Objectives To evaluate performance of anthropometric steps relative to percentage body fat (%BF) measured by dual-energy X-ray absorptiometry (DXA) in children. (of ~0.75-0.90 kappa of ~0.60-0.75 and AUC of ~0.87-0.98; of 0.91 and 0.86 vs. 0.79 kappa of 0.75 and 0.71 vs. 0.59 and AUC of 0.97 and 0.97 vs. 0.91; value of TSF score was higher than those from BMI. In girls TSF also provided a higher agreement than BMI but EPLG1 was only statistically higher for kappa. Conclusions High agreement and small racial-ethnic variations in the association between percentage body fat and anthropometric steps support the use of AR7 anthropometric steps especially waist-to-height ratio and triceps skinfold thickness as proxy indicators for adiposity. scores for %BF and BMI WC waist-to-height AR7 ratio (WHtR) and TSF; and 2) compared the performance of these anthropometric steps for screening high %BF (≥ 75th percentile). Understanding the performance of different anthropometric steps and related potential differences by age sex and race-ethnicity AR7 would help to identify valid anthropometric steps as indicators of obesity and to evaluate the need for racial-ethnic-specific anthropometric recommendations if they are based on measured adiposity. Using anthropometric steps to timely and correctly identify at risk children in clinics or populace surveys for appropriate intervention would help to lessen burdens of obesity and related disorders. METHODS AND PROCEDURES Study populace We used data from 5 355 children aged from 8 to 19 y enrolled in the 2001-2004 National Health and Nutrition Surveys (NHANES) and with measured excess fat mass weight height WC and TSF. NHANES is usually a nationally representative multiethnic sample of the US civilian and included a household interview followed by a standardized physical examination and laboratory assessment (18). We restricted our analysis to the NHANES 2001-2004 data because 1 DXA measured excess fat mass data were only available in NHANES 1999-2004 and 2) DXA data for NHANES 1999-2000 were not available in the public domain name for 8-17-y-old AR7 girls (18). Key study variables Body fat and high %BF Body fat was estimated by whole-body DXA scans (Hologic QDR 4500A fan-beam densitometer; Discovery software version 12.1) administered to participants 8 years of age and older excluding pregnant females and participants who reported taking assessments with radiographic contrast material in the preceding 72 hours who had participated in nuclear medicine studies in the previous 3 days or who had a self-reported weight or height over the DXA table limit such as weight > 300 pounds or 136 kg; height > 6’5” or 196 cm AR7 (18). DXA is considered a quick accurate precise low-risk approach to assess body composition and is often used as a gold standard method in field studies (5 6 In our analysis we focused on %BF; high %BF was defined based on the age- and sex-specific %BF being ≥ 75th percentile for this populace. The 75th percentile of %BF in 2001- 2004 was equivalent to a %BF of 26-33% in males and 36-38% in girls (Table 1). Population-specific percentiles of %BF has been used by other authors (13 14 because there is no agreement about pediatric body fat cut points (7). We selected not to use excess fat mass (kg) as a study outcome because of the additional complexity in data analysis and interpretation due to its variation by body weight (5). TABLE 1 Age- AR7 and sex-specific 25th 50 and 75th percentiles for percentage body fatand anthropometric steps in 8-19-y-old US children: NHANES 2001-2004was calculated based on weight and height which were measured by trained health workers who followed standardized procedures and used regularly calibrated Seca electronic scales and stadiometers (18). was measured at the uppermost lateral border of the hip crest (ilium) to the nearest mm using steel measuring tape (18). We also used waist-to-height ratio (WHtR = % waist circumference / height) to take into account the variation in height. was measured to the nearest 0.1 mm using a Holtain skinfold caliper (18). TSF represents extremity excess fat depots and is among the most commonly collected skinfold thickness (5). Z-scores and percentiles of %BF and anthropometric steps- We calculated age- and sex-specific (for proportion) and assessments (for mean). Because we did not use imputed data the.