Lee Gyeongsil, Choi Seulggie, Park Sang Min
Department of Family Medicine, Seoul National University Hospital, Seoul 03080, Korea.
Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea.
Nutr Res Pract. 2021 Oct;15(5):604-612. doi: 10.4162/nrp.2021.15.5.604. Epub 2020 Dec 18.
BACKGROUND/OBJECTIVES: We aimed to investigate the association of waist circumference (WC) with body composition among individuals with a normal body mass index (BMI) to distinguish muscle and fat mass, as both affect health differently.
SUBJECTS/METHODS: We analyzed dual-energy X-ray absorptiometry data (derived from the Korean National Health and Nutrition Survey, which includes information on fat and lean mass) of 7,493 adults with a normal BMI. Subjects were categorized into four groups of increasing WC. The fourth group was defined as being centrally obese. Each number of subjects are as follows: 1,870, 695, 231, and 39 among men and 3,054, 1,100, 406, and 98 among women. We conducted a sex-stratified linear regression analysis of body composition according to WC group after adjustments for covariates.
We observed a positive association of body fat with increasing WC in both men and women (all for trend: < 0.001). The adjusted mean values for percent body fat with 95% confidence intervals (CIs) according to the four WC groups in ascending order were 17.8 (17.5-18.3), 21.0 (20.6-21.5), 22.1 (21.5-22.8), and 25.1 (24.2-26.1) in men and 29.7 (29.4-30.0), 32.0 (31.6-32.3), 32.9 (32.4-33.4), and 34.7 (33.2-36.1) in women. However, there was an inverted J-shaped association between muscle mass and WC. The fourth group had a higher percent body fat and lower muscle mass than other groups. The adjusted mean values for appendicular skeletal muscle mass index (kg/m) with 95% CIs according to the four WC groups in ascending order were 7.55 (7.51-7.59), 7.62 (7.56-7.68), 7.65 (7.56-7.74), and 7.22 (7.04-7.41) in men and 5.83 (5.80-5.85), 5.96 (5.92-6.00), 6.03 (5.96-6.10), and 5.88 (5.73-6.03).
There was a positive association between body fat and WC among individuals with normal BMI; conversely there was an inverted J-shaped association between lean body mass and WC. Our findings support the WC measurement should be included in obesity evaluations for adults with a normal BMI.
背景/目的：我们旨在调查正常体重指数（BMI）个体的腰围（WC）与身体成分之间的关联，以区分肌肉量和脂肪量，因为二者对健康的影响不同。
对象/方法：我们分析了7493名BMI正常的成年人的双能X线吸收法数据（源自韩国国家健康与营养调查，其中包含脂肪和瘦体重信息）。受试者按WC递增分为四组。第四组被定义为中心性肥胖。每组男性受试者人数如下：1870、695、231和39；女性受试者人数如下：3054、1100、406和98。在对协变量进行调整后，我们按WC组对身体成分进行了性别分层线性回归分析。
我们观察到男性和女性的体脂均与WC增加呈正相关（所有趋势P值均<0.001）。按四个WC组升序排列，男性体脂百分比的调整后均值及其95%置信区间（CI）分别为17.8（17.5 - 18.3）、21.0（20.6 - 21.5）、22.1（21.5 - 22.8）和25.1（24.2 - 26.1）；女性分别为29.7（29.4 - 30.0）、32.0（31.6 - 32.3）、32.9（32.4 - 33.4）和34.7（33.2 - 36.1）。然而，肌肉量与WC之间呈倒J形关联。第四组的体脂百分比高于其他组，肌肉量低于其他组。按四个WC组升序排列，男性四肢骨骼肌质量指数（kg/m）的调整后均值及其95%CI分别为7.55（7.51 - 7.59）、7.62（7.56 - 7.68）、7.65（7.56 - 7.74）和7.22（7.04 - 7.41）；女性分别为5.83（5.80 - 5.85）、5.96（5.92 - 6.00）、6.03（5.96 - 6.10）和5.88（5.73 - 6.03）。
正常BMI个体的体脂与WC之间呈正相关；相反，瘦体重与WC之间呈倒J形关联。我们的研究结果支持在对BMI正常的成年人进行肥胖评估时应纳入WC测量。
