Anthropometric predictors of visceral adiposity in normal-weight and obese adolescents.

BACKGROUND: Obesity and fat distribution patterns [subcutaneous vs. visceral adipose tissue (VAT)] are important predictors of future cardiometabolic risk. As accurate VAT measurement entails imaging, surrogate anthropometric measurements that would be cheaper and quicker to obtain would be highly desirable. Sagittal abdominal diameter (SAD) may be better than other VAT surrogate measures in adults, but the value of SAD to predict magnetic resonance imaging (MRI)-determined VAT in adolescents of different races, sexes, and pubertal stages has not been determined. AIM: To test the hypothesis that SAD correlates more strongly with volumetric VAT than other anthropometric measurements, independent of age, sex, race, and Tanner stage. SUBJECTS AND METHODS: Twenty-eight normal-weight and 44 obese adolescents underwent Tanner staging, anthropometric examinations, and abdominal MRI for volumetric partitioned fat calculation.
RESULTS: VAT increased exponentially in the body mass index (BMI) > 97th percentile range. SAD, waist circumference (WC), BMI, and BMI Z-score correlated strongly with VAT (correlation coefficients of 0.85-0.86, all p-values < 0.0005); waist-hip ratio was less predictive of VAT (r = 0.68, p < 0.0005). On hierarchical regression, the strongest predictors of VAT in obese subjects were BMI Z-score and SAD (R(2)  = 0.34 vs. 0.31, respectively, p < 0.0005); in normal-weight subjects, most anthropometric measures predicted VAT equally (R(2)  = 0.16-0.18, p-values = 0.018-0.026).
CONCLUSIONS: Unlike adults, in obese adolescents, SAD is not the strongest predictor of visceral adiposity. BMI Z-score is equivalently predictive and, together with BMI, provides sufficient information to assess visceral adiposity; more specialized anthropometric measurements (e.g., SAD and WC) do not add additional predictive value.