Ractopamine is a small compound that binds to beta-adrenergic receptors in the body. It takes energy from fat growth and redirects it to promote the increase of muscle fiber diameter and the growth of lean muscle protein in the ham, belly, and shoulder. Ractopamine has been shown to increase hot carcass weight, dressing percent and loin eye area in pigs, and can also reduce the number of days to market. The growth response is observed in many species, but ractopamine has only been officially approved for use in swine.