CALORIE INTAKES IN RELATION TO THE QUANTITY AND QUALITY OF PROTEIN IN THE DIET

Abstract

Young male rats were fed 25 diets in which the quantity and quality of protein were varied for a 4-wk. period. Analysis of the data upon food intake and body wts. suggests that the mean daily calorie intake varied as the mean body wt. raised to the 0.88 power. Animals receiving the same diet, but which varied in rate of gain in calorie intake because of inherent differences in the rats themselves, showed a similar relation between food intake and body wt. Published results by Brody indicate that the basal or resting metabolism of rats of this size also varies with body wt. raised a power near this value (0.84-0.9). It therefore appears that the mean calorie intake was a constant percentage about the mean basal metabolic rate during the exptl. period, regardless of the rate of gain or the cause of this difference in gain, i.e., inherent differences or differences in the nutritive value of the diet. It is suggested that the food intake of the animals is controlled by some means at a relatively constant % above basal metabolism. If the food thus consumed contains adequate nutrients, the animal grows, increases its basal metabolism, and thus its food intake,upon succeeding days. If the food eaten does not allow growth, or only limited growth, the remaining calories must be consumed, probably in activity. The efficiency of the animal unable to grow is thus markedly diminished even when the calculation is made only upon the calories above those required for basal metabolism.