Influence of Carbohydrate-to-Fat Ratio on Metabolic Changes Induced in Rats by Feeding Different Carbohydrate-Fat Combinations

Abstract

This study was designed to determine whether changing the relative proportions of carbohydrate and fat in the diet would influence metabolic responses in rats to different sources of the 2 nutrients. Four carbohydrate-fat combinations (glucose and fructose each with corn oil (CO) and with hydrogenated coconut oil (HCO)) were combined in high carbohydrate:low fat and low carbohydrate:high fat diets. Protein and caloric values of all diets were equivalent. Eight groups of male, weanling rats were each fed one of the experimental diets for 2 to 4 weeks. Reducing the carbohydrate-to-fat ratio from 64:5 to 19:25 (by weight) resulted in the following changes in liver functions: 1) marked reduction or complete elimination of responses of the glucose-6-phosphatase and fructose diphosphatase enzyme systems to dietary fructose; 2) significant increase in response of glucose-6-phosphatase to dietary HCO; 3) decreases in liver glycogen, to a different extent with different carbohydrate-fat combinations; 4) striking increases in total lipid in rats fed CO or HCO with glucose; and 5) increases in cholesterol in rats fed CO, and in phospholipid in rats fed HCO.