Abstract: The additive according to the present invention contains the fruit juice of a prickly pear cactus. The prickly pear cactus fruit juice contains rich vitamins, minerals, soluble dietary fiber, pectin, etc. Thus, the additive prevents increase of body weight even when the amount of food being taken is increased. The rich soluble fiber included in the prickly pear cactus fruit juice shortens the intestinal retention time of food, thereby regulating the functions of the intestines, preventing obese. The additive reduces the adipose tissue weight without increasing organ weight. The additive also reduces serum lipids by the pectin included in the cactus fruit juice.