Obesity is considered a condition presenting a complex, multi-factorial etiology that implies genetic and non-genetic factors. The way the available information should be efficiently and strategically used in the obesity and overweight prohylaxisprogrammes for children all over the world is still unclear for most of the risk factors.

Mothers’ pre-conception weight and weight gain during pregnancy are two of the most important prenatal determinants of childhood obesity. Maternal obesity and gestational weight gain are associated with foetal macrosomia and childhood obesity, and this effect extends into adulthood. Obesity and the metabolic syndrome in children originate in intrauterine life.

The current obesity epidemic is probably the result of our evolutive inheritance associated with the consumption of highly processed food with an increased calorific value. The determination of risk factors involved in child obesity are: genetic predisposition, diet, sedentary behaviors, socioeconomic position, ethnic origin, microbiota, iatrogenic, endocrine diseases, congenital and acquired hypothalamic defects, usage of medications affecting appetite.

However, the vast majority of patients will not have any of these identifiable conditions. Regardless of the aetiology, all the patients should be considered for modifiable lifestyle risk factors and screened for the complications of obesity.