[An overview of diseases inducing secondary obesity]

Obesity is a heterogeneous syndrome. The pathophysiology of obesity seems to be simple because of a chronic excess of nutrient intake relative to the low level of energy expenditure. However, several pathogenic processes are involved in the development of obesity. Moreover, there are primary diseases that cause secondary obesity, also called symptomatic obesity, in process of those clinical explorations. The symptomatic obesity is classified as endocrine, central nervous-related, congenital and drug-induced obesity. Since simple obesity is diagnosed after excluding symptomatic obesity, we should understand pathophysiology and clinical characteristics of each of primary diseases that cause obesity.