Assessment of total body fat percentage from regional spine and femur DXA measurements among Chinese women and men.

This study was aimed at determining the correlation between regional body composition and total body fat percentage (TBF%), as measured by dual-energy X-ray absorptiometry (DXA), among Chinese women and men. Men (n=203) and women (n=630), aged 20-87yr, were assessed for height, weight, and body mass index (BMI) and for total body, lumbar spine (L2-L4), and left and right proximal femur fat percentage using DXA. Based on their BMI, male and female subjects were subdivided into 4 groups. For all groups, the TBF% derived from the total body scan was strongly correlated with spine %fat (r range: 0.60-0.96) and the left and right femur %fat (r range: 0.72-0.80 and 0.69-0.83, respectively), as obtained from regional scans. In stepwise regression, TBF% was best assessed by spine %fat, left femur %fat, age, and BMI for both genders (male: R(2)=0.88; female: R(2)=0.84). Equations with spine %fat, age, and BMI also provided good estimates of TBF% (male: R(2)=0.80; female: R(2)=0.75), whereas android and gynoid %fat were predicted with spine %fat and left femur %fat, respectively, and the predicted fat percentage ratio of android to gynoid (A/G) could be obtained from spine %fat and left femur %fat. The cross-validation results showed that the accuracy of all prediction equations was high in the male group, whereas prediction equations with high-to-moderate accuracy were found in the female group. Therefore, for DXA systems that do not offer total body scan, clinicians can assess TBF% using data obtained from regional scans.