Children are usually considered overweight if their body mass index is between the 85th and 97th centile. These children also look fat. A child is not considered overweight if the weight for age is above the 97th centile but the body mass index is normal. These children are simply big for their age.
The definition of overweight remains very controversial and a number of different definitions are used. Overweight (which refers to the BMI) must not be confused with overweight-for-age.