The theory behind low-carbohydrate diets is that if dieters avoid
foods containing carbohydrate—that is, starches or sugars—they
will shed pounds. Such diets eliminate or dramatically restrict
the intake of fruit, fruit juice, starchy vegetables, beans, bread,
rice, cereals, pasta and other grain products, and all other foods
containing carbohydrate, leaving a limited diet of foods that contain
primarily fat and protein: meat, cheese, nonstarchy vegetables,
and very little else. As the diet proceeds, the carbohydrate restriction
relaxes somewhat, but fatty, high-protein foods continue to dominate
the dieter’s plate.
Despite anecdotal accounts of seemingly dramatic weight loss, the effect of low-carbohydrate diets on body weight is similar to that of other weight-reduction diets. In research studies at the University of Pennsylvania and at the Philadelphia Veterans Affairs Medical Center, the average participant lost weight during the first six months on a low-carbohydrate diet, but regained some of this weight during the next six months so that the net weight loss after one year (15.8 pounds in the University of Pennsylvania study and 11.2 pounds in the VA study) was not significantly different from that seen with other diets used for comparison. This degree of weight loss is not greater than that which occurs with programs using low-fat, vegetarian diets. In Dean Ornish’s program for reversing heart disease, for example, a combination of a low-fat, vegetarian diet and exercise led to an average weight loss of 22 pounds in the first year, along with dramatic reductions in cholesterol levels and reversal of existing heart disease. Five years later, much of that benefit had been retained. Studies of whether weight loss from low-carbohydrate diets is maintained for more than one year have not been performed.
In a one-year clinical trial reported in JAMA in 2005, researchers randomly assigned 160 overweight individuals to one of four popular diets. Participants assigned to the Atkins diet lost 2.1 kilograms, while Weight Watchers dieters lost 3.0 kilograms, Zone dieters lost 3.2 kilograms, and dieters following the Ornish program lost 3.3 kilograms.
A review of 107 research studies on various low-carbohydrate, high-protein weight-loss diets concluded that weight loss on these diets is not due to any special effect of restricting carbohydrate; rather, weight loss depended on the extent to which the dieters’ caloric intake fell and how long they continued with their regimens. Other reports have also found calorie reduction to be the most important factor in weight loss, with no special weight-loss advantage from the restriction of carbohydrates.
A review on the safety of low-carbohydrate diets notes that Atkins-type diets are at a greater risk for being nutritionally inadequate and raise the issue of potential long-term health effects.
Despite anecdotal accounts of seemingly dramatic weight loss, the effect of low-carbohydrate diets on body weight is similar to that of other weight-reduction diets. In research studies at the University of Pennsylvania and at the Philadelphia Veterans Affairs Medical Center, the average participant lost weight during the first six months on a low-carbohydrate diet, but regained some of this weight during the next six months so that the net weight loss after one year (15.8 pounds in the University of Pennsylvania study and 11.2 pounds in the VA study) was not significantly different from that seen with other diets used for comparison. This degree of weight loss is not greater than that which occurs with programs using low-fat, vegetarian diets. In Dean Ornish’s program for reversing heart disease, for example, a combination of a low-fat, vegetarian diet and exercise led to an average weight loss of 22 pounds in the first year, along with dramatic reductions in cholesterol levels and reversal of existing heart disease. Five years later, much of that benefit had been retained. Studies of whether weight loss from low-carbohydrate diets is maintained for more than one year have not been performed.
In a one-year clinical trial reported in JAMA in 2005, researchers randomly assigned 160 overweight individuals to one of four popular diets. Participants assigned to the Atkins diet lost 2.1 kilograms, while Weight Watchers dieters lost 3.0 kilograms, Zone dieters lost 3.2 kilograms, and dieters following the Ornish program lost 3.3 kilograms.
A review of 107 research studies on various low-carbohydrate, high-protein weight-loss diets concluded that weight loss on these diets is not due to any special effect of restricting carbohydrate; rather, weight loss depended on the extent to which the dieters’ caloric intake fell and how long they continued with their regimens. Other reports have also found calorie reduction to be the most important factor in weight loss, with no special weight-loss advantage from the restriction of carbohydrates.
A review on the safety of low-carbohydrate diets notes that Atkins-type diets are at a greater risk for being nutritionally inadequate and raise the issue of potential long-term health effects.
