Hiraiwa Eri, Yamamoto-Wada Risako, Deguchi Kanako, Ushiroda Chihiro, Naruse Hiroyuki, Iizuka Katsumi
Department of Clinical Nutrition, Fujita Health University, Toyoake 470-1192, Japan.
Faculty of Medicine, Fujita Health University, Toyoake 470-1192, Japan.
Nutrients. 2025 May 23;17(11):1766. doi: 10.3390/nu17111766.
Skeletal muscle mass index (SMI) and body fat percentage (BF%) are components of body mass index (BMI) but are considered to play independent roles. We aimed to clarify whether SMI and BF% are associated with nutritional markers independent of BMI in underweight women. This retrospective observational study included a total of 102 women aged 20-65 years who were referred to the outpatient nutrition evaluation clinic from 2022 to 2024 with a body mass index (BMI) < 17.5. We performed a multivariate analysis with SMI and BF% as independent variables and BMI, BMI ratio (present-to-age 20 ratio), grip strength, and biochemical nutritional indicators (vitamin B level (ng/mL), cholesterol level (mg/dL), lymphocyte count (/μL), and HbA1c (%) level) as dependent variables, adjusting for age. Women aged 30.9 ± 10.2 years (yo) with a BMI of 17.0 ± 0.7 participated in this study. BMI (kg/m) was positively associated with SMI (kg/m) (β (95% CI): 1.6 [1.4, 1.9], < 0.001) and BF% (0.2 [0.1, 0.2], < 0.001), and the BMI ratio (present-to-age 20 ratio) was positively associated only with BF% (0.5 [0.05, 0.9], = 0.03). Grip strength was positively associated with SMI (4.0 [1.4, 6.6], = 0.003), and lymphocyte count was positively associated with BF% (β (36.2 [6.0, 66.5], = 0.02). BMI was not associated with grip strength or lymphocyte count. Vitamin B, cholesterol, and HbA1c were not associated with SMI, BF%, or BMI. These results indicate that SMI reflects BMI and grip strength, whereas BF% reflects BMI, the BMI ratio (present to age 20), and lymphocyte count. In addition to BMI and SMI, changes in BF% should also be noted in underweight women.
骨骼肌质量指数（SMI）和体脂百分比（BF%）是体重指数（BMI）的组成部分，但被认为发挥着独立作用。我们旨在阐明在体重过轻的女性中，SMI和BF%是否与独立于BMI的营养指标相关。这项回顾性观察研究共纳入了102名年龄在20至65岁之间的女性，她们在2022年至2024年期间因体重指数（BMI）<17.5而被转诊至门诊营养评估诊所。我们以SMI和BF%作为自变量，以BMI、BMI比值（当前值与20岁时比值）、握力和生化营养指标（维生素B水平（ng/mL）、胆固醇水平（mg/dL）、淋巴细胞计数（/μL）和糖化血红蛋白A1c（%）水平）作为因变量进行多变量分析，并对年龄进行了校正。年龄为30.9±10.2岁（岁）、BMI为17.0±0.7的女性参与了本研究。BMI（kg/m）与SMI（kg/m）呈正相关（β（95%CI）：1.6[1.4,1.9]，<0.001）和BF%（0.2[0.1,0.2]，<0.001），而BMI比值（当前值与20岁时比值）仅与BF%呈正相关（0.5[0.05,0.9]，=0.03）。握力与SMI呈正相关（4.0[1.4,6.6]，=0.003），淋巴细胞计数与BF%呈正相关（β（36.2[6.0,66.5]，=0.02）。BMI与握力或淋巴细胞计数无关。维生素B、胆固醇和糖化血红蛋白A1c与SMI、BF%或BMI均无关。这些结果表明，SMI反映BMI和握力，而BF%反映BMI、BMI比值（当前值与20岁时比值）和淋巴细胞计数。在体重过轻的女性中，除了BMI和SMI外，还应注意BF%的变化。
