The invention provides methods for one or more of enhancing energy metabolism, promoting healthy energy metabolism, maintaining healthy energy metabolism, preventing conditions that result in a decline or deficiency in energy metabolism, treating conditions that result in a decline or deficiency in energy metabolism, and preventing the accumulation of excess body fat in animals without reducing energy intake by the animals. The methods comprise administering isoflavones to the animals, preferably in amounts of from about 0.001 to about 10 g/kg/day.