High-fat foods are readily overeaten. This could be because fat increases the palatability and energy density of foods or because fat has a low satiety value compared with carbohydrate. In several studies examining the effects of preloads that varied in fat and carbohydrate content on subsequent food intake, there was little difference in the effects of fat and carbohydrate on satiety. A dose-response preloading paradigm gives the most sensitive index of satiety. In one such test it was found that the effects of yogurts varying in fat or carbohydrate content did not differ in normal-weight, unrestrained men. However, in obese individuals or those concerned with body weight, fat in the yogurts was less effective in reducing subsequent food intake than carbohydrate. More studies are required to determine whether this small, but significant, insensitivity to energy from fat affects the regulation of food intake and body weight.