Low Carb (e.g., Atkins)
Advises lots of protein, mostly in the form of meat at every meal, and restricts carbohydrates. Thirty percent of your calories will come from protein, 50 percent from fat, and about 20 percent from carbs, especially good ones like veggies and fruit.
Low Fat (e.g., Weight Watchers)
Emphasizes grains, fruits, and vegetables and allows modest servings of meat. Portion control is key. About 50 percent of your calories will come from carbohydrates, 30 percent from fat, and 20 percent from protein.
Balances carbohydrates, fat, and protein, theoretically to stabilize hormones that trigger hunger and weight gain. Thirty percent of the calories you eat will be fat, 40 percent carbohydrates, and 30 percent protein.
Prescribes grains, vegetables, and sources of healthy fats such as olive oil and nuts. About 45 percent of your calories on this plan will come from carbohydrates, 35 percent from fat, and 20 percent from protein.
Is an extremely low-fat vegetarian diet that recommends forgoing nuts, meat, and fish. Roughly 70 percent of your calories will come from carbohydrates, 20 percent from protein, and 10 percent from fat.
Number of dieters: Low carb, 109; low fat, 104; Mediterranean, 109.
Pounds lost at six months: Low carb, 14; low fat, 10; Mediterranean, 10.
Final loss (two years): Low carb, 12 pounds; low fat, 7; Mediterranean, 10.
The details: Most of the dieters in this 2008 study published in The New England Journal of Medicine (and paid for in part by the Atkins Research Foundation) were men. The women actually lost more pounds on the Mediterranean approach, but the finding wasn't conclusive. As is true in most diet studies, weight loss peaked at around six months, after which dieters began to put pounds back on. All groups saw improvements in cholesterol, insulin, glucose, triglyceride, and blood pressure levels.
Number of dieters: Low carb, 77; low fat, 79; Zone, 79; Ornish, 76.
Pounds lost at six months: Low carb, 14; low fat, 9; Zone, 6; Ornish, 6.
Final loss (one year): Low carb, 10 pounds; low fat, 6; Zone, 4; Ornish, 5.
The details: Low-carb (Atkins) was ahead at six months in this 2007 study published in the Journal of the American Medical Association. But after a year, the difference in the amount of weight lost wasn’t considered significant between the low-carb, low-fat and Ornish diets (the Zone group came out last). However, low-carb dieters saw their heart disease risk factors—blood pressure, cholesterol, triglyceride levels—improve at least as much as the people on the heart-healthy low-fat and Ornish diets. Again, most of the pounds were shed in the first few months, with many people gaining back some weight. By the end, in fact, many in all four groups had stopped following their prescribed diets closely.
Number of dieters: Low fat, 24; exercise, 19.
Pounds lost at six weeks: Low fat, 6; exercise, 2.
Final loss (three months): Low fat, 9 pounds; exercise, 3.
The details: In a 2008 study published in the Journal of Exercise Physiology, a group of dieters followed a low-fat plan, while exercisers stuck to their usual eating patterns and worked out at least three days a week for 50 to 60 minutes at a gym. Though the dieters shed more pounds, some of the loss was in the form of calorie-burning muscle (the exercisers kept their muscle mass). As the researchers point out, muscle is key to helping dieters maintain weight loss. The results demonstrate the need to combine exercise and dieting.
Low Carb and Exercise
A low-carb diet consistently produced the greatest weight loss in the first six months of dieting, so this plan—combined with exercise—seems to be a good place to start. "I'm a proponent of that approach if it means you'll eat fewer junky carbs," says Christopher Gardner, PhD, associate professor of medicine at Stanford University and lead author of the study in Match 2 (above ). But Gardner says dieters may need to try more than one plan before they find success. "We are all so different—a diet that works for me may not work for you," he says. In fact, each of the diets had a few adherents who managed to lose 30 to 40 pounds. "What's more important than diet type is how closely you can adhere to it," says Gardner.
The truth is, says Meir Stampfer, MD, of the Harvard School of Public Health and an author of the Match 1 study, "there is more than one way to go for weight loss, so don't get discouraged."