Methods for promoting healthy body weight and improving a variety of related physiological factors, including serum serotonin levels, serum leptin levels, fat oxidation, cholesterol levels, and body mass index, in persons or other mammals, include administering to those persons or other mammals effective amounts of hydroxycitric acid or a combination of hydroxycitric acid, chromium and gymnemic acid, which work synergistically to further to promote healthy body weight and improve these physiological factors.