A significant association of non-obese non-alcoholic fatty liver disease with sarcopenic obesity

Non-alcoholic fatty liver disease (NAFLD) is significantly related to sarcopenia as well as obesity and its associated comorbidities. This cross-sectional study aims to examine the association between four body composition phenotypes (standard, obesity alone, sarcopenia alone, sarcopenic obesity) and non-obese NAFLD, or obese NAFLD. Reduced muscle mass and high percentage of body fat mass was measured by dual-energy x-ray absorptiometry, and body composition phenotypes were determined, according to Asian criteria for sarcopenia. Based on body mass index (BMI) cut-off point (25 kg/m2) and hepatic steatosis on ultrasound, 748 subjects who underwent a health checkup were enrolled and divided into three groups: non-obese NAFLD, obese NAFLD, and no steatosis. Of 563 subjects (64.1 ± 13.0 years) without secondary causes for steatosis, the overall prevalence of non-obese NAFLD and obese NAFLD were 17% and 16%, respectively. The former prevalence remained relatively constant at around 20% from the 50s to 80's, while the proportion of sarcopenic obesity in all subjects increased gradually with age, reaching 18% in the 80's. Multivariate analysis demonstrated a significant association between sarcopenic obesity and non-obese NAFLD after adjusting for confounders (odds ratio = 2.367, 95% confidence interval = 1.317–4.254, P = 0.004). On the other hand, no significant association was found between obesity alone and obese NAFLD, when BMI and visceral adipose tissue were added as confounders, although 91% of obese NAFLD was included in obesity alone phenotype. Non-obese NAFLD had a significant association with sarcopenic obesity, independent of metabolic confounders. Early treatment intervention for non-obese NAFLD could suppress the deterioration of sarcopenic obesity because non-obese NAFLD might be a risk factor for sarcopenic obesity.