The effect of the metabolite glycerol on food intake and body weight in rats

Abstract

Plasma glycerol levels are correlated with adipose tissue mass and adipose cell size. Glycerol thus has been proposed as a humoral signal reflecting the state of fat storage. Small decrements in body weight and food intake following subcutaneous injections (2–4 daily) of glycerol have been reported. Oral administration of glycerol (1 g/kg/day) but not equicaloric glucose is effective in reducing body weight gain and decreasing food intake in growing male Sprague Dawley rats. Mature obese and lean Zucker male rats are similarly responsive to orally-administered glycerol at either 1 g/kg or 2 g/kg/day. Subcutaneous administration of 160 mg/kg/day of glycerol but not glucose via Alzet Mini-Pumps is also effective in reducing body weight gain and food intake. It thus appears unlikely that decreases in body weight gain or food intake following oral or peripheral glycerol administration are due to caloric or taste factors or to a primary osmotic diuretic effect. The observed glycerol effects in these experiments, however, are small and transient, with recovery beginning within 3–4 days of treatment. One possible interpretation of these data is that the action of exogenously administered glycerol is a function of the ratio of plasma glycerol to some other metabolite(s) which change with weight loss.