Xenin is a gastrointestinal hormone reported to supress food intake. Little is known about the role of xenin in body weight regulation. I hypothesized that enhanced xenin action will cause alterations in lipid metabolism towards reducing adiposity and body weight. To address this hypothesis, the present study investigated the effect of intracerebroventricular (i.c.v.) xenin treatment on body weight and lipid metabolism in obese mice. Effects of xenin on lipid metabolism were also investigated ex vivo in cultured gonadal white adipose tissue (WAT) and 3T3-L1 adipocytes. I.c.v. xenin treatment reduced body weight gain and increased phosphorylation of hormone sensitive lipase (HSL) in WAT of obese mice. Xenin treatment increased glycerol, free fatty acid (FFA) release and phosphorylation of HSL ex vivo in cultured WAT and 3T3-L1 adipocytes. These findings suggest that enhanced xenin action may be beneficial in reversing obesity by increasing the use of stored fats for fuel.