Based on the findings that cholest-4-en-3-one, an intestinal metabolite of cholesterol, has an anti-obesity effect on animals, the structure-effect relationship of its 3-oxo derivatives and related compounds were investigated. Cholesten-3-ones, which possesses an enone structure with a carbonyl group at C3, markedly inhibit body weight gain and body fat accumulation, as well as the levels of serum triglyceride and cholesterol in animals without any clinical abnormalities.