Abstract
The effects of a restricted diet on protein metabolism were studied in rats made obese by a diet containing 30% fat. Three restricted diets, all containing 5% fat, were a high-protein diet (HPD; 50 % casein), a standard-protein diet (SPD; 25% casein), and a low-protein diet (LPD; 5% casein). The intake of feed was restricted to 5g per day. Two weeks later, every group of rats that had eaten one of the restricted diets lost about 100g in body weight; the level of protein intake made no difference in the weight decrease. The nitrogen balance of the HPD and SPD rats was positive; that of the LPD was strongly negative. The amount of moisture in the carcass in the restricted-diet groups was similar, but there were significant differences in the percentage of lipids and protein. The percentage of protein was the highest and that of lipids was the lowest in the carcasses of HPD rats.
These results suggest that the amount of protein in a restricted diet is important to maintain protein metabolism in obese rats.
