Consistency most important with any diet

Blaming the type of diet one follows for failing to lose weight is convenient. But a comparison of four popular weight-loss diets that volunteers tried for one year showed that sticking with a diet was more important than the type of diet when it came to losing weight.

The study was funded in part by the Agricultural Research Service (ARS)--the chief scientific research agency of the U.S. Department of Agriculture. The study was featured in the March issue of Agricultural Research magazine, published by ARS. The issue highlights ARS obesity research.

Study co-authors Ernst J. Schaefer and Joi A. Gleason are at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, and Michael L. Dansinger is at the Tufts-New England Medical Center. Both centers are in Boston, Mass.

The study compared the relative merits of the Atkins (carbohydrate restriction), Ornish (fat restriction), Weight Watchers (calorie and portion size restriction), and Zone (high-glycemic-load carbohydrate restriction and increased protein) diets. The findings were published in the Journal of the American Medical Association.

The researchers randomly assigned 160 overweight or obese volunteers to follow one of the four diets. During the first two months, all participants were provided with diet-specific counseling. Among “completers” of the entire 12-month regimen, all four diets led to modest, but significant, weight reductions and a 10-percent improvement in the balance of “good” HDL and “bad” LDL cholesterol levels.

Only about half of the volunteers completed the program while on what the authors considered to be the more extreme diet plans: Atkins and Ornish. In contrast, nearly two-thirds were able to complete the more moderate diet plans: Weight Watchers and Zone.

The study findings show the importance of adopting a caloric-restriction diet best suited to one’s food preferences, lifestyle and health status. The authors concluded that the strongest predictor of volunteers’ weight loss was not the type of diet, but their compliance with it.