The Atkins diet has always been controversial, mainly because it flies in the face of medical wisdom by recommending that followers drastically cut down on carbohydrates such as bread, pasta and sugar.

Now, a new study finds that women who follow the Atkins diet for one year lose significantly more weight than those following the popular Zone, Ornish or LEARN diets.

Obesity has reached near-epidemic proportions in the United States over the past several decades — a time in which the federal government has been urging everyone to cut down on calories and fat in favor of more carbohydrates. Could a carbohydrate-heavy diet be causing obesity instead of curing it?

For their study, published in the March 7, 2007 issue of JAMA, Christopher D. Gardner, Ph.D., of Stanford University Medical School and colleagues, examined the effects of four weight loss diets that call for varying amounts of carbohydrates. These were Atkins (very low in carbohydrate), Zone (low in carbohydrate), LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition; low in fat, high in carbohydrate) and Ornish (high in carbohydrate).

Three hundred eleven overweight or obese women in the study were randomly assigned to one of the four diets for 12 months.

Besides weight loss, the women were measured for lipid profile (including cholesterol and triglyceride levels), percentage of body fat, waist-hip ratio, fasting insulin and blood sugar levels, and blood pressure.

Researchers found that the Atkins diet group lost more weight than the others. Average 12-month weight loss was 10.4 lbs for Atkins, 3.5 lbs. for Zone, 5.7 lbs. for LEARN, and 4.8 lbs. for Ornish. Measurements for lipids and levels of insulin, glucose and blood pressure for the Atkins group were as good or better than the other diet groups.

"Concerns about adverse metabolic effects of the Atkins diet were not substantiated within the 12-month study period. It could not be determined whether the benefits were attributable specifically to the low carbohydrate intake vs. other aspects of the diet (e.g., high protein intake). While questions remain about long-term effects and mechanisms, these findings have important implications for clinical practice and health care policy. Physicians whose patients initiate a low-carbohydrate diet can be reassured that weight loss is likely to be at least as large as for any other dietary pattern and that the lipid effects are unlikely to be of immediate concern. As with any diet, physicians should caution patients that long-term success requires permanent alterations in energy intake and energy expenditure, regardless of macronutrient content," the authors conclude.