Body fat percentile curves for U.S. children and adolescents

Abstract

Background: To date, several studies have been published outlining reference percentiles for BMI in children and adolescents. In contrast, there are limited reference data on percent body fat (%BF) in U.S. youth.

Purpose: The purpose of this study was to derive smoothed percentile curves for %BF in a nationally representative sample of U.S. children and adolescents.

Methods: Percent fat was derived from the skinfold thicknesses of those aged 5-18 years from three cross-sectional waves of the National Health and Nutrition Examination Survey (NHANES) IV (1999-2000, 2001-2002, and 2003-2004; N=8269). The LMS (L=skewness, M=median, and S=coefficient of variation) regression method was used to create age- and gender-specific smoothed percentile curves of %BF.

Results: Growth curves are similar between boys and girls until age 9 years. However, whereas %BF peaks for boys at about age 11 years, it continues to increase for girls throughout adolescence. Median %BF at age 18 years is 17.0% and 27.8% for boys and girls, respectively.

Conclusions: Growth charts and LMS values based on a nationally representative sample of U.S. children and adolescents are provided so that future research can identify appropriate cut-off values based on health-related outcomes. These percentiles are based on skinfolds, which are widely available and commonly used. Using %BF instead of BMI may offer additional information in epidemiologic research, fitness assessment, and clinical settings.