Long-and short-term regulation of feeding patterns in the rat.

Analysis of feeding patterns in rats showed that the amount of food eaten in relatively long intervals (24-72 hr) was correlated with mean meal size and was essentially uncorrelated with meal frequency. Similarly, the regulatory adjustment in daily food intake occurring in response to changes in environmental temperature was shown to be the result of an adjustment in mean meal size, with no change in meal frequency. On the other hand, the amount of food eaten in relatively short intervals (3-12 hr) was shown to be more highly correlated with meal frequency than with mean meal size, and a reliable correlation between meal size and the postmeal interval was obtained. It was also shown that the meal size/postmeal interval regression equation predicts the long-term relation between mean meal size and the amount of food eaten. Take together, these results indicate that meal frequency is controlled largely by short-term regulatory signals and that at least some long-term regulatory signals affect meal size directly.