Obesity (a disease of excessive body fat) in children or adolescents is not measured in the same way as adult obesity. In adults, the Body Mass Index (BMI) is the standard diagnostic tool for measuring mild obesity (BMI 30+), morbid obesity (BMI 40+), and malignant obesity (BMI 50+). However, in order to measure obesity in children or teenagers, a measurement called "percentile of Body Mass Index" is used.

Percentiles of Body Mass Index Used to Measure Child Obesity

The weight status of children and adolescents (aged 12-19) is measured with reference to gender-specific growth charts developed by the Centers for Disease Control (CDC). A BMI-for-age is plotted on these charts and shows a child's BMI in relation to that of other children.

See: Weight Chart For Children (Boys) - Weight Chart For Children (Girls)

When is a Child or Teenager Obese?

The Centers for Disease Control (CDC) prefers not to use the word "obesity" for children, adolescents or teenagers. Instead, they say that obesity in children begins at the 95th percentile, which represents a "severe" level of overweight. The 95th percentile roughly corresponds to the obesity point for adults, which is a BMI of 30. The American Obesity Association also uses the 95th percentile for "obesity". Child weight outside the 95th percentile is associated with raised blood pressure and lipids in older adolescents, and increases risk of disease. It is also used as a criteria in clinical research trials of childhood obesity treatments.

Child Obesity Determined By Individual Examination

Even if a child's weight falls outside the 95th percentile, this is not conclusive proof that he/she is obese. Your child's weight status should be assessed by your doctor on the basis of individual examinations conducted over time. This method is required to allow for growth spurts which may otherwise skew your child's BMI-for-age. Obesity is typically diagnosed in individual children when total body weight exceeds 25 percent fat in boys, or 32 percent fat in girls (Lohman, 1987).