BMI for Children and Teens: How to Interpret and Use It
BMI for children and teens is different from adults. It uses age- and sex-specific percentiles to assess weight status and growth patterns.
What is BMI-for-age?
- BMI-for-age compares a child's BMI with others of the same age and sex.
- It is plotted on CDC or WHO growth charts.
- The result is a percentile, not a direct category like adults.
Why Use Percentiles?
- Children grow at different rates.
- Percentiles account for age, sex, and development.
- Helps identify underweight, healthy weight, overweight, and obesity in youth.
BMI Percentile Categories
| Percentile | Weight Status |
|---|---|
| < 5th | Underweight |
| 5th-84th | Healthy weight |
| 85th-94th | Overweight |
| ā„ 95th | Obese |
How to Calculate and Interpret
- Measure height and weight.
- Calculate BMI using the standard formula.
- Find the child's age and sex.
- Plot BMI on a growth chart to find percentile.
- Interpret based on percentile range.
Example
- 10-year-old boy, BMI = 19
- Plot on CDC chart: 85th percentile
- Status: Overweight
Why Growth Charts Matter
- Track growth over time
- Identify early health risks
- Guide nutrition and activity recommendations
Limitations
- Not a diagnostic tool
- Does not measure body fat directly
- Must be interpreted by healthcare professionals
When to Seek Help
- Rapid changes in percentile
- Consistently high or low percentiles
- Concerns about growth or development
Conclusion
BMI-for-age is a valuable screening tool for children and teens, but should always be interpreted in context by healthcare providers.