How is overweight/obesity diagnosed in adolescents?

• A. BMI plotted on CDC growth charts for children over 2 years
• B. Waist circumference alone
• C. Weight percentile ranking only
• D. Height percentile

Answer: (A)

Diagnosing overweight and obesity in adolescents is done using BMI adjusted for age and sex, interpreted with standardized growth charts. Measure the teen’s height and weight, calculate BMI, and then plot that value on the BMI-for-age percentile chart appropriate for their sex. This method accounts for how body composition changes as kids grow, which simple weight or height comparisons don’t capture.

If the BMI percentile is at or above the 85th but below the 95th, that indicates overweight. If the percentile is at or above the 95th, that indicates obesity. This percentile-based approach is preferred because it reflects relative body mass in relation to peers, rather than relying on a single number like weight or waist size.

Waist circumference alone isn’t used to diagnose overweight or obesity, since it doesn’t define overall excess fat relative to height and age. Height percentile or weight percentile by themselves don’t provide a complete assessment of adiposity, since they don’t account for the child’s age- and sex-specific body mass relative to growth patterns.