Gastrointestinal correlates of the development of hunger in man.

Experiments were carried out on ten healthy male volunteers to investigate the relationship between the return of hunger after a meal and gastric emptying, blood glucose levels and small intestinal motor patterns. There was a significant correlation between the postprandial increase in hunger ratings and the time for 90% of the meal to empty (r = 0.75, p less than 0.02): hunger ratings started to increase in three subjects when over 40% of the food still remained in the stomach, and they continued to increase in all subjects even when the meal had ceased to empty from the stomach. These results suggest the reduction of gastric distension may have a permissive role in the development of hunger after a meal. The increase in hunger was not related to any consistent change in plasma glucose concentration. Finally, the postprandial onset of a fasting motor pattern (phase-III-like activity) always occurred when the stomach had emptied more than 80% of its contents and after hunger had increased. Our data are compatible with the hypothesis that the return of hunger is directly related to a decline in the exposure of the upper small intestine to nutrient stimuli, but could be modulated by gastric distension.