By Dr. Barry Sears
The two major problems that plague diet studies are (1) they are too short in duration, and (2) the subjects rarely maintain the diet they were supposed to follow. In a recent study published in the Journal of Nutrition with Don Layman of the University of Illinois as lead author, both these problems were overcome. In this study done at two separate locations, 130 obese men and women were placed on iso-caloric diets (1,700 calories for females and 1,900 calories for males). Half were following the Zone Diet guidelines (30 percent protein, 40 percent carbohydrates, and 30 percent fat), and other half were following the USDA Food Pyramid dietary guidelines (15 percent protein, 55 percent carbohydrates and 30 percent fat). The subjects had weekly educational meetings to maintain the appropriate diets.
At the end of one year, those on those on the Zone Diet had lost 38 percent more fat mass than those on the USDA Food Pyramid diet. The LDL levels were the same in both groups, but the triglyceride levels were much lower and the HDL higher for those following the Zone Diet. As Don Layman stated, “studies that report there is no difference among diets also report that subjects were not carefully following the diets. It is very important to realize the difference between diet compliance and diet effectiveness.” Bottom line—the Zone Diet is once again more effective than the usual low-fat, high-carbohydrate diet where virtually everyone fails to maintain initial weight loss.