Issues relating to normalization of body fat content in men and women.
Issues relating to normalization of body fat content in men and women.
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发表时间：
1995-09
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通讯作者：
M. Goran;D. B. Allison;E. Poehlman
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作者：
M. Goran;D. B. Allison;E. Poehlman
目的：体重指数（BMI）、体脂百分比和脂瘦比是常用的肥胖指标。比值基于分子（例如脂肪量）和分母（例如体重）之间的回归具有零截距的假设。如配套文件中所示，非零截距导致几个问题时，比率用于调整数据和协方差分析（ANCOVA）往往是首选的统计工具。本文的目的是检查是否BMI，%体脂和脂肪：瘦肉比例符合必要的标准，适当的肥胖指数使用性别比较为例。结果在720名健康男性和女性中，男性BMI高于女性，（24.9 +/- 3.3 vs 23.4 +/- 3.2 kg/m2，P < 0.001），但女性的脂肪量、%脂肪和脂肪/瘦肉比更高（14.8 +/- 8.4 vs 19.1 +/- 8.1 kg脂肪; 18.6 +/- 8.7 vs 29.9 +/- 9.7%体脂; 0.24 +/- 0.14 vs 0.46 +/- 0.20脂肪：瘦肉比; P < 0.001）。男性（r = 0.40）和女性（r = 0.36）的体重（BM）与身高2相关，回归斜率相等（女性为17.1 +/- 1.9 vs 15.6 +/- 2.3 kg/m2），但截距与零不同（男性为24.1 kg，女性为20.7 kg）。当使用ANCOVA对身高2进行BM调整时，男性仍然明显比女性重（74.4 +/- 11.0 vs 68.8 +/- 11.6 kg; P < 0.001）。男性的脂肪量（FM）与BM显著相关（r = 0.64）和女性（r = 0.78），但回归斜率不同（0.49 +/- 0.03 vs 0.71 +/- 0.03 kg脂肪/kg体重，女性; P < 0.05），截距与零不同（雄性-23.2 +/- 2.2 kg;雌性-24.8 +/- 2.1 kg）。经BM校正的FM在女性中显著更高（11.7 vs 25.6 kg）。在男性中，FM与去脂体重（FFM）呈负相关（r = -0.17）和女性（r = -0.20），回归斜率相似（女性中每千克FFM-0.16 +/- 0.05 vs -0.26 +/- 0.08 kg FM），截距与零有显著差异（雄性24.8 +/- 3.0 kg;雌性30.7 +/- 3.6 kg）。当根据FFM调整FM时，男性（16.3 kg）和女性（17.0 kg）之间没有显著差异。结论：（a）显著截距的存在不支持使用比率作为肥胖指数，应考虑基于回归的模型;（B）男性和女性之间肥胖指数差异的方向和幅度随不同的标准化方法而变化。
OBJECTIVE Body mass index (BMI), % body fat, and the fat:lean ratio are ratios frequently used as obesity indices. Ratios are based on an assumption that the regression between the numerator (e.g. fat mass) and the denominator (e.g. body mass) has a zero-intercept. As shown in the companion paper, non-zero intercepts cause several problems when ratios are used to adjust data and analysis of covariance (ANCOVA) is frequently the preferred statistical tool. The purpose of this paper is to examine whether BMI, % body fat and the fat:lean ratio meet the necessary criteria for suitable obesity indices using gender comparisons as an example. RESULTS In 720 healthy men and women, BMI was higher in men (24.9 +/- 3.3 vs 23.4 +/- 3.2 kg/m2, P < 0.001), but fat mass, % fat and the fat:lean ratio were higher in women (14.8 +/- 8.4 vs 19.1 +/- 8.1 kg fat; 18.6 +/- 8.7 vs 29.9 +/- 9.7% body fat; 0.24 +/- 0.14 vs 0.46 +/- 0.20 for the fat:lean ratio; P < 0.001). Body mass (BM) was correlated with height2 in men (r = 0.40) and women (r = 0.36) with equivalent regression slopes (17.1 +/- 1.9 vs 15.6 +/- 2.3 kg per m2 in women), but the intercepts were different from zero (24.1 kg in men, 20.7 kg in women). When BM was adjusted for height2 using ANCOVA, men remained significantly heavier than women (74.4 +/- 11.0 vs 68.8 +/- 11.6 kg; P < 0.001). Fat mass (FM) was significantly correlated with BM in males (r = 0.64) and females (r = 0.78) but the regression slopes were different (0.49 +/- 0.03 vs 0.71 +/- 0.03 kg of fat per kg body mass in females; P < 0.05) and the intercepts were different from zero (-23.2 +/- 2.2 kg in males; -24.8 +/- 2.1 kg in females). FM adjusted for BM was significantly higher in women (11.7 vs 25.6 kg). FM was inversely correlated with fat free mass (FFM) in males (r = -0.17) and females (r = -0.20), with similar regression slopes (-0.16 +/- 0.05 vs -0.26 +/- 0.08 kg of FM per kg of FFM in women) and the intercepts were significantly different from zero (24.8 +/- 3.0 kg in males; 30.7 +/- 3.6 kg in females). When FM was adjusted for FFM, there was no significant difference between men (16.3 kg) and women (17.0 kg). CONCLUSIONS It is concluded that: (a) the presence of significant intercepts does not support the use of ratios as obesity indices and regression based models should be considered; and, (b) the direction and magnitude of the difference in obesity index between men and women changes with different normalization approaches.