The definitions for children and adolescents are less defined when compared to adults and varies by the reference source that is used. While the body mass index formula remains the same, the body mass index is taken into consideration with the age/growth curves for children.
Overweight and obesity for children and adolescents are defined respectively as being at or above the 85th and 95th percentile of Body Mass Index (BMI).
The American Obesity Association, (AOA) uses the 85th percentile as a criterion for being overweight because it corresponds to a body mass index or BMI of 25 in the adult population. The AOA uses the 95th percentile as criteria for obesity because it corresponds to a body mass index or BMI of 30, which is obesity in adults.
Criteria based on the 2000 CDC BMI-for-age-growth charts for the US defined children as overweight if their Body Mass Index (BMI) was at or above the 95th percentile.