ATLANTA -- The Atkins diet may have proved itself. The low-carb diet and a Mediterranean-style regimen helped people lose more weight than a traditional low-fat diet in one of the longest and largest studies to compare dueling weight-loss techniques.

A bigger surprise: The low-carb diet improved cholesterol more than the Mediterranean or low-fat diet. Some critics had predicted the opposite. The study concluded that each diet had some success in weight loss and improving cholesterol.

Atkins reaction: "It is a vindication," said Abby Bloch of the Dr. Robert C. and Veronica Atkins Foundation, a philanthropy group that honors the Atkins diet's creator and was the study's main funder. The foundation, however, 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. Experts said the study -- being published today in the New England Journal of Medicine -- was highly credible.

Study at a glance: The research was done in a controlled environment -- at an isolated nuclear-research facility in Israel. There, 322 participants, mostly men, got their main meal of the day, lunch, at a central cafeteria. They were counseled on how to stick to those diets at breakfast and dinner. They filled out questionnaires about what they ate for those meals.

What they ate: The low-fat diet restricted calories and cholesterol and focused on low-fat grains, vegetables and fruits as options. The Mediterranean diet had similar calorie, fat and cholesterol restrictions, emphasizing poultry, fish, olive oil and nuts. The low-carb diet set limits for carbohydrates but none for calories or fat. It urged dieters to choose vegetarian sources of fat and protein.

Weight-loss results: Average weight loss for those in the low-carb group was 10.3 pounds after two years. Those in the Mediterranean diet lost 10 pounds, and those on the low-fat regimen dropped 6.5.

Cholesterol results: 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. For example, someone with total cholesterol of 200 and an HDL of 50 would have a ratio of 4 to 1. The optimum ratio is 3.5 to 1, according to the American Heart Association. The ratio declined 20 percent in people on the low-carb diet, compared with 16 percent in those on the Mediterranean and 12 percent in low-fat dieters.

The findings

Winning diets: Low-carb and Mediterranean-style diets took off more pounds and better lowered cholesterol than a low-fat diet in a two-year study.
Caveats: Experts say the low-fat diet in the experiment allowed more fat than the American Heart Association recommends.