Interpellet delay and meal patterns in the rat.

Rats typically eat in short discrete meal periods separated by long intermeal intervals. The present study measured meal patterns and total intake of food and water when the rate of access to food pellets within the meal was reduced by delaying the time between pellet deliveries. In contrast to studies that reduce the caloric density of food, simple interpellet delay produced a marked reduction in meal size at the shorter (32 sec or less) interpellet delays. However, longer delays (up to 128 sec) produced no further change in average meal size. The results suggest that meal size is determined (1) by a positive feedback component with a relatively short decay time probably based on gustatory stimulation from feeding, and (2) by a negative feedback component capable of integrating total intake across delays of up to 1 hour. Increasing the delay between pellets appeared to interfere with the positive feedback component, but not with the negative feedback component.