Study: Low-carb diet more effective overall

ATLANTA — A low-carb diet and a Mediterranean-style regimen helped people lose slightly more weight than a traditional low-fat diet in one of the longest and largest studies to compare the dueling weight-loss techniques.

A bigger surprise: The low-carb diet improved cholesterol more than the other two. Some critics had predicted the opposite.

The study, published Thursday in The New England Journal of Medicine, was partly financed by the Atkins Research Foundation, but the foundation played no role in the study's design or reporting of the results, said the lead author, Iris Shai of Ben-Gurion University of the Negev.

The researchers followed 322 dieters, 277 men and 45 women. The dieters were assigned to follow one of three types of diets — a diet with about 30 percent fat, based on American Heart Association guidelines; a Mediterranean diet; and a low-carbohydrate diet based on the Atkins diet plan.

The research was done in a controlled environment — an isolated nuclear-research facility in Israel. The dieters consistently ate lunch, the largest meal of the day, in the company cafeteria, where food was color-coded to help them comply with their eating plan.

The biggest weight loss happened in the first five months of the diet — low-fat and Mediterranean dieters lost about 10 pounds, and low-carbohydrate dieters lost 14 pounds.

By the end of two years, all the dieters had regained some, but not all, of the lost weight. The low-fat dieters showed a net loss of six pounds, and the Mediterranean and low-carbohydrate dieters both lost about 10 pounds.

Researchers said the weight-loss results sound modest, but they had resulted in improvements in the ratios of good to bad cholesterol and other health markers.

There were subtle differences in the three diets studied. Men did better on the low-carbohydrate diets, losing 11 pounds compared with 9 pounds for the Mediterranean diet. Women fared best on the Mediterranean diet, losing 14 pounds compared with 5 pounds on the low-carbohydrate plan.

Critics have long acknowledged that an Atkins-style diet could help people lose weight but feared that over the long term, it may drive up cholesterol because it allows more fat.

But the low-carb approach seemed to trigger the most improvement in several cholesterol measures, including the ratio of total cholesterol to HDL, the "good" cholesterol.