Metabolic therapy is a holistic method based on the belief that through a combination of special diets, enzymes, and nutritional supplements, toxic substances in the body may be removed. These toxins are found in the environment and food, and as they build up in the body they lead to chemical imbalances that cause diseases such as cancer and arthritis. Metabolic therapy practitioners believe that if individual cells are supplied with the necessary amounts of essential nutrients and the body is able to eliminate the waste products of cellular metabolism through proper bowel movements, efficient breathing, and normal excretion, then the body may maintain a healthy state. Metabolic therapy provides the treatments necessary to help the body detoxify itself and maintain the correct amount of nutrients.

Although metabolic therapies differ greatly among practitioners, they are all based on special diets that include natural foods, vitamins, and mineral supplements, as well as detoxification and stress-reduction exercises. The main goal of all kinds of metabolic therapy is to reinforce the body's immune system and to restore it to a fully functional condition in order to eliminate cancer cells and prevent disease. The most common types of metabolic therapy are Gerson Therapy, Kelley's treatment, and the Gonzalez treatment. Gerson therapy includes a strict dietary program, coffee enemas, and mineral or chemical supplements. Kelley's treatment involves dietary supplements, detoxification, a restricted diet, chiropractic adjustments, and prayer. The Gonzalez treatment includes extracts or concentrates from animal and digestive enzymes.