Being overweight and obese during childhood and adolescence is a growing worldwide problem and is important as most overweight and obese adolescents remain so in adulthood. Such adults are more likely to develop medical problems such as heart disease, diabetes, strokes and also certain cancers. These problems tend to occur earlier with increasing severity of obesity and with an early age of onset.

Being overweight and obese is usually due to an imbalance between the amount of nutrition a child consumes and the amount of energy expended, on the background of a genetic (an inbuilt) predisposition. There is no easy treatment to reduce a child's weight, and requires a combination of improved eating habits and increased exercise levels. However this is extremely difficult to maintain over a number of years. Very occasionally medication is used if complications such as diabetes develop. Rarely, being overweight or obese can be due to a hormonal imbalance, and this requires careful assessment and treatment.