first three full days, which cover nutrition, managing the diet, preparing meals, avoiding sugar, and handling illness.[19] The level of parental education and commitment required is higher than with medication.[44]
Variations on the Johns Hopkins protocol are common. The initiation can be performed using outpatient clinics rather than requiring a stay in hospital. Often, no initial fast is used (fasting increases the risk of acidosis, hypoglycaemia, and weight loss). Rather than increasing meal sizes over the three-day initiation, some institutions maintain meal size, but alter the ketogenic ratio from 2:1 to 4:1.[9]
For patients who benefit, half achieve a seizure reduction within five days (if the diet starts with an initial fast of one to two days), three-quarters achieve a reduction within two weeks, and 90% achieve a reduction within 23 days. If the diet does not begin with a fast, the time for half of the patients to achieve an improvement is longer (two weeks), but the long-term seizure reduction rates are unaffected.[44] Parents are encouraged to persist with the diet for at least three months before any final consideration is made regarding efficacy.[9]
Maintenance
After initiation, the child regularly visits the hospital outpatient clinic where he or she is seen by the dietitian and neurologist, and various tests and examinations are performed. These are held every three months for the first year and then every six months thereafter. Infants under one year old are seen more frequently, with the initial visit held after just two to four weeks.[9] A period of minor adjustments is necessary to ensure consistent ketosis is maintained and to better adapt the meal plans to the patient. This fine-tuning is typically done over the telephone with the hospital dietitian[19] and includes changing the number of calories, altering the ketogenic ratio, or adding some MCT or coconut oils to a classic diet.[18] Urinary ketone levels are checked daily to detect whether ketosis has been achieved and to confirm that the patient is following the diet, though the level of ketones does not correlate with an anticonvulsant effect.[19] This is performed using ketone test strips containing nitroprusside, which change colour from buff-pink to maroon in the presence of acetoacetate (one of the three ketone bodies).[45]
A short-lived increase in seizure frequency may occur during illness or if ketone levels fluctuate. The diet may be modified if seizure frequency remains high, or the child is losing weight.[19] Loss of seizure-control may come from unexpected sources. Even "sugar-free" food can contain carbohydrates such as maltodextrin, sorbitol, starch, and fructose. The sorbitol content of suntan lotion and other skincare products may be high enough for some to be absorbed through the skin and thus negate ketosis.[31]
Discontinuation
About 20% of children on the ketogenic diet achieve freedom from seizures, and many are able to reduce the use of anticonvulsant drugs or eliminate them altogether.[18] Commonly, at around two years on the diet, or after six months of being seizure-free, the diet may be gradually discontinued over two or three months. This is done by lowering the ketogenic ratio until urinary ketosis is no longer detected, and then lifting all calorie restrictions.[46] This timing and method of discontinuation mimics that of anticonvulsant drug therapy in children, where the child has become seizure-free. When the diet is required to treat certain metabolic diseases, the duration will be longer. The total diet duration is up to the treating ketogenic diet team and parents; durations up to 12 years have been studied and found beneficial.[9]
Children who discontinue the diet after achieving seizure freedom have about a 20% risk of seizures returning. The length of time until recurrence is highly variable, but averages two years. This risk of recurrence compares with 10% for resective surgery (where part of the brain is removed) and 30–50% for anticonvulsant therapy. Of those who have a recurrence, just over half can regain freedom from seizures either with anticonvulsants or by returning to the ketogenic diet. Recurrence is more likely if, despite seizure freedom, an electroencephalogram shows epileptiform spikes, which indicate epileptic activity in the brain but are below the level that will cause a seizure. Recurrence is also likely if an MRI scan shows focal abnormalities (for example, as in children with tuberous sclerosis). Such children may remain on the diet longer than average, and children with tuberous sclerosis who achieve seizure freedom could remain on the ketogenic diet indefinitely.[46]
Variants
Classic
The ratio of calorific contributions from food components of four diets, by weight
The ketogenic diet is calculated by a dietitian for each child. Age, weight, activity levels, culture, and food preferences all affect the meal plan. First, the energy requirements are set at 80–90% of the recommended daily amounts (RDA) for the child's age (the high-fat diet requires less energy to process than a typical high-carbohydrate diet). Highly active children or those with muscle spasticity require more food energy than this; immobile children require less. The ketogenic ratio of the diet compares the weight of fat to the combined weight of carbohydrate and protein. This is typically 4:1, but children who are younger than 18 months, older than 12 years, or who are obese may be started on a 3:1 ratio. Fat is energy-rich, with 9 kcal/g (38 kJ/g) compared to 4 kcal/g (17 kJ/g) for carbohydrate or protein, so portions on the ketogenic diet are smaller than normal. The quantity of fat in the diet can be calculated from the overall energy requirements and the chosen ketogenic ratio. Next, the protein levels are set to allow for growth and body maintenance, and are around 1 g protein for each kg of body weight. Lastly, the amount of carbohydrate is set according to what allowance is left while maintaining the chosen ratio. Any carbohydrate in medications or supplements must be subtracted from this allowance. The total daily amount of fat, protein, and carbohydrate is then evenly divided across the meals.[37]
A computer program such as KetoCalculator may be used to help generate recipes.[47] The meals often have four components: heavy whipping cream, a protein-rich food (typically meat), a fruit or vegetable and a fat such as butter, vegetable oil, or mayonnaise. Only low-carbohydrate fruits and vegetables are allowed, which excludes bananas, potatoes, peas, and corn. Suitable fruits are divided into two groups based on the amount of carbohydrate they contain, and vegetables are similarly divided into two groups. Foods within each of these four groups may be freely substituted to allow for variation without needing to recalculate portion sizes. For example, cooked broccoli, Brussels sprouts, cauliflower, and green beans are all equivalent. Fresh, canned, or frozen foods are equivalent, but raw and cooked vegetables differ, and processed foods are an additional complication. Parents are required to be precise when measuring food quantities on an electronic scale accurate to 1 g. The child must eat the whole meal and cannot have extra portions; any snacks must be incorporated into the meal plan. A small amount of MCT oil may be used to help with constipation or to increase ketosis.[37]
The classic ketogenic diet is not a balanced diet and only contains tiny portions of fresh fruit and vegetables, fortified cereals, and calcium-rich foods. In particular, the B vitamins, calcium, and vitamin D must be artificially supplemented. This is achieved by taking two sugar-free supplements designed for the patient's age: a multivitamin with minerals and calcium with vitamin D.[18] A typical day of food for a child on a 4:1 ratio, 1,500 kcal (6,300 kJ) ketogenic diet comprises:[28]
Breakfast: egg with bacon
28 g egg, 11 g bacon, 37 g of 36% heavy whipping cream, 23 g butter, and a 9-g apple
Snack: peanut butter ball
6 g peanut butter and 9 g butter
Lunch: tuna salad
28 g tuna fish, 30 g mayonnaise, 10 g celery, 36 g of 36% heavy whipping cream, and 15 g lettuce
Snack: keto yogurt
18 g of 36% heavy whipping cream, 17 g sour cream, 4 g strawberries, and artificial sweetener
Dinner: cheeseburger (no bun)
22 g minced (ground) beef, 10 g American cheese, 26 g butter, 38 g cream, 10 g lettuce, and 11 g green beans
Snack: keto custard
25 g of 36% heavy whipping cream, 9 g egg, and pure vanilla flavouring
MCT oil
