Influence of Calorie Intake on Cancer Risk. Rats were fed diets in which the calorie content was restricted to varying degrees relative to what would have been ingested if food were made freely available in unlimited amounts. The carcinogen dimethybenz(a)anthracene (DMBA) was administered to all animals and breast cancer rates were then measure. Note the dramatic drop in cancer rates observed in animals whose calorie intake was restricted. Reduced cancer incidence after caloric restriction has also been observed for spontaneous tumors. (Based on data from D. Kritchevsky, Toxicological Sci. 52 Suppl. (1999): 13 (Table 4).)