Low muscle mass is associated with metabolic syndrome only in nonobese young adults: the Korea National Health and Nutrition Examination Survey 2008-2010

Little is known about the relationship between body composition and metabolic risk factors in young adults. We hypothesized that low muscle mass (LMM) is associated with metabolic syndrome (MetS) and its components in young adults and that the associations vary by obesity. A cross-sectional analysis was conducted using the Korea National Health and Nutrition Examination Survey data. In total, 5300 young adults aged 19 to 39 years were evaluated. Low muscle mass was defined as an appendicular skeletal muscle mass/weight less than 1 SD below the mean for each participant's corresponding sex and age group. Obesity was defined as a body mass index greater than or equal to 25 kg/m2. The prevalence of LMM was higher in obese than nonobese participants (37.6% vs 9.6%). In the nonobese participants, the prevalence of MetS, high waist circumference, high triglycerides, and high blood pressure was significantly greater in the LMM group than in the high muscle mass group. In the nonobese group, compared with high muscle mass participants, those with LMM had odds ratios for MetS of 3.6 (95% confidence interval, 1.48-8.76; P < .001) and 3.6 (95% confidence interval, 1.48-8.71; P < .001) in men and women, respectively, after adjusting for confounding factors. However, no significant association of LMM with MetS or its components was found in obese participants. In conclusion, our results suggest that young adults with LMM may have a high risk of MetS, especially when they are nonobese. Interventions aimed at increasing muscle mass at younger ages may have the potential to reduce MetS.