Excess weight in children and adolescents is typically defined using body mass index (BMI) percentiles adjusted for age and sex:
BMI above the 85th percentile is considered overweight.
BMI above the 95th percentile indicates obesity.
Obesity severity is classified as:
Class I: BMI ≥100% to <120% of the 95th percentile value.
Class II: BMI ≥120% of the 95th percentile value or a BMI ≥35 kg/m².
Class III: BMI ≥140% of the 95th percentile value or a BMI ≥40 kg/m².