Understanding BMI in Youth

Body Mass Index (BMI) is a measure of weight relative to height. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age. A BMI that is healthy at 19 could signal obesity at 10, which is why doctors plot children on percentile growth charts rather than using fixed adult cutoffs.

Why Percentiles Matter

Percentiles compare the child against the CDC reference population of the same age and sex. The 5th to 85th percentile range is considered healthy weight; 85th–94th is overweight; and 95th and above is obese. Under the 5th percentile is underweight. The goal is typically to remain in the healthy band while following the child's own growth curve.

Next Steps

If a child's BMI percentile falls outside the healthy range, it is not an immediate cause for alarm, but it is a reason to have a conversation with a healthcare provider. They can assess other factors like diet, physical activity, and family history to provide a complete picture of health.