The effects of specific nutritional factors on ghrelin secretion have not been investigated in humans. Therefore, we assessed ghrelin responses to a high-carbohydrate meal (1217 kcal with 77% carbohydrates, 10% protein, and 13% lipids) and to an isocaloric high-fat meal (15% carbohydrates, 10% proteins, and 75% lipids) in 14 nonobese healthy women. Eleven subjects also rated their hunger feelings on visual analog scales. Circulating ghrelin abruptly fell after both meals, but, after the carbohydrate meal, its maximum percent decrease was significantly greater than after the fat meal (P = 0.02). Plasma insulin and glucose levels rose after the meals, but their increases were significantly higher after the carbohydrate meal than after the fat meal. No significant change was observed in circulating leptin after both meals. Moreover, compared with the fat meal, the carbohydrate meal had a significantly greater suppressant effect on hunger feelings. Plasma ghrelin changes were significantly associated with hunger changes (P < 0.007). These findings show that circulating ghrelin is differently suppressed by diet manipulations. The mechanisms responsible for such a phenomenon and its possible implication in the physiology of human satiety remain to be elucidated.

Background: Hedonic hunger refers to consumption of food just for pleasure and not to maintain energy homeostasis. In this condition, the subject eats also when not in a state of short-term energy depletion, and food is consumed uniquely because of its gustatory rewarding properties. The physiological mechanisms underlying this eating behavior are not deeply understood, but endogenous rewarding mediators like ghrelin and endocannabinoids are likely involved. Objective and Design: To explore the role of these substances in hedonic eating, we measured changes in their plasma levels in eight satiated healthy subjects after ad libitum consumption of highly palatable food as compared with the consumption of nonpalatable food in isoenergetic amounts with the same nutrient composition of the palatable food. Results: The consumption of food for pleasure was characterized by increased peripheral levels of both the peptide ghrelin and the endocannabinoid 2-arachidonoyl-glycerol. Levels of the other endocannabinoid anandamide and of anandamide-related mediators oleoylethanolamide and palmitoylethanolamide, instead, progressively decreased after the ingestion of both highly pleasurable and isoenergetic nonpleasurable food. A positive correlation was found between plasma 2-arachidonoyl glycerol and ghrelin during hedonic but not nonhedonic, eating. Conclusions: The present preliminary findings suggest that when motivation to eat is generated by the availability of highly palatable food and not by food deprivation, a peripheral activation of two endogenous rewarding chemical signals is observed. Future research should confirm and extend our results to better understand the phenomenon of hedonic eating, which influences food intake and, ultimately, body mass.