What's the best way to lose weight - load up on proteins and cut carbohydrates? Keep the good carbs and just trim fats? Or build "healthful" fats into your diet?
Scientists now say it doesn't matter as long as you consume fewer calories.
A new study in The New England Journal of Medicine tested four different diets and found that participants lost similar amounts of weight on each of them.
In the extensive two-year study, investigators randomly assigned more than 800 overweight participants to follow one of four heart-healthy diets, each emphasizing a different combination of carbohydrates, protein and fat.
All replaced saturated with unsaturated fat and emphasized whole grains, fruits and vegetables. But a diet that stressed protein, for instance, included more servings of lean fish and chicken, while a diet higher in fat included more olive oil.
All the regimens had similar calories.
Regardless of diet, participants tended to lose the same amount of weight. At six months, they had lost an average of 13 pounds, and they maintained a 9-pound reduction after two years.
"On average, no one diet is better than another for weight loss," said Dr. Frank M. Sacks, professor of cardiovascular disease prevention at the Harvard School of Public Health and lead author of the study.
"The determining factor ended up being calories," he said. "It really comes down to people doing what is most effective for themselves, as long as [the diets] are healthy and prevent heart disease."
The investigation was a joint effort by researchers from Harvard; the Pennington Biomedical Research Center at the University of Louisiana, Baton Rouge; and the National Heart Lung and Blood Institute, a division of the National Institutes of Health.
Local weight loss experts called the findings significant and said they confirm a common-sense approach to weight loss.
"It is very commendable," said Dr. Soren Snitker, assistant professor at the University of Maryland School of Medicine. "I agree with them that we should not get hung up on fat, carbohydrate and protein contents. But this is about producing a diet that is palatable and culturally relevant to the patient. There are actually several ways of getting to your goal."
Nevertheless, this is not the diet study to end all others, said Dr. Lawrence J. Cheskin, director of the Johns Hopkins Weight Management Center.