Normal dietary fat contains mostly long-chain triglycerides (LCTs). Medium-chain triglycerides (MCTs) are more ketogenic than LCTs because they generate more ketones per unit of energy when metabolised. Their use allows for a diet with a lower proportion of fat and a greater proportion of protein and carbohydrate,[18] leading to more food choices and larger portion sizes.[4] The original MCT diet developed by Peter Huttenlocher in the 1970s derived 60% of its calories from MCT oil.[15] Consuming that quantity of MCT oil caused abdominal cramps, diarrhea, and vomiting in some children. A figure of 45% is regarded as a balance between achieving good ketosis and minimising gastrointestinal complaints. The classical and modified MCT ketogenic diets are equally effective and differences in tolerability are not statistically significant.[9] The MCT diet is less popular in the United States; MCT oil is more expensive than other dietary fats and is not covered by insurance companies.[18]
Modified Atkins
First reported in 2003, the idea of using a form of the Atkins diet to treat epilepsy came about after parents and patients discovered that the induction phase of the Atkins diet controlled seizures. The ketogenic diet team at Johns Hopkins Hospital modified the Atkins diet by removing the aim of achieving weight loss, extending the induction phase indefinitely, and specifically encouraging fat consumption. Compared with the ketogenic diet, the modified Atkins diet (MAD) places no limit on calories or protein, and the lower overall ketogenic ratio (about 1:1) does not need to be consistently maintained by all meals of the day. The MAD does not begin with a fast or with a stay in hospital and requires less dietitian support than the ketogenic diet. Carbohydrates are initially limited to 10 g per day in children or 20 g per day in adults, and are increased to 20–30 g per day after a month or so, depending on the effect on seizure control or tolerance of the restrictions. Like the ketogenic diet, the MAD requires vitamin and mineral supplements and children are carefully and periodically monitored at outpatient clinics.[48]
The modified Atkins diet reduces seizure frequency by more than 50% in 43% of patients who try it and by more than 90% in 27% of patients.[18] Few adverse effects have been reported, though cholesterol is increased and the diet has not been studied long term.[48] Although based on a smaller data set (126 adults and children from 11 studies over five centres), these results from 2009 compare favourably with the traditional ketogenic diet.[18]
Low glycaemic index treatment
The low glycaemic index treatment (LGIT)[49] is an attempt to achieve the stable blood glucose levels seen in children on the classic ketogenic diet while using a much less restrictive regimen. The hypothesis is that stable blood glucose may be one of the mechanisms of action involved in the ketogenic diet,[9] which occurs because the absorption of the limited carbohydrates is slowed by the high fat content.[5] Although it is also a high-fat diet (with approximately 60% calories from fat),[5] the LGIT allows more carbohydrate than either the classic ketogenic diet or the modified Atkins diet, approximately 40–60 g per day.[18] However, the types of carbohydrates consumed are restricted to those that have a glycaemic index lower than 50. Like the modified Atkins diet, the LGIT is initiated and maintained at outpatient clinics and does not require precise weighing of food or intensive dietitian support. Both are offered at most centres that run ketogenic diet programmes, and in some centres they are often the primary dietary therapy for adolescents.[9]
Short-term results for the LGIT indicate that at one month approximately half of the patients experience a greater than 50% reduction in seizure frequency, with overall figures approaching that of the ketogenic diet. The data (coming from one centre's experience with 76 children up to the year 2009) also indicate fewer side effects than the ketogenic diet and that it is better tolerated, with more palatable meals.[18][50]
Prescribed formulations
Measuring KetoCal—a powdered formula for administering the classic ketogenic diet
Infants and patients fed via a gastrostomy tube can also be given a ketogenic diet. Parents make up a prescribed powdered formula, such as KetoCal, into a liquid feed.[19] Gastrostomy feeding avoids any issues with palatability, and bottle-fed infants readily accept the ketogenic formula.[31] Some studies have found this liquid feed to be more efficacious and associated with lower total cholesterol than a solid ketogenic diet.[18] KetoCal is a nutritionally complete food containing milk protein and is supplemented with amino acids, fat, carbohydrate, vitamins, minerals and trace elements. It is used to administer the 4:1 ratio classic ketogenic diet in children over one year. The formula is available in both 3:1 and 4:1 ratios, either unflavoured or in an artificially sweetened vanilla flavour and is suitable for tube or oral feeding.[51] Other formula products include KetoVolve[52] and Ketonia.[53] Alternatively, a liquid ketogenic diet may be produced by combining Ross Carbohydrate Free soy formula with Microlipid and Polycose.[53]
Worldwide
There are theoretically no restrictions on where the ketogenic diet might be used, and it can cost less than modern anticonvulsants. However, fasting and dietary changes are affected by religious and cultural issues. A culture where food is often prepared by grandparents or hired help means more people must be educated about the diet. When families dine together, sharing the same meal, it can be difficult to separate the child's meal. In many countries, food labelling is not mandatory so calculating the proportions of fat, protein and carbohydrate is difficult. In some countries, it may be hard to find sugar-free forms of medicines and supplements, to purchase an accurate electronic scale, or to afford MCT oils.[54]
In Asia, the normal diet includes rice and noodles as the main energy source, making their elimination difficult. Therefore, the MCT-oil form of the diet, which allows more carbohydrate, has proved useful. In India, religious beliefs commonly affect the diet: some patients are vegetarians, will not eat root vegetables or avoid beef. The Indian ketogenic diet is started without a fast due to cultural opposition towards fasting in children. The low-fat, high-carbohydrate nature of the normal Indian and Asian diet means that their ketogenic diets typically have a lower ketogenic ratio (1:1) than in America and Europe. However, they appear to be just as effective.[54]
In many developing countries, the ketogenic diet is expensive because dairy fats and meat are more expensive than grain, fruit and vegetables. The modified Atkins diet has been proposed as a lower-cost alternative for those countries; the slightly more expensive food bill can be offset by a reduction in pharmaceutical costs if the diet is successful. The modified Atkins diet is less complex to explain and prepare and requires less support from a dietitian.[55]
Mechanism of action
Seizure pathology
The brain is composed of a network of neurons that transmit signals by propagating nerve impulses. The propagation of this impulse from one neuron to another is typically controlled by neurotransmitters, though there are also electrical pathways between some neurons. Neurotransmitters can inhibit impulse firing (primarily done by γ-aminobutyric acid, or GABA) or they can excite the neuron into firing (primarily done by glutamate). A neuron that releases inhibitory neurotransmitters from its terminals is called an inhibitory neuron, while one that releases excitatory neurotransmitters is an excitatory neuron. When the normal balance between inhibition and excitation is significantly disrupted in all or part of the brain, a seizure can occur. The GABA system is an important target for anticonvulsant drugs, since seizures may be discouraged by increasing GABA synthesis, decreasing its breakdown, or enhancing its effect on neurons.[7]
The nerve impulse is characterised by a great influx of sodium ions through channels in the neuron's cell membrane followed by an efflux of potassium ions through other channels. The neuron is unable to fire again for a short time (known as the refractory period), which is mediated by another potassium channel. The flow through these ion channels is governed by a "gate" which is opened by either a voltage change or a chemical messenger known as a ligand (such as a neurotransmitter). These channels are another target for anticonvulsant drugs.[7]
