Accuracy Of Body Fat Estimation Using 3d Whole Body Optical Scan Compared To Circumference-based Methods

BACKGROUND: Circumference-based equations (CBE) are used to estimate body fat (%BF), but the accuracy of those estimates is dependent on human error. A newer technique, 3-dimensional whole body optical imaging (3D), may improve accuracy of %BF assessment by reducing the human error inherent with currently accepted population-based CBE methodology. The accuracy of 3D for estimating %BF has not been studied in reference to CBE. PURPOSE: To compare %BF estimate by 3D and associated %BF model to CBE using computerized circumference measurements. METHODS: Study population was a diverse cohort of 1,707 Soldiers (1,171 men; 536 women). Two methods were used to assess % BF: 1) 3D, which used computerized body circumference measurements based on anatomical landmarks from four sites: abdomen, bicep, thigh, and calf and estimated %BF using 3D-associated software, and a 2) CBE which estimated %BF based on circumferences of two sites (neck and abdomen), that were obtained from the 3D scan in the same cohort. The criterion method used to assess accuracy was dual-energy x-ray absorptiometry (DXA). Data was stratified by age and sex for accuracy of %BF by 3D and CBE. Linear models were used to estimate R2 and root mean square error (RMSE) values. Comparative analysis was completed using paired t-tests of the absolute value of the residuals, with statistical significance set at p ≤ 0.05. RESULTS: The 3D equation produced an R2 of 0.68 and a RMSE of 4.25% compared to the 0.55 and 5.02% from the CBE equation. Model predictions from the 3D and CBE equations were different based on residuals from DXA output of %BF (p < 0.001). %BF by 3D was more accurate in predicting %BF than CBE for men across all ages, and for women greater than age 27 (p < 0.001 and p = 0.044, respectively). CONCLUSIONS: 3D methods provide a potential advancement to %BF assessment. The current 3D method introduces a less invasive and more accurate assessment of % BF compared to traditional CBE methods.