Are the Fad Diets Healthy?

Everyone has heard the story about the friend who fits back into her wedding dress after a diet of bacon, cheese, and sausage. Or the colleague who has trimmed down by "eating for her blood type." Real Simple asked experts to weigh in on recent diet trends: Are they good for you, or too good to be true?

The Atkins Diet, by Robert C. Atkins, M.D.

Premise: A high-protein, high-fat, low-carbohydrate diet. It limits the majority of carbohydrates (such as bread, pasta, grains, and rice), most fruits, and many vegetables (such as yams, carrots, and peas). It allows you to eat plenty of high-fat protein, such as bacon, cheese, and steak.
Expert opinion: "This diet promotes high-fat proteins and lacks the important nutrients found in fruits, vegetables, and whole grains, as well as carbohydrates, which give you energy," says Heidi Skolnik, M.S., C.D.N., the nutritionist for the New York Mets and the Women's Sports Medicine Center in New York City. "It's not a healthy diet for the long term."

The Zone, by Barry Sears, Ph.D., with Bill Lawren

Premise: A high-protein, low-carbohydrate diet in which every meal and snack is composed of a ratio of 40 percent carbohydrates, 30 percent protein, and 30 percent fat. (The USDA Food Pyramid, by comparison, says a well-balanced meal should consist of nearly 50 percent carbohydrates, with fat consumed "sparingly.") This supposedly puts your body in a special "zone" that expedites weight loss.
Expert opinion: "Although it's good to have a balance of all three at each meal, saying you need a specific ratio is a gimmick," says Leslie Bonci, R.D., director of nutrition at the Pittsburgh Center for Sports Medicine. "Besides the fact that it's difficult to make every meal you eat fit that ratio, there's nothing magical about that particular combination that's going to make you lose weight."

The Carbohydrate Addict's Diet, by Rachael F. Heller, Ph.D., and Richard Heller, Ph.D.

Premise: You decrease the number of times a day you eat carbohydrates; the rest of your meals are high-protein.
Expert opinion: "Though it's a good idea to limit any food you tend to overeat, restricting carbohydrates to one time in the day can often lead people to binge," says Bonci. "And you need carbohydrates as an available energy source for the body throughout the day."

Somersize program, by Suzanne Somers

Premise: A high-protein diet that limits sugars and starches and has detailed rules about how to combine foods. For example, you eat proteins and fats separately from carbohydrates, eat fruit on an empty stomach, and wait three hours between meals if switching from a protein-fat meal to a carbohydrate meal.
Expert opinion: "There's no scientific proof that you lose more weight when foods are eaten — or not eaten — in specific combinations," says Skolnik. "All those parameters simply help people limit how much they're eating, which is what may lead to weight loss."

Sugar Busters!, by H. Leighton Steward; Sam S. Andrews, M.D.; Morrison C. Bethea, M.D.; and Luis A. Balart, M.D.

Premise: A high-protein diet that limits simple carbohydrates, sugars, and starches, such as pasta and potatoes. It doesn't allow fruit to be eaten in combination with meat.
Expert opinion: "If you cut out sugar and starch, you'll lose weight," says Skolnik. "But it's usually not a good idea to cut food groups out completely - just limit them to trim down."

Eat Right 4 Your Type, by Peter J. D'Adamo, with Catherine Whitney

Premise: Your blood type determines which foods you can and can't eat.
Expert opinion: "It's preposterous. There's no scientific research to show that your blood type impacts what you should and shouldn't eat," says Bonci.

Eat More, Weigh Less, by Dean Ornish, M.D.

Premise: A low-fat vegetarian diet that focuses on eating beans, legumes, fruits, vegetables, grains, and a limited number of nonfat dairy products. It avoids meats, oils, high-fat dairy products, sugar, and alcohol.
Expert opinion: "This healthy, well-rounded plan has a lot of research behind it and has been beneficial, especially for those with heart disease," says Skolnik. "If you're open to eating this kind of vegetarian diet, it can work for you. However, the average person might find it somewhat limiting."

Body for Life, by Bill Phillips and Michael D'Orso

Premise: You eat six meals a day for six days, and for each you pick one of 18 lean proteins and one of 18 carbohydrates from a list of "authorized foods," adding a serving of "authorized vegetables" to at least two meals. Just one tablespoon of unsaturated fat is allowed per day. On the seventh day, you eat whatever you want. The diet requires an aerobic workout three times a week and weight training on three other days.
Expert opinion: "In general, this plan gets a thumbs-up," says Bonci. "Eating smaller, frequent meals is a good weight-loss tactic, and this diet teaches you about balance, because it doesn't focus on one particular nutrient but includes a mix of them."

8 Minutes in the Morning, by Jorge Cruise

Premise: A diet-and-exercise program that guarantees weight loss in four weeks. Each day, you do eight minutes of strength training in the morning and you eat three servings of fats, three of protein, four of complex carbohydrates, two of dairy, one fruit, two treat foods, and eight glasses of water. If you're still hungry, you can choose from a list of unlimited vegetables.
Expert opinion: "It's a well-rounded diet because it doesn't promote one food group over the other. However, it's a bit too low in calories for some people," says Bonci. "And doing only eight minutes of strength training isn't going to help with weight loss as much as aerobic exercise will."

Eat, Drink, and Be Healthy, by Walter C. Willett, M.D., with the Harvard School of Public Health

Premise: The author criticizes the USDA Food Pyramid and says the 6 to 11 servings of carbohydrates it recommends and its suggestion to use all fats sparingly are the reason weight gain is such a problem in the United States. He has created his own Health Eating Pyramid, which emphasizes whole-grain carbohydrates, lean protein, vegetables, and unsaturated fats, and limits starches and sugars. He also suggests taking a multivitamin.
Expert opinion: "There is good science behind what is being offered here," says Skolnik. "It's healthy because the author is refining the existing pyramid and helping people understand the difference in the quality of foods that they eat. It teaches you to make healthier choices within each food group."