There are many ways in which epilepsy occurs. Examples of pathological physiology include: unusual excitatory connections within the neuronal network of the brain; abnormal neuron structure leading to altered current flow; decreased inhibitory neurotransmitter synthesis; ineffective receptors for inhibitory neurotransmitters; insufficient breakdown of excitatory neurotransmitters leading to excess; immature synapse development; and impaired function of ionic channels.[7]
Seizure control
Although many hypotheses have been put forward to explain how the ketogenic diet works, it remains a mystery. Disproven hypotheses include systemic acidosis (high levels of acid in the blood), electrolyte changes and hypoglycaemia (low blood glucose).[19] Although many biochemical changes are known to occur in the brain of a patient on the ketogenic diet, it is not known which of these has an anticonvulsant effect. The lack of understanding in this area is similar to the situation with many anticonvulsant drugs.[56]
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[57] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[56]
The ketone bodies are possibly anticonvulsant; in animal models, acetoacetate and acetone protect against seizures. The ketogenic diet results in adaptive changes to brain energy metabolism that increase the energy reserves; ketone bodies are a more efficient fuel than glucose, and the number of mitochondria is increased. This may help the neurons to remain stable in the face of increased energy demand during a seizure, and may confer a neuroprotective effect.[56]
The ketogenic diet has been studied in at least 14 rodent animal models of seizures. It is protective in many of these models and has a different protection profile than any known anticonvulsant. Conversely, fenofibrate, not used clinically as an antiepileptic, exhibits experimental anticonvulsant properties in adult rats comparable to the ketogenic diet.[58] This, together with studies showing its efficacy in patients who have failed to achieve seizure control on half a dozen drugs, suggests a unique mechanism of action.[56]
Anticonvulsants suppress epileptic seizures, but they neither cure nor prevent the development of seizure susceptibility. The development of epilepsy (epileptogenesis) is a process that is poorly understood. A few anticonvulsants (valproate, levetiracetam and benzodiazepines) have shown antiepileptogenic properties in animal models of epileptogenesis. However, no anticonvulsant has ever achieved this in a clinical trial in humans. The ketogenic diet has been found to have antiepileptogenic properties in rats.[56]
Other applications
The ketogenic diet has been studied for potential therapeutic use in various neurological disorders other than epilepsy: Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), autism, headache, neurotrauma, pain, Parkinson's disease (PD) and sleep disorders.[6]
Because some cancer cells are inefficient in processing ketone bodies for energy, the ketogenic diet has also been suggested as a treatment for cancer.[59][60] A 2018 review looked at the evidence from preclinical and clinical studies of ketogenic diets in cancer therapy. The clinical studies in humans are typically very small, with some providing weak evidence for anti-tumour effect, particularly for glioblastoma, but in other cancers and studies, no anti-tumour effect was seen. Taken together, results from preclinical studies, albeit sometimes contradictory, tend to support an anti-tumor effect rather than a pro-tumor effect of the KD for most solid cancers.[61]
The evidence of benefit for these conditions has not reached the level where clinical recommendations can be made.[9]
Kosher foods
Kosher meal approved by the Beth din of Johannesburg
Kosher foods are those that conform to the Jewish dietary regulations of kashrut (dietary law), primarily derived from Leviticus and Deuteronomy. Food that may be consumed according to halakha (law) is termed kosher (/?ko???r/) in English, from the Ashkenazi pronunciation of the Hebrew term kashér (????????), meaning "fit" (in this context, fit for consumption). Food that is not in accordance with law is called treif (/tre?f/; Yiddish: ????, derived from Hebrew: ??????? tr?fáh) meaning "torn."
Permitted and forbidden animals
The Torah permits only land animals that both chew the cud and have cloven hooves.[1][2] Four animals, the hare, hyrax, camel, and pig, are specifically identified as being forbidden because they possess only one of the above characteristics: the hare, hyrax and camel are hindgut fermenters, while the pig has a cloven hoof.[3]
The Torah lists winged creatures that may not be consumed, mainly birds of prey, fish-eating water-birds, and bats. The Torah permits fish residing in "the waters" (seas and rivers) only having both fins and scales.[4][5]
The Torah forbids creeping things that crawl the earth (Hebrew: sheqets)[6] and "flying creeping things",[7][8] with four exceptions: two types of locust, the beetle/cricket, and the grasshopper.[9]
Animal products
In addition to meat, products of forbidden species and from unhealthy animals were banned by the Talmudic writers.[10] This included eggs (including fish roe)[11][12][13] and milk,[14] as well as derived products such as cheese and jelly,[14] but did not include materials merely "manufactured" or "gathered" by animals, such as honey (although, in the case of honey from animals other than bees, there was a difference of opinion among the ancient writers).[15][16][17] According to the rabbinical writers, eggs from ritually pure animals would always be prolate ("pointy") at one end and oblate ("rounded") at the other, helping to reduce uncertainty about whether consumption was permitted or not.[18][19][20]
Dairy products
The classic rabbinical writers imply that milk from an animal whose meat is kosher is also kosher. As animals are considered non-kosher if after being slaughtered they are discovered to have been diseased; this could make their milk retroactively non-kosher. However, by adhering to the principle that the majority case overrules the exception, Jewish tradition continues to regard such milk as kosher, since statistically it is true that most animals producing such milk are kosher; the same principle is not applied to the possibility of consuming meat from an animal that has not been checked for disease. Rabbi Hershel Schachter, a prominent rosh yeshiva at Yeshiva University, has made the bold claim that with modern dairy farm equipment, milk from the minority of nonkosher cows is invariably mixed with that of the majority of kosher cows, thus invalidating the permissibility of consuming milk from a large dairy operation; the Orthodox Union, however, released a statement declaring the milk permissible based on some leniencies.
Human breast milk
Breast milk from a human female is permitted.[16][21][22][23][24] However, authorities assert breast milk may be consumed directly from the breasts only by children younger than four (five if the child is ill), and children older than two were only permitted to continue to suckle if they had not stopped doing so for more than three consecutive days.[16][21][22][23][25]
Cheese
The situation of cheese is complicated as hard cheese usually involves rennet, an enzyme that splits milk into curds and whey. Most forms of rennet were formerly derived from the stomach linings of animals, but currently rennet is most often made recombinantly in microbes. Because the rennet could be derived from animals, it could potentially be nonkosher. Only rennet made recombinantly, or from the stomachs of kosher animals, if they have been slaughtered according to the laws of kashrut, is kosher. If a kosher animal is not slaughtered according to the halakha, the rennet is not kosher. Rennet is not considered a meat product and does not violate the prohibition of mixing meat and dairy.[26]
Jacob ben Meir, one of the most prominent medieval rabbis, championed the viewpoint that all cheese was kosher,[citation needed] a standpoint that was practiced in communities in Narbonne and Italy.[citation needed] Contemporary Orthodox authorities do not follow this ruling, and hold that cheese requires formal kashrut certification to be kosher; some even argue this is necessary for cheese made with nonanimal rennet. In practice, Orthodox Jews, and some Conservative Jews who observe the kashrut laws, eat cheese only if they are certain the rennet itself was kosher. However, Isaac Klein's tshuva authorized the use of cheese made from non-kosher rennet, and this is widely practised by observant Conservative Jews and Conservative institutions.[27]
Eggs
Eggs are considered pareve despite being an animal product.
