Metabolic dysfunction-associated steatotic liver disease (MASLD) is a new term used to describe steatotic liver disease linked to metabolic syndrome. MASLD is currently recognized as the most common cause of chronic liver disease and a major factor contributing to liver-related morbidity and mortality. Globally, the incidence and prevalence of nonalcoholic fatty liver disease (NAFLD), now a part of the MASLD spectrum, have risen, driven by the obesity epidemic, which affects populations worldwide, including in Korea. Research suggests that the prevalence of NAFLD in Asian countries is comparable to, and in some cases exceeds, that in Western countries. A study by Youn Huh et al. (2021) estimated that 15.82% of Asians were affected by NAFLD, based on criteria like hepatic steatosis or fatty liver index.NAFLD progresses through various stages, including fibrosis, cirrhosis, steatohepatitis, simple steatosis, and, in some cases, may even advance to hepatocellular carcinoma. In cases where only steatosis is present, the disease is relatively silent and follows a benign course (Puthija Kumaravalli et al., 2023). Mild hepatic steatosis, also known as grade 1 fatty liver, represents the least severe stage of NAFLD and involves minimal fat accumulation in liver cells. While often asymptomatic, it reflects the early onset of the disease.Studies indicate that patients with moderate to severe NAFLD are more likely to experience sarcopenia and show reduced muscle mass in both the trunk and lower limbs compared to those with mild NAFLD. Sarcopenia, characterized by a decline in muscle mass and strength, has become increasingly prevalent among older adults and individuals with severe illnesses like liver cirrhosis and cancer. Recently, the relationship between sarcopenia and MASLD has garnered significant attention. Prior research suggests that correcting muscle mass relative to height may underestimate the association between physical performance and muscle mass. Instead, BMI may provide a more accurate measure when considering body size, as it shows a stronger correlation with physical dysfunction and muscle weakness.the purpose of my study is to use a body composition analyzer to assess changes in fat and muscle mass across different stages of NAFLD. Using noninvasive tools like the BODY COMPOSITION ANALYZER MEDIANA, body composition analysis is now a practical method for evaluating individuals with NAFLD. However, there is limited clarity on measuring physical performance in these patients. Consequently, another objective of my study is to evaluate functional capacity using the 6-minute walk test (6MWT).By assessing changes in body composition and functional capacity at different stages of MASLD, this study aims to identify functional limitations that may accelerate disease progression. Early management strategies may help patients maintain or regain normal functioning, underscoring the importance of this research in improving patient outcomes.