Agreement in Body Fat Estimates Between a Hand-Held Bioelectrical Impedance Analyzer and Skinfold Thicknesses in African American and Caucasian Adolescents

The body mass index (BMI), or the ratio of weight in kilograms to the square of height in meters, is widely used to determine the presence or absence of overweight and obesity in adults (National Institutes of Health, 1998). In children and adolescents, a BMI between the 85th and 95th percentiles for age and gender is defined as at risk for overweight, whereas a BMI above the 95th percentile for age and gender is defined as overweight (American Academy of Pediatrics, 2003). Over the past two decades, the prevalence of at risk for overweight and overweight youth has nearly doubled in the U.S. (Ogden, Flegal, Carroll, & Johnson, 2002). Some policy statements (American Academy of Pediatrics, 2003) consider overweight to be synonymous with obesity. However, obesity is an excess of body fat, and obesity in youth has been linked with an increased risk of Type 2 diabetes (Goran, 2001), glucose intolerance, hyperlipidemia (Dietz, 1998), and hypertension (Baskin, Ahluwalia, & Resnicow, 2001). Although many consider BMI an acceptable clinical surrogate of body fatness, it does not differentiate between fat and fat-free tissues. Thus, children and adolescents with the same BMI may differ widely in body fat percentages. For instance, in a sample of 112 adolescent girls, 24 were at risk for an overweight BMI or had an overweight BMI, yet their body fat, as assessed by a four-component body density, total body water, and whole body bone mineral model, ranged from 16 to 42% (Wong, Stuff, Butte, O’Brien-Smith, & Ellis, 2000). In another study of 979 children and adolescents assessed by BMI and the three-component dual-energy x-ray absorptiometry (DXA) model, 90% of girls but only 71% of boys with an overweight BMI also had a DXA-derived body fat percentage above the 95th percentile for age and gender (Ellis, Abrams, & Wong, 1999). Therefore, the presence of either an at risk for overweight BMI or an overweight BMI is no guarantee of excess body fat in an individual child or adolescent (Ellis et al., 1999; Wong et al., 2000). One low-cost alternative to BMI is assessing skinfold thickness to determine body composition in youth. Williams et al. (1992) used the sum of triceps and subscapular skinfold thicknesses to estimate body fat percentage in a sample of 3,320 Caucasian and African American youth ages 5–18 years. They reported that boys with body fat at or above 25% and girls with body fat at or above 30% were two to seven times as likely to have elevated blood pressures and adverse serum lipoprotein levels as those with lower body fat percentages (Williams et al., 1992). These standards, with an adjustment for girls to body fat at or above 32%, have been used for over a decade to identify individuals above the healthy fitness zone in the FITNESSGRAM® health-related test of youth fitness (Meredith & Welk, 2005). However, there are several limitations related to using skinfold Agreement in Body Fat Estimates Between a Hand-Held Bioelectrical Impedance Analyzer and Skinfold Thicknesses in African American and Caucasian Adolescents