Evidence that body size does not determine voluntary food intake in the rat

Rats, 5.5 wk of age, were food restricted for a period of 30 days duration. On termination of caloric deprivation, the food-restricted rats were 142 g lighter than comparable freely eating control rats (177 +/- 3 g vs. 319 +/- 4 g; P less than 0.001). Because of the smaller body size, adipocyte diameter in epididymal pads of the calorie-deprived rats was 52 +/- 1 micron compared to a value of 72 +/- 3 micron for the control rats (P less than 0.001). After restoration of ad libitum feeding, the food-restricted rats experienced an accelerated rate of weight gain until body weight and adipocyte diameter approached those of the control animals. The greater rate of weight gain occurred despite the fact that voluntary food intake remained essentially the same for both groups of animals. Food intake over the 18-wk-long restoration period totaled 3,078 +/- 40 g for the food-restricted rats compared to a value of 3,108 +/- 53 g for the control rats. These results demonstrate that neither body size nor the size of the adipocyte determines voluntary food intake in the rat.