Effect of calories on appetite for palatable food in obese and nonobese humans.

Palatable food stimuli were presented to 11 obese and 11 nonobese male human subjects (in three experiments) 1 hr after ingestion of 900-calorie liquid lunches and (on separate days) indentically tasting 450-calorie liquid lunches of equal volume. Salivary responses to the presentation of the stimuli (i.e., appetite) by the nonobese were inhibited by the high-calorie meal, but those by the obses were less inhibited. Hunger ratings were unaffected by calories in either group. Food stimuli were rated as more appetizing by the nonobese after high-calorie meals, but not so by the obese. Parallels with animal findings suggest that salivary responses reflect lateral hypothalamic activity.