The Yoreh De'ah argues that if there is blood in the egg yolk, then hatching must have begun, and therefore consumption of the egg would be forbidden.[28] Modern Orthodox Jews adhere to these requirements; however, the Ashkenazi Orthodox Jews treat an egg as nonkosher if blood is found anywhere within it.[citation needed] Sephardi Orthodox Jews consider only blood in the yolk to be a problem, and treat eggs with blood in the albumen as legitimate food if the blood is removed before use.
Today, when battery eggs form the majority of available produce, many permit the egg with a blood spot following the removal of any actual blood; battery eggs are unlikely to be able to form a viable embryo.[29]
Gelatin
Gelatin is hydrolysed collagen,[30] the main protein in animal connective tissue, and therefore could potentially come from a nonkosher source, such as pig skin. Gelatin has historically been a prominent source of glue, finding uses from musical instruments to embroidery, one of the main historic emulsions used in cosmetics and in photographic film, the main coating given to medical capsule pills, and a form of food including jelly, trifle, and marshmallows; the status of gelatin in kashrut is consequently fairly controversial.
Due to the ambiguity over the source of individual items derived from gelatin, many Orthodox rabbis regard it as generally being nonkosher. However, Conservative rabbis[31] and several prominent Orthodox rabbis, including Chaim Ozer Grodzinski and Ovadia Yosef – the former Sephardic Chief Rabbi of Israel – argue that gelatin has undergone such total chemical change and processing that it should not count as meat, and therefore would be kosher.[32] Technically, gelatin is produced by separating the three strands in each collagen fiber's triple helix by boiling collagen in water. Rabbi Dr. David Sheinkopf, author of Gelatin in Jewish Law (Bloch 1982) and Issues in Jewish Dietary Laws (Ktav 1998), has published in-depth studies of the kosher uses of gelatin, as well as carmine and kitniyot.
One of the main methods of avoiding nonkosher gelatin is to substitute gelatin-like materials in its place; substances with a similar chemical behaviour include food starch from tapioca, chemically modified pectins, and carrageenan combined with certain vegetable gums – guar gum, locust bean gum, xanthan gum, gum acacia, agar, and others. Although gelatin is used for several purposes by a wide variety of manufacturers, it has started to be replaced with these substitutes in a number of products, due to the use of gelatin also being a significant concern to vegans and vegetarians.
Today manufacturers are producing gelatin from the skins of kosher fish, circumventing many of these problems.[33]
Blood
One of the main biblical food laws forbids consuming blood on account of "the life [being] in the blood". This ban and reason are listed in the Noahide Laws[34] and twice in Leviticus[35][36] as well as in Deuteronomy.[37] The Priestly Code also prohibits the eating of certain types of fat (chelev) from sacrificial land animals (cattle, sheep, and goats), since the fat is the portion of the meat exclusively allocated to God (by burning it on the altar).[38]
The classical rabbis argued that, in a number of cases, only if it is impossible to remove every drop of blood, the prohibition against consuming blood was impractical, and there should be rare exceptions: they claimed that consuming the blood that remained on the inside of meat (as opposed to the blood on the surface of it, dripping from it, or housed within the veins) should be permitted and that the blood of fish and locusts could also be consumed.[39][40][41][42]
To comply with this prohibition, a number of preparation techniques became practiced within traditional Judaism. The main technique, known as meli?ah, involves the meat being soaked in water for about half an hour, which opens pores.[43] After this, the meat is placed on a slanted board or in a wicker basket, and is thickly covered with salt on each side, then left for between 20 minutes and one hour.[43] The salt covering draws blood from the meat by osmosis, and the salt must be subsequently removed from the meat (usually by trying to shake most of it off and then washing the meat twice[43]) to complete the extraction of the blood. The type of salt used in the process is known as kosher salt.
Meli?ah is not sufficient to extract blood from the liver, lungs, heart, and certain other internal organs, since they naturally contain a high density of blood, and therefore these organs are usually removed before the rest of the meat is salted. Roasting, on the other hand, discharges blood while cooking, and is the usual treatment given to these organs. It is also an acceptable method for removing blood from all meat.[43]
Ritual slaughter
Of the rules appearing, in two groups, in Exodus, most do not express dietary laws, but one of the few dietary rules it does list is a ban on eating the meat from animals that have been "torn by beasts";[44] a related law appears in Deuteronomy's law code, totally prohibiting the consumption of anything that has died from natural causes, and even giving away or selling such things.[45] The Book of Ezekiel implies[46] that the rules about animals that die of natural causes, or are "torn by beasts", were adhered to only by the priests,[47] and were intended only for them;[48] the implication that they did not apply to, and were not upheld by, ordinary Israelites was noticed by the classical rabbis, who declared "the prophet Elijah shall some day explain this problematic passage".[49]
Traditional Jewish thought has expressed the view that all meat must come from animals that have been slaughtered according to Jewish law. These strict guidelines require the animal be killed by a single cut across the throat to a precise depth, severing both carotid arteries, both jugular veins, both vagus nerves, the trachea and the esophagus, no higher than the epiglottis and no lower than where cilia begin inside the trachea, causing the animal to bleed to death. Orthodox Jews argue that this ensures the animal dies instantly without unnecessary suffering, but many animal rights activists view the process as cruel, arguing that the animal may not lose consciousness immediately, and activists have called for it to be banned.[50][51]
To avoid tearing, and to ensure the cut is thorough, such slaughter is usually performed by a trained individual, with a large, razor-sharp knife, which is checked before each killing to ensure that it has no irregularities (such as nicks and dents); if irregularities are discovered, or the cut is too shallow, the meat is deemed not kosher. Rabbis usually require the slaughterer, known within Judaism as a shochet, to also be a pious Jew of good character and an observer of the Shabbat. In smaller communities, the shochet was often the town rabbi, or a rabbi from a local synagogue, but large slaughterhouses usually employ a full-time shochet if they intend to sell kosher meat.
The Talmud, and later Jewish authorities, also prohibit the consumption of meat from animals who were slaughtered despite being in the process of dying from disease; but this is not based on concern for the health of the eater, instead being an extension of the rules banning the meat from animals torn by beasts, and animals that die from natural causes.[52][53][54] To comply with this Talmudic injunction against eating diseased animals, Orthodox Jews usually require that the corpses of freshly slaughtered animals are thoroughly inspected. There are 70 different traditional checks for irregularities and growths; for example, there are checks to ensure that the lungs have absolutely no scars, which might have been caused by an inflammation. If these checks are passed, the meat is then termed glatt (?????), the Yiddish word meaning smooth.
