Relationship between sarcopenia and nonalcoholic fatty liver disease: The Korean Sarcopenic Obesity Study

Previous studies have shown that nonalcoholic fatty liver disease (NAFLD) and sarcopenia may share pathophysiological mechanisms, such as insulin resistance, inflammation, vitamin D deficiency, and decreased physical activity. However, their direct relationship has not been investigated. The association between NAFLD and sarcopenia was examined in 452 apparently healthy adults enrolled in the Korean Sarcopenic Obesity Study (KSOS), an ongoing prospective observational cohort study. The liver attenuation index (LAI), which was measured using abdominal computed tomography (CT), was used as a parameter for the diagnosis of NAFLD. Sarcopenia was defined using a skeletal muscle mass index (SMI) [SMI (%) = total skeletal muscle mass (kg) / weight (kg) × 100] that was measured by dual energy X-ray absorptiometry (DXA). After adjusting for age and sex, both SMI and LAI were negatively correlated with the homeostasis model assessment of insulin resistance (HOMA-IR) (P < 0.001) and high sensitivity C-reactive protein (hsCRP) (P < 0.001) as well as brachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness. Furthermore, SMI and LAI had positive relationships with high-density lipoprotein (HDL)-cholesterol, but both had a negative relationship with triglyceride, alanine aminotransferase (ALT), and total body fat. In a multiple logistic regression analysis, the odds ratio for NAFLD risk was 5.16 (95% confidence interval [CI] = 1.63-16.33) in the lowest quartile of SMI compared to the highest after adjusting for potential confounding factors. Conclusion: Individuals with lower muscle mass exhibited increased risk of NAFLD. This result may provide a novel insight into the mechanism linking between sarcopenia and NAFLD.