children's obesity is the main risk factor for adult obesity, as well as for the metabolic syndrome, type 2 diabetes mellitus and cardiovascular diseases, which reduce life quality and expectancy. the metabolic syndrome is a clinical diagnosis that identifies a population that has high risk of cardiovascular diseases. insulin resistance appears as the common link and the trigger factor of metabolic impairments, modulated by genetic and environmental circumstances. the metabolic syndrome can be found in children, but at present it isn't clearly defined. the international diabetes federation's (idf) criteria for children and adolescents are used the most because of their easy management; waist measurement is its principal component. an international definition is needed to be able to compare different studies, and until this isn't accomplished, it shouldn't be diagnosed in children less than 10 years.