Compromises in countries with animal cruelty laws that prohibit such practices involve stunning the animal to lessen the suffering that occurs while the animal bleeds to death. However, the use of electric shocks to daze the animal is often not accepted by some markets as producing meat that is kosher.[50]
Foreleg, cheeks and maw
The gift of the foreleg, cheeks and maw (Hebrew: ??????? ?????????? ?????????) of a kosher-slaughtered animal to a Kohen is a positive commandment in the Hebrew Bible.
In rabbinical interpretation a continuing application of the commandment is identified. Rabbi Yosef Karo Shulchan Aruch Yoreh Deah 61:1,[55] rules that after the slaughter of animal by a shochet (kosher butcher), the cuts of the foreleg, cheek and maw should be given to a kohen freely, without the kohen paying or performing any service.[56] This giving is required to be free of both monetary and servicial compensation (B.Bechorot 27a).
These gifts are entirely mundane ("chullin") and are not associated with all or part of the sacrificial offerings brought on the central altar in the Jerusalem temple (Mishna Hullin Ch. 10:1). Some chazal opinions maintain that consumption of the animal is forbidden before these gifts are given but halacha rules that although one may consume the meat before the gifts are given it is preferred to ensure the gifts are given prior to consumption. Furthermore, the actual foreleg, cheeks and maw of all kosher-slaughtered beef is forbidden to a non-kohen unless the kohen permits[57]
Food preparation by non-Jews
The classical rabbis prohibited any item of food that had been consecrated to an idol or had been used in the service of an idol.[58] Since the Talmud views all non-Jews as potential idolaters, and viewed intermarriage with apprehension, it included within this prohibition any food that has been cooked or prepared completely by non-Jews.[59][60] (Bread sold by a non-Jewish baker was not included in the prohibition.[59][60]) Similarly, a number of Jewish writers believed food prepared for Jews by non-Jewish servants would not count as prepared by potential idolaters, although this view was opposed by Jacob ben Asher.[61]
Consequently, modern Orthodox Jews generally believe wine, certain cooked foods, and sometimes even dairy products,[62][63][64] should be prepared only by Jews. The prohibition against drinking non-Jewish wine, traditionally called yayin nesekh (literally meaning "wine for offering [to a deity]"), is not absolute. Cooked wine (Hebrew: ??? ?????, yayin mevushal), meaning wine that has been heated, is regarded as drinkable on the basis that heated wine was not historically used as a religious libation; thus kosher wine includes mulled wine, and pasteurised wine, regardless of producer, but Orthodox Judaism regards other forms of wine as kosher only if prepared by a Jew.
Some Jews refer to these prohibited foods as akum, an acronym of Ovde Kokhavim U Mazzaloth (????? ?????? ??????), meaning "worshippers of stars and planets". Akum is thus a reference to activities that these Jews view as idolatry, and in many significant works of post-classical Jewish literature, such as the Shulchan Aruch, it has been applied to Christians in particular. However, among the classical rabbis, there were a number who refused to treat Christians as idolaters, and consequently regarded food that had been manufactured by them as being kosher;[citation needed] this detail has been noted and upheld by a number of religious authorities in Conservative Judaism, such as Rabbi Israel Silverman, and Rabbi Elliot N. Dorff.
Conservative Judaism is more lenient; in the 1960s, Rabbi Silverman issued a responsum, officially approved by the Committee on Jewish Law and Standards, in which he argued that wine manufactured by an automated process was not "manufactured by gentiles", and therefore would be kosher. A later responsum of Conservative Judaism was issued by Rabbi Dorff, who argued, based on precedents in 15th-19th century responsa, that many foods, such as wheat and oil products, which had once been forbidden when produced by non-Jews were eventually declared kosher. On this basis he concluded wine and grape products produced by non-Jews would be permissible.
Tainted food
For obvious reasons, the Talmud adds to the biblical regulations a prohibition against consuming poisoned animals.[65] Similarly, the Yoreh De'ah prohibits the drinking of water, if the water had been left overnight and uncovered in an area where there might be serpents, on the basis that a serpent might have left its venom in the water.[66] In a place where there is no suspicion of snakes, this prohibition does not apply (tosafos, beitzah 6a).
Milk and meat
Three times the Torah specifically forbids "seething" a young goat "in its mother's milk" (Exodus 23:19, Exodus 34:26, and Deuteronomy 14:21). The Talmud interprets this as a general prohibition against cooking meat and dairy products together, and against eating or deriving any benefit from such a mixture. To help prevent accidental violation of these rules, the modern standard Orthodox practice is to classify food into either being meat, dairy, or neither; this third category is more usually referred to as parev from the Yiddish word parev (??????) (also spelled parve and pareve) meaning "neutral". As the biblical prohibition uses the word "Gedi" and not "Gedi Izim", the flesh of all "Behemoth" (domestic mammals) is categorised as "meat", while that of fish and bugs is considered parve; however, rather than being considered parve, the flesh of birds and "chayot" (like deer) has been regarded by halakha (Jewish law) as meat for over 2000 years, though only by Rabbinic decree.
One of the major dietary laws that observant Jews keep of Kashruth is that dairy and meat may not be eaten at the same meal. Though it is mentioned many times in the Hebrew Bible, Rashi held that it was connected to two major ethical laws in the Jewish heritage from the original Five Books of Moses, which are, first, to respect the mother animal: Exodus 23:19 "You shall not boil a kid in its mother's milk"; and, secondly, Deuteronomy 22:6 "If you come across a bird's nest beside the road, either in a tree or on the ground, and the mother is sitting on the young or on the eggs, do not take the mother with the young." Some held these relate to the "hurt to living" (tzaar baalei chaim) statute cited throughout Jewish law, against hurting any living thing, the Mishnah Avoth 1:12, "Be a disciple of Aaron... and love all of God's animals" (chaim, living); also, "His compassion is over all of His creatures" (Psalms 145:9) and again the term is chaim, living things.
Fish and meat
The Talmud and Yoreh Deah suggest that eating meat and fish together may cause tzaraath.[67][68] Strictly Orthodox Jews thus avoid combining the two,[69][70] while Conservative Jews may or may not.[70]
Pikuach nefesh
The laws of kashrut can be broken for pikuach nefesh, i.e. when human life or health is at stake. So, for example, it is allowed for a patient to eat non-kosher food if it is essential for recovery,[71] or when one would starve if not partaking of non-kosher food.[72][73]
Kangaroo meat at the Queen Victoria Market in Melbourne
Kangaroo meat is mostly produced in Australia from wild animals and in 2010 was exported to over 55 countries worldwide.[1]
Production
Currently most kangaroo meat is sourced from wild animals as a byproduct of population control programmes.[2][3] Both the meat and the hides are sold. Although most species of macropod are protected from non-Aboriginal hunting by law, a small number of the large-sized species which exist in high numbers can be hunted by commercial hunters.[4] This policy has been criticised by some animal rights activists.[5] On the other hand, the kangaroo harvest is supported by a wide range of professional ecologists in Australia. Groups such as the Ecological Society of Australia, the Australasian Wildlife Management Society and the Australian Mammal Society have stated their support for kangaroo harvesting. Such groups argue that basing agricultural production systems on native animals rather than introduced livestock like sheep offers considerable ecological advantages to the fragile Australian rangelands and could save greenhouse gas emissions.[6][7]
Though it is impossible to determine the exact number, government conservation agencies in each state calculate population estimates each year. Nearly 40 years of refinement has led to the development of sophisticated aerial survey techniques which enable overall populations estimates to be constructed.[8] Current estimates indicate that there may be between 35 and 50 million kangaroos in Australia.[9][10] In 2002 the number of kangaroos allowed to be shot by commercial hunters was increased from 5.5 million to 7 million per year.[11] While animal rights activists protested the move, Australian farmers claimed that kangaroos were a plague after a huge increase in their numbers.[12] A 2002 report studying the grazing pressure caused by kangaroos indicated that scientific evidence is lacking that kangaroos reduce wool production or sheep carrying capacity.[13] In 2007 the national kangaroo culling quota was more than 3.5 million[14] (but significantly down on the figures earlier in the decade).
