Supplementary Material for: Direct Comparison of (Anthropometric) Methods for the Assessment of Body Composition

Objective: Several methods for the assessment of body composition exist, yet they yield different results. The present study aimed to assess the extent of these differences on a sample of young, healthy subjects. We hypothesised that differences in body composition results obtained with different methods will vary to the extent that a subject can be misclassified into different nutritional categories. Research Methods and Procedures: Underwater weighing (UWW), bioelectrical impedance analysis (BIA), anthropometry (ANT), and dual-energy X-ray absorptiometry (DXA) were used to assess body composition. An extensive list of ANT regression equations (or sets of equations) was analysed in terms of accuracy and precision relative to DXA. Results: When DXA-determined body fat (BF) values were taken as a reference, UWW overestimated BF in both genders. In contrast, BIA (measured with a given bioimpedance analyser) underestimated BF in females, although BIA-determined BF did not differ from DXA in males. A huge difference in BF estimates (8–29% for females and 6–29% for males, for DXA-determined BF of 25.5% and 13.9% for females in males, respectively) was observed across a number of ANT regression equations; yet, ANT proved not to be inferior to DXA, provided that regression equations with the highest combinations of accuracy and precision were chosen. Conclusions: The study proved grounds for comparison of body composition results of young, healthy subjects, obtained with different methods and across a wide range of ANT regression equations. It also revealed a list of the most appropriate ANT regression equations for the selected sample and reported their accuracy and precision.

研究目的：目前已开发出多种体成分评估方法，但不同方法的测定结果存在显著差异。本研究以健康青年受试者为受试样本，旨在量化评估各方法间的结果差异程度。本研究提出假设：不同方法所测得的体成分结果差异幅度，足以导致受试者被错误归类至不同营养类别中。研究方法与流程：本研究采用水下称重法（Underwater Weighing, UWW）、生物电阻抗分析法（Bioelectrical Impedance Analysis, BIA）、人体测量法（Anthropometry, ANT）及双能X线吸收测定法（Dual-energy X-ray Absorptiometry, DXA）开展体成分评估。针对涵盖范围广泛的人体测量法回归方程（或方程组合），本研究以DXA为金标准，分析其测定结果的准确性与精密度。研究结果：以DXA测定的体脂（Body Fat, BF）值为参照标准时，水下称重法对两性的体脂均存在高估情况。与之相对，采用特定生物阻抗分析仪测得的BIA结果在女性群体中表现为体脂低估，但在男性群体中，BIA测定的体脂结果与DXA无显著差异。在多款人体测量法回归方程中，体脂估算值存在显著差异：当女性受试者DXA测得体脂率为25.5%、男性为13.9%时，女性体脂估算差值范围为8%~29%，男性为6%~29%；但若选取准确性与精密度综合最优的回归方程，人体测量法的测定表现并不劣于DXA。研究结论：本研究为不同方法及多款人体测量法回归方程下的健康青年受试者体成分结果对比提供了实证依据。本研究同时明确了适配本次受试样本的最优人体测量法回归方程清单，并报告了各方程的准确性与精密度指标。