Some previous studies have found that low carbohydrate diets like Atkins work better than a traditional low-fat diet. But the new research found that the key to losing weight boiled down to a basic rule — calories in, calories out.
“The hidden secret is it doesn’t matter if you focus on low-fat or low-carb,” said Dr. Elizabeth Nabel, director of the National Heart, Lung and Blood Institute, which funded the research.
Limiting the calories you consume and burning off more calories with exercise is key, she said.
The study, which appears in Thursday’s New England Journal of Medicine, was led by Harvard School of Public Health and Pennington Biomedical Research Center in Louisiana.
Researchers randomly assigned 811 overweight adults to one of four diets, each of which contained different levels of fat, protein and carbohydrates.
Though the diets were twists on commercial plans, the study did not directly compare popular diets. The four diets contained healthy fats, were high in whole grains, fruits and vegetables and were low in cholesterol.
Nearly two-thirds of the participants were women. Each dieter was encouraged to slash 750 calories a day from their diet, exercise 90 minutes a week, keep an online food diary and meet regularly with diet counselors to chart their progress.
There was no winner among the different diets; reduction in weight and waist size were similar in all groups.
People lost 13 pounds on average at six months, but all groups saw their weight creep back up after a year. At two years, the average weight loss was about 9 pounds while waistlines shrank an average of 2 inches. Only 15 percent of dieters achieved a weight-loss reduction of 10 percent or more of their starting weight.
Dieters who got regular counseling saw better results. Those who attended most meetings shed more pounds than those who did not — 22 pounds compared with the average 9 pound loss.