Kangaroos are protected by legislation in Australia, both state and federal. Kangaroos are harvested by licensed shooters in accordance with a strict code of practice. Meat that is exported is inspected by the Australian Quarantine and Inspection Service (AQIS).[3][9]
The quotas created in Australia are the responsibility of each state or territory government. For example, in Queensland, only the following breeds (up to 2017) were included in the quota: red kangaroo, eastern grey kangaroo, common wallaroo. "Sustainable use quotas" are typically between 10–20% of the kangaroo estimated population. Culling is only allowed in certain state areas by approved shooters. Total populations are estimated by aerial surveys and a decade of previous data. Quota numbers calculated by government and science organisations to ensure sustainability. Even though quotas are established by each state, very rarely does actual culling reach 35% of the total quotas allowed. For instance, "[i]n the 2015 harvest period, 25.9% of the commercial harvest quota (for Queensland) was utilised".[15] In NSW, private cullers had to "shoot and let lie" the carcasses of kangaroos. Drought relief laws have changed this, allowing farmers to produce kangaroo meat.[16]
Products
Kangaroo meat at an Australian supermarket
Kangaroo steak
Kangaroo with thyme served in Helsinki, Finland.
Smoked kangaroo jerky at a store in Richfield, Wisconsin, United States
The kangaroo has been historically a staple source of protein for indigenous Australians. Kangaroo meat is high in protein and low in fat (about 2%). Kangaroo meat has a very high concentration of conjugated linoleic acid (CLA) when compared with other foods. CLA has been attributed with a wide range of health benefits including anti-carcinogenic and anti-diabetes properties, in addition to reducing obesity and atherosclerosis.[3][9][17]
While Kangaroo meat has enjoyed popularity for its organic nature, little information has been available about its nutrition benefits besides articles dedicated to the value of CLA's. While basic nutritional data (total protein, fats etc.) are published worldwide, little research has been provided about the nature of the kangaroo protein and its composite amino acid profile. Of the 22 amino acids within protein, ten are vital to human and animal well-being because they can't be manufactured in the body. These are called 'essential amino acids' and the primary research on Kangaroo muscle meat nutrition is from a seminal research paper by the primary Australian Government Science organisation CSIRO in 1970.[18]
Using this research paper as a primary data source Essential Amino acids have been calculated for dried Kangaroo muscle meat (DM) and compared to various other farmed meat sources such as chicken, pork, beef and lamb.[18] By comparison to these farmed meats, Kangaroo meat is higher in Threonine, Isoleucine and Valine and lower in Arginine and Methionine-cystine amino acids. This information is invaluable in calculating balanced diets or when a subject requires an extra natural source of a specific essential amino acid.
Kangaroo meat is stronger in flavour than the meat from commercially raised food animals. It is considered to be tender. Minced (or ground) kangaroo meat may be substituted in dishes where minced beef would normally be used.
Kangaroo meat was legalised for human consumption in South Australia in 1980, and in all other Australian states in 1993.[19][dead link] Kangaroo was once limited in availability, although consumption in Australia is becoming more widespread. However, only 14.5% of Australians were reported in 2008 as eating kangaroo meat at least four times per year.[20] Many Australian supermarkets now stock various cuts of kangaroo[3][21] including fillets, steaks, minced meat and 'Kanga Bangas' (kangaroo sausages). Many Australian restaurants serve kangaroo meat.[22]
Kangaroo meat has been exported since 1959.[20] Seventy percent of kangaroo meat is exported, particularly to the European market: Germany and France.[19] It is sold in two supermarkets in the United Kingdom[21] and before a suspension on imports of kangaroo meat to Russia in 2009 it was widely used in Russian smallgoods.[23] In 2008, the industry is worth around A$250-270 million a year and provides around 4,000 jobs in Australia.[19][20]
The meat is also processed into dog food.[19] The small kangaroo farming community is a more environmentally friendly meat industry than sheep or cattle farming since kangaroos require no processed feed, are well-adapted to drought, and do not destroy the root systems of native grasses.[3] However kangaroo farming is economically unattractive due to the start up costs and inability of the farmed product to compete financially against animals that have been killed by hunters under the government quota system.[24]
Criticism and controversy
The kangaroo meat industry has attracted critical attention in Australia, the United Kingdom and the United States from animal welfare organisations. These concerns have centred on the hunting process, in which all kangaroo meat for the global market comes from kangaroos hunted in the wild. Australia's kangaroo hunting programme is the largest annual wildlife hunting programme in the world. A 2009 report from wildlife ecologist Dr Dror Ben-Ami for a University of Technology Sydney think-tank estimated that 440,000 "dependent young kangaroos" are bludgeoned or starved to death each year after their mother has been shot. The report also raised serious public health and sustainability concerns.[25][26] During the 1990s all British supermarkets agreed to stop selling kangaroo meat,[27] however German retailer Lidl and frozen food outlet Iceland have since introduced kangaroo meat once more.
Kangatarianism
Kangatarianism is a recent practice of following a diet which excludes meat except kangaroo on environmental and ethical grounds. Several Australian newspapers wrote about the neologism "kangatarianism" in February 2010, describing eating a vegetarian diet with the addition of kangaroo meat as a choice with environmental benefits because indigenous wild kangaroos require no extra land or water for farming and produce little methane (a greenhouse gas), unlike cattle.[28][29] Advocates of kangatarianism also choose it because Australian kangaroos live natural lives, eat organic food, and are killed "humanely".[30][31] For similar reasons, Australians have discussed eating only the meat of Australian feral camels ("cameltarianism").[32]
Name
There has been recent discussion from the kangaroo meat industry about attempting to introduce a specific culinary name for kangaroo meat, similar to the reference to pig meat as ham and pork, and calling deer meat venison. The motivation is to have diners thinking of the meat rather than the animal and avoiding adverse reactions to the eating of an animal considered to be cute. In 2005 the Food Companion International magazine, with support from the Kangaroo Industry Association of Australia, ran a competition hoping to find a name that would not put diners off when they saw it on a menu.[citation needed] The three-month competition attracted over 2700 entries from 41 nations, and the name australus was decided in December 2005. The name was penned by university professor Steven West, an American about to be naturalised as an Australian citizen. Other finalists for the name included kangarly, maroo, krou, maleen, kuja, roujoe, rooviande, jurru, ozru, marsu, kep, kangasaurus, marsupan, jumpmeat, and MOM (meat of marsupials).[33]
The competition is not binding on the Kangaroo Industry Association, which has not moved to adopt the new name in any official capacity.
