Most obese individuals, both children and adults, have an increase in lean weight (LBM) as well as fat, the former accounting for as much as 40 percent of the excess weight in some studies. Intentional overfeeding of normal individuals augments LBM as well as fat. Human obesity thus differs from some types of experimental and hereditary obesity in animals, since these are associated with a decreased LBM. Exceptions are those individuals with Cushing's syndrome.