| Abstract: | Objectives : Although BMI (kilograms per meter squared) is widely used as a surrogate measure of adiposity, it is moderately associated (r ～ 0.3) with height among children. We examined whether the resulting preferential classification of taller children as overweight, based on a BMI ≥95th percentile, is appropriate. Research Methods and Procedures : We assessed the cross‐sectional relation of height among 5‐ to 18‐year‐old subjects (n = 1180) to levels of BMI, the sum of 10 skinfold thicknesses, and percentage body fat as determined by DXA. Results : The prevalence of a BMI level ≥95th percentile was substantially higher among 5‐ to 11‐year‐old subjects who were relatively tall for their age than among shorter children. Among 5‐ to 8‐year‐old boys, for example, each SD increase in height‐for‐age was associated with a 4.6‐fold increase in the prevalence of overweight (p < 0.001). Height not only was associated with BMI but also showed similar correlations with the skinfold sum and with percentage body fat; furthermore, the magnitudes of these associations decreased with age. We also found that the association between percentage body fat and BMI (r = 0.85 to 0.90) was close to the maximum correlation that can be achieved by any weight‐height index. Discussion : The use of BMI, which preferentially classifies taller young children as overweight, is appropriate because height and adiposity are correlated before the age of 12 years. |
