The Effect of Protein and Exercise at Different Ages on the Basal Metabolism

Abstract

The basal metabolism of rats 7 to 8 months of age was studied and compared with the total metabolism of these same animals and also with the basal metabolism of other rats 700 days of age. In the investigation involving the younger animals, the effects on metabolism of the proteins of whole milk and whole egg fed at a high and low level and of exercise were observed. With the older rats, the influence of the level of protein intake, exercise and no exercise, was studied on the length of life of the animal. In the study involving the younger rats, the basal heat production was the lowest on the average in the low protein group, somewhat higher in the high protein group and highest in the high protein group that was being exercised. The difference in heat production between any two groups in not great except in the case of the low protein group and the high protein group receiving exercise, in which case the difference is quite significant. The supermetabolism, or the difference between the total metabolism and the basal metabolism, was 26%. With the old rats, a high protein intake was associated with a higher basal metabolism. In comparisons between animals of equal weights, a higher basal metabolism was found in the older animals.