Effect of Diet Composition on the Hyperinsulinemia of Obesity

During two successive three-week periods, seven obese subjects were fed isocaloric diets, the first low, the second high in carbohydrate. In all, basal plasma insulin levels decreased 50 per cent on the low-carbohydrate diet and increased on the high-carbohydrate diet. Three obese subjects were fed, during three successive four-week periods, 1500-calorie diets with high, then low, and then high-carbohydrate content. Basal plasma insulin levels were significantly reduced on the low-carbohydrate diet. Refeeding of the high-carbohydrate diet, despite continued weight loss, resulted in markedly increased basal plasma insulin. In both protocols, most patients also exhibited a decreased insulin secretory response to oral glucose when on a low intake of carbohydrate and an increased response on a high intake. Thus the hyperinsulinemia characteristic of obesity may be a result, in part, of dietary factors rather than exclusively a consequence of the insulin antagonism associated with obesity.