ICV beta-hydroxybutyrate: effects on food intake, body composition, and body weight in rats.

This study examined the effect of long-term intracerebroventricular (ICV) infusion of beta-hydroxybutyrate (beta HB) on food intake, diet selection, body weight, and body composition in rats. Female rats were divided into 2 groups and implanted with a 28-day osmotic pump connected to a lateral cerebroventricular cannula. One group was infused with artificial cerebrospinal fluid (aCSF) and the other with beta HB for 28 days. The rats had free access to both a high-fat/low-carbohydrate and a low-fat/high-carbohydrate diet (isocaloric) for the 28-day infusion period. The group infused with beta HB had a significantly lower body weight gain during the infusion period. Cumulative food intake increased in the same manner in both groups. Fat pad weights and carcass lipid content were significantly higher in beta HB rats, despite the equivalent caloric intake in both groups and the decreased body weight. Our observations are in accord with earlier studies indicating that beta HB infused ICV reduces body weight, but not necessarily food intake. Increased adiposity in association with decreased body weight change in beta HB-infused rats strongly suggests that energy is being partitioned to fat deposition at the expense of lean tissue growth when ketone bodies are infused into the cerebroventricles.