Traditional Aboriginal use
Kangaroo formed an important part of many traditional Aboriginal diets.
Kangaroo is called Kere aherre by the Arrernte people of Central Australia:
You find kangaroos in flat country or mulga country. In the old days, people used to sic their dogs on them and spear them. The milk guts are pulled out and a wooden skewer is used to close up the carcase. Then it is tossed on top of the fire to singe the hair which is scraped off, and then it's [put in a hole and] covered up with hot earth and coals. The tail and both feet are cut off before cooking. These are put in together with the rest of the carcase.
The kangaroo is chopped up so that many people can eat it. The warm blood and fluids from the gluteus medius and the hollow of the thoracic cavity are drained of all fluids. People drink these fluids, which studies have shown are quite harmless. Kangaroos are cut in a special way; into the two thighs, the two hips, the two sides of ribs, the stomach, the head, the tail, the two feet, the back and lower back. This is the way the Arrernte people everywhere cut it up.[34]
The Anangu, Pitjantjatjara and Yankunytjatjara peoples of Central Australia call kangaroo "malu". They use malu mainly for meat (kuka) but other uses include materials for spear making. They are an important totem species. The Angas Downs Indigenous Protected Area Rangers are currently undertaking land management activities to increase this important species in the landscape. This process is named Kuka Kanyini – looking after game animals.
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Detoxification |
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Removal of unspecified toxins from the body |
Detoxification (often shortened to detox and sometimes called body cleansing) is a type of alternative medicine treatment which aims to rid the body of unspecified "toxins" – substances that proponents claim have accumulated in the body and have undesirable short-term or long-term effects on individual health. Activities commonly associated with detoxification include dieting, fasting, consuming exclusively or avoiding specific foods (such as fats, carbohydrates, fruits, vegetables, juices, herbs, or water), colon cleansing, chelation therapy, and the removal of dental fillings containing amalgam.
The concept has received criticism from scientists and health organizations for its unsound scientific basis and lack of evidence for the claims made.[1] The "toxins" usually remain undefined, with little to no evidence of toxic accumulation in the patient. The British organisation Sense About Science has described some detox diets and commercial products as "a waste of time and money",[2] while the British Dietetic Association called the idea "nonsense" and a "marketing myth".[3]
Background
Suspicions of the inefficacy of purging became widespread by the 1830s.[4] Biochemistry and microbiology appeared to support auto-intoxication theory in the 19th century, but by the early twentieth century detoxification-based approaches quickly fell out of favour.[5][need quotation to verify][6] Even though abandoned by mainstream medicine, the idea has persisted in the popular imagination and amongst alternative medicine practitioners.[7][8][9] Notions of internal cleansing had resurgence along with the rise of alternative medicine in the 1970s and following; it remains unscientific and anachronistic.[7] With the rise of the environmentalist movement, many detox diets use the diet format as a political platform to advocate for environmental ideas about pollution and toxic contamination.[10]
Types
Detox diets
Detox diets are dietary plans that claim to have detoxifying effects. The general idea suggests that most food contains contaminants: ingredients deemed unnecessary for human life, such as flavor enhancers, food colorings, pesticides, and preservatives. Scientists, dietitians, and doctors, while generally viewing "detox diets" as harmless (unless nutritional deficiency results), often dispute the value and need of "detox diets", due to lack of supporting factual evidence or coherent rationale.[2] In cases where a person suffers from a disease, belief in the efficacy of a detox diet can result in delay or failure to seek effective treatment.[11]
Detox diets can involve consuming extremely limited sets of foods (only water or juice, for example, a form of fasting[12] known as juice fasting), eliminating certain foods (such as fats) from the diet, or eliminating processed foods and alleged irritants.[13][unreliable source?] Detox diets are often high in fiber. Proponents claim that this causes the body to burn accumulated stored fats, releasing fat-stored "toxins" into the blood, which can then be eliminated through the blood, skin, urine, feces and breath. Proponents claim that things such as an altered body-odor support the notion that detox diets have an effect. The mainstream medical view is that the body has mechanisms to rid itself of toxins, and a healthy diet is best for the body.[14] Although a brief fast of a single day is unlikely to cause harm, prolonged fasting (as recommended by certain detox diets) can have dangerous health consequences or can even be fatal.[15][16]
Colon cleansing
Colon cleansing involves giving an enema (colonic) containing some salt, and sometimes coffee or herbs to remove food that, according to proponents,[citation needed] remains in the colon, producing nonspecific symptoms and general ill-health. However, the colon usually does not require any help cleaning itself.[citation needed] The practice can be potentially dangerous if incorrectly practised.[15]
Heavy metals
Practitioners may recommend detoxification as a treatment to address the notion that mercury poisoning arises from consumption of contaminated fish and from dental amalgam fillings – Quackwatch states: "Removing good fillings is not merely a waste of money. In some cases, it results in tooth loss because when fillings are drilled out, some of the surrounding tooth structure will be removed with it."[15]
"Detoxification" devices
Certain devices are promoted to allegedly remove toxins from the body. One version involves a foot-bath using a mild electric current, while another involves small adhesive pads applied to the skin (usually the foot). In both cases, the production of an alleged brown "toxin" appears after a brief delay. In the case of the foot bath, the "toxin" is actually small amounts of rusted iron leaching from the electrodes.[17] The adhesive pads change color due to oxidation of the pads' ingredients in response to the skin's moisture. In both cases, the same color-changes occur irrespective of whether the water or patch even make contact with the skin (they merely require water—thus proving the color-change does not result from any body-detoxification process).[15]
Unsound scientific basis
A 2015 review of clinical evidence about detox diets concluded: "At present, there is no compelling evidence to support the use of detox diets for weight management or toxin elimination. Considering the financial costs to consumers, unsubstantiated claims and potential health risks of detox products, they should be discouraged by health professionals and subject to independent regulatory review and monitoring."[1]
Detoxification and body cleansing products and diets have been criticized for their unsound scientific basis, in particular their premise of nonexistent "toxins" and their appropriation of the legitimate medical concept of detoxification. According to the Mayo Clinic, the "toxins" typically remain unspecified and there is little to no evidence of toxic accumulation in patients treated.[18] According to a British Dietetic Association (BDA) Fact Sheet, "The whole idea of detox is nonsense. The body is a well-developed system that has its own builtin mechanisms to detoxify and remove waste and toxins."[3] It went on to characterize the idea as a "marketing myth",[3] while other critics have called the idea a "scam"[19] and a "hoax".[20] The organization Sense about Science investigated "detox" products, calling them a waste of time and money".[2][21][22] resulting in a report that concluded the term is used differently by different companies, most offered no evidence to support their claims, and in most cases its use was the simple renaming of "mundane things, like cleaning or brushing".[2]
The human body is naturally capable of maintaining itself, with several organs dedicated to cleansing the blood and the gut.[23] Alan Boobis, a professor and toxicologist at Imperial College London, states:
The body’s own detoxification systems are remarkably sophisticated and versatile. They have to be, as the natural environment that we evolved in is hostile. It is remarkable that people are prepared to risk seriously disrupting these systems with unproven ‘detox’ diets, which could well do more harm than good.[2]
Scientific skeptic author Brian Dunning investigated the subject in 2008 and concluded that "Anyone interested in detoxifying their body might think about paying a little more attention to their body and less attention to the people trying to get their money... Why is it that so many people are more comfortable self-medicating for conditions that exist only in advertisements, than they are simply taking their doctor's advice? It's because doctors are burdened with the need to actually practice medicine. They won't hide bad news from you or make up easy answers to please you."[24]
Despite unsound scientific basis, detoxification is popular, and detoxification products and regimes have become a profitable health trend.[1] As with some other alternative medicine treatments, efficacy has been attributed to astroturfing, the placebo effect, psychosomatic improvements, or natural recovery from illness that would have occurred without use of the product.[25]
Nine most popular diets rated by experts 2017
A diet is best described as a fixed plan of eating and drinking where the type and amount of food are planned out in order to achieve weight loss or follow a particular lifestyle.
