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：当前已存在多种体成分评估方法，但各方法所得结果存在差异。本研究旨在以年轻健康受试者队列作为研究对象，量化不同方法间的结果差异程度。本研究提出假说：不同方法测得的体成分结果差异程度足以导致受试者被错误划分至不同营养分类中。 研究方法与步骤：本研究采用水下称重法（UWW）、生物电阻抗分析法（BIA）、人体测量法（ANT）以及双能X射线吸收测定法（DXA）开展体成分评估。以双能X射线吸收测定法（DXA）为参照，对大量人体测量法（ANT）回归方程（或方程组合）的准确性与精密度进行分析。 结果：以DXA测得的体脂（BF）值为参照时，水下称重法（UWW）在男女两性中均高估了体脂（BF）水平。与之相反，采用特定生物阻抗分析仪测得的生物电阻抗分析法（BIA）在女性群体中低估了体脂（BF），但在男性群体中其测得的体脂与DXA结果无显著差异。多组人体测量法（ANT）回归方程的体脂估算值存在显著差异：当女性DXA测得体脂为25.5%、男性为13.9%时，女性的体脂估算差值范围为8%~29%，男性为6%~29%。但若选用准确性与精密度综合最优的回归方程，人体测量法（ANT）的性能并未劣于DXA。 研究结论：本研究为不同方法、以及多组人体测量法（ANT）回归方程下年轻健康受试者体成分结果的对比提供了依据。本研究同时明确了适配本研究队列的最优人体测量法（ANT）回归方程清单，并报告了这些方程的准确性与精密度。