Takase S, Morimoto A, Moriuchi S, Hosoya N
J Nutr Sci Vitaminol (Tokyo) 1981;27(3):219-229

This study was conducted to investigate the effects of various proportions of dietary carbohydrate and fat in diet on protein and carbohydrate metabolism. The growth rate, nitrogen balance, urinary and serum urea levels, and the activities of key ureogenic and gluconeogenic enzymes in the livers were examined in the weanling and growing rats. The rats were raised on a 20% casein diet containing various proportions of carbohydrate and fat, viz. 30% and 50%, 50% and 30%, 60% and 20% or 70% and 10% as calorie percent, respectively, for 10 days. For both weanling and growing rats, the growth rate was unaffected by the alteration in the proportions of carbohydrate and fat in the diets. However, in the rats fed on the 30% carbohydrate-50% fat diet, the urinary excretion of nitrogen and urea were reduced in both groups and these findings were reflected in the reduced serum urea level. Arginase activity decreased. In contrast, glucose-6-phosphatase activity was enhanced in the animals of the 30% carbohydrate-50% fat diet group as compared to the other groups. These results suggest that a low carbohydrate-high fat diet causes the reduction of urea formation and the enhancement of glucose formation at a fixed level of protein in the diets in weanling as well as in growing rats.