Predicting percent body fat from circumference measurements

All U.S. Navy service members are required to meet percent body fat (%BF) standards as a condition of military service. Naval personnel who exceed standards for %BF can be separated from active duty. Currently, %BF predictions are determined by circumference measurements and a prediction equation (circumference equation = CEQ). In view of the importance these prediction results have for personnel retention, a validation study was undertaken to determine the accuracy of %BF prediction for a population determined to be overfat by the CEQ. The population for the validation study comprised men with 22%BF or greater and women with 30%BF or greater. Values for %BF were determined for 49 men and 50 women by hydrostatic weighing (HW) and circumference measurements at the Naval Submarine Medical Research Laboratory (NSMRL) using a regression equation developed at the Naval Health Research Center (NHRC), San Diego, California. The HW and CEQ values were compared to a superset of the original NHRC population. The correlation coefficients for the NSMRL validation group were lower than those reported in the original NHRC group. The results are attributed to the restricted range of NSMRL data and greater error of prediction at extreme ranges of values. A medical diagnostic model was used to evaluate the sensitivity, specificity, and predictive value of CEQ. It shows that the Navy's current procedures produce a 6.8 to 18% false positive rate for individuals declared as having excess body fat. The data suggest that caution should be utilized when using the CEQ method for individual career decisions.