Satiety after preloads with different amounts of fat and carbohydrate: implications for obesity.

High intake of dietary fat may be key in both the etiology and maintenance of obesity. Because a reduction in the proportion of energy derived from fat will be accompanied by an increase in the proportion of energy derived from carbohydrate, this study compared the effects of these macronutrients on eating behavior in obese and lean individuals. The effects of different amounts of fat and carbohydrate, covertly incorporated into yogurt preloads, on subsequent food intake, hunger, and satiety were assessed. A group of 12 normal-weight men, unconcerned about eating and body weight (unrestrained), accurately compensated for the energy in the preloads regardless of the nutrient composition. Other groups (n = 12 per group), including normal-weight restrained men and normal-weight and obese restrained and unrestrained females, did not show such orderly energy compensation; joule-for-joule, the high-fat preloads suppressed intake at lunch less than did high-carbohydrate preloads. These results suggest that a relative insensitivity to the satiating effect of fat could be involved in the development and maintenance of obesity.