Comparison of bioelectrical impedance and BMI in predicting obesity-related medical conditions.

OBJECTIVE

To determine the relative validity of specific bioelectrical impedance analysis (BIA) prediction equations and BMI as predictors of physiologically relevant general adiposity.

RESEARCH METHODS AND PROCEDURES: Subjects were >12,000 men and women from the Third National Health and Nutrition Examination Survey population. We examined the correlations between BMI and percentage body fat based on 51 different predictive equations, blood pressure, and blood levels of glucose, high-density lipoprotein cholesterol, and triglycerides, which are known to reflect adiposity, while controlling for other determinants of these physiological measures.

RESULTS

BMI consistently had one of the highest correlations across biological markers, and no BIA-based measure was superior. Percent body fat estimated from BIA was minimally predictive of the physiological markers independent of BMI.

DISCUSSION: These results suggest that BIA is not superior to BMI as a predictor of overall adiposity in a general population.