Premenopausal women who were assigned to follow the Atkins diet for one year lost more weight when compared to women who were assigned to follow the Zone, Ornish and LEARN diets, according to a study in the March 7 issue of JAMA.

Overweight and obesity are well-documented problems in the United States. National dietary weight loss guidelines (a diet low in calories and fat, high in carbohydrates) have been challenged, particularly by supporters of low-carbohydrate diets.

However, limited evidence has been available to effectively evaluate other diets, according to background information in the article.

Christopher D. Gardner, Ph.D., of Stanford University Medical School, Stanford, Calif., and colleagues examined the effects of four diets-3 popular and substantially different diets and 1 diet based on national guidelines-representing a spectrum of carbohydrate intake, on weight loss and related metabolic variables in overweight and obese premenopausal women.

 

The diets were Atkins (very low in carbohydrate), Zone (low in carbohydrate), LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition; low in fat, high in carbohydrate, based on national guidelines), and Ornish (high in carbohydrate).

The study, which included 311 overweight/obese (body mass index, 27-40) nondiabetic, premenopausal women, was conducted from February 2003 to October 2005. Participants were randomly assigned to follow for 12 months the Atkins, Zone, LEARN or Ornish diets and received weekly instruction for 2 months, then an additional 10-month follow-up.

The researchers found that weight loss was greater for women in the Atkins diet group compared with the other diet groups at one year. 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.

At 12 months, measurements for lipids and levels of insulin, glucose and blood pressure for the Atkins group were comparable with or more favorable 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)," researchers write,

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 warn. 

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