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

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.