This MNT Knowledge Center article provides details on the most popular diets according to three criteria: the number of articles that cover them, how popular they seem to be, and how often we receive feedback on them.
The Atkins diet, or Atkins nutritional approach, focuses on controlling the levels of insulin in the body through a low-carbohydrate diet.
If people consume large amounts of refined carbohydrates, their insulin levels rise and fall rapidly. Rising insulin levels trigger the body to store energy from the food that is consumed, making it less likely that the body will use stored fat as a source of energy.
Therefore, people on the Atkins diet avoid carbohydrates but can eat as much protein and fat as they like.Although popular for some time, the Atkins Diet comes with certain risks. Individuals considering the Atkins Diet should speak with their doctor.
A detailed look at the Atkins diet here.
The Zone diet aims for a nutritional balance of 40 percent carbohydrates, 30 percent fats, and 30 percent protein in each meal. The focus is also on controlling insulin levels, which may result in more successful weight loss and body weight control than other approaches.
The Zone diet encourages the consumption of high-quality carbohydrates - unrefined carbohydrates, and fats, such as olive oil, avocado, and nuts.
A detailed look at the Zone diet here.
The ketogenic diet has been used for decades as a treatment for epilepsy and is also being explored for other uses. It involves reducing carbohydrate intake and upping fat intake. It sounds contrary to common sense, but it allows the body to burn fat as a fuel, rather than carbohydrates.
Healthy fats, such as those in avocados, coconuts, Brazil nuts, seeds, oily fish, and olive oil are liberally added to the diet to maintain an overall emphasis on fat.
The diet causes the break down of fat deposits for fuel and creates substances called ketones through a process called ketosis. This diet has risks including ketoacidosis for people with type 1 diabetes, however, and may result in diabetic coma and death. Although most studies are 2 years or less, there is some promising research in relation to diabetes management, metabolic health, weight loss, and body composition change.
A detailed look at the ketogenic diet here.
There are various types of vegetarian: lacto-vegetarian, fruitarian vegetarian, lacto-ovo vegetarian, living food diet vegetarian, ovo-vegetarian, pesco-vegetarian, and semi-vegetarian.
The majority of vegetarians are lacto-ovo vegetarians, in other words, they do not eat animal-based foods, except for eggs, dairy, and honey.
Studies over the last few years have shown that vegetarians have a lower body weight, suffer less from diseases, and typically have a longer life expectancy than people who eat meat.
A detailed look at vegetarianism here.
Veganism is more of a way of life and a philosophy than a diet. A vegan does not eat anything that is animal-based, including eggs, dairy, and honey. Vegans do not usually adopt veganism just for health reasons, but also for environmental, ethical, and compassionate reasons.
Vegans believe that modern intensive farming methods are bad for our environment and unsustainable in the long-term. If everybody ate plant-based food, the environment would benefit, animals would suffer less, more food would be produced, and people would generally enjoy better physical and mental health, vegans say.
A detailed look at veganism here. Various recipe books and guides are available to purchase online.
Weight Watchers focuses on losing weight through diet, exercise, and a support network.
Weight Watchers Inc. was started in the 1960s by a homemaker who had lost some weight and was concerned she might put it back on. So, she created a network of friends. Weight Watchers is a huge company, with branches all over the world.
Dieters can join either physically and attend regular meetings, or online. In both cases, there is lots of support and education available for the dieter.
A detailed look at Weight Watchers here.
The South Beach diet was started by a cardiologist, Dr. Agatston, and a nutritionist, Marie Almon. It focuses on the control of insulin levels, and the benefits of unrefined slow carbohydrates versus fast carbohydrates. Dr. Agatston devised the South Beach diet during the 1990s because he was disappointed with the low-fat, high-carb diet backed by the American Heart Association. He believed that low-fat regimes were not effective over the long-term.
A detailed look at the South Beach diet here. South beach diet books are available to buy online.
The raw food diet, or raw foodism, involves consuming foods and drinks that are not processed, are completely plant-based, and ideally organic.
Raw foodists believe that at least three-quarters of a person's food intake should consist of uncooked food. A significant number of raw foodists are also vegans and do not eat or drink anything that is animal based.
There are four main types of raw foodists: raw vegetarians, raw vegans, raw omnivores, and raw carnivores.
A detailed look at the raw food diet here.
The Mediterranean diet is Southern European, and more specifically focuses on the nutritional habits of the people of Crete, Greece, and southern Italy. Nowadays, Spain, southern France, and Portugal are also included, even though Portugal does not touch the Mediterranean Sea.
The emphasis is on lots of plant foods, fresh fruits as dessert, beans, nuts, whole grains, seeds, olive oil as the main source of dietary fats. Cheese and yogurts are the main dairy foods. The diet also includes moderate amounts of fish and poultry, up to about four eggs per week, small amounts of red meat, and low to moderate amounts of wine.
Up to one-third of the Mediterranean diet consists of fat, with saturated fats not exceeding 8 percent of calorie intake. The Mediterranean diet is the most extensively studied diet to date, with reliable research supporting its use for improving a person's quality of life and lowering disease risk.
A detailed look at the Mediterranean diet here.
Doctor Tasnime Akbaraly from Montpellier, France, and team carried out a study that found that the Western style diet, which is high in sweet and fried foods, raises a person's risk of dying early. They published their findings in the American Journal of Medicine.
Akbaraly said "The impact of diet on specific age-related diseases has been studied extensively, but few investigations have adopted a more holistic approach to determine the association of diet with overall health at older ages. We examined whether diet, assessed in midlife, using dietary patterns and adherence to the Alternative Healthy Eating Index (AHEI), is associated with aging phenotypes, identified after a mean 16-year follow-up."
The team found that study participants who strayed from the "Alternative Healthy Eating Index" had a considerably higher risk of cardiovascular and non-cardiovascular death.
We picked linked items based on the quality of products, and list the pros and cons of each to help you determine which will work best for you. We partner with some of the companies that sell these products, which means Healthline UK and our partners may receive a portion of revenues if you make a purchase using a link(s) above.
There is no perfect weight loss diet.
Different diets work for different people, and you should pick one that suits your lifestyle and tastes.
The best diet for you is the one that you can stick to in the long term.
See also
