Inhibition of lipid accumulation and enhancement of energy expenditure by the addition of pyruvate and dihydroxyacetone to a rat diet.

To assess the effects of oral intake of pyruvate and dihydroxyacetone on body composition and metabolism, rats were divided into two groups and pair-fed one of the following isocaloric diets for 112 days. The control diet was a liquid diet with the following caloric composition: 14% protein, 28% fat, and 58% carbohydrate. The experimental diet was the same as the control diet except for the partial substitution of carbohydrate content with pyruvate and dihydroxyacetone. Rats receiving the experimental diet gained less weight than rats receiving the control diet. This reduction in body weight appeared to be largely the result of inhibition of lipid accumulation. The experimental diet reduced body fat content by 32% without any significant effect on either protein or water content. Rats receiving the experimental diet did not have increased loss of calories in the stool, but had greater rates of heat production and energy expenditure, which was accompanied by an elevated plasma level of thyroxine. Furthermore, rats receiving the experimental diet had a smaller rate of lipid synthesis in their adipose tissue, and a reduced plasma insulin level. The data suggest that inhibition of gain in weight with the addition of pyruvate and dihydroxyacetone to the diet is the result of an increased loss of calories as heat at the expense of storage as lipid.