A process is provided for reducing adiposity in an animal such as a companion animal by feeding the animal an effective amount of Vitamin A for a time sufficient to reduce adiposity in the animal. Preferably, the such effective amount comprises from about 50,000 IU to about 1,000,000 IU of Vitamin A per kilogram of diet. Such an effective amount provides sufficient Vitamin A to decrease accumulation of body fat, increase UCP1 levels, and decrease serum leptin levels in the animal.