Short-term variations in diet composition change the pattern of spontaneous motor activity in rats.

The nocturnal activity patterns of rats changed significantly within 3 days after they were given unrestricted access to isocaloric diets in which the ratio of carbohydrate to protein was systematically varied. As the ratio increased, the rats were more continuously active. The subjects showed similar responses to variations in this ratio whether the diet contained 15 or 45 percent fat. No correlation was found between the number of calories an animal ate and its activity pattern.