Prevalence and Trends of Obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease among Adults in the United States

OBJECTIVES: Metabolic dysfunction-associated steatotic liver disease (MASLD) affects approximately 100 million individuals in the United States. Previous studies have reported a significant association between obesity and MASLD. The objective of our study was to examine the relationship between obesity and population-level trends in MASLD prevalence among US adults aged 20 years and older. METHODS: We conducted a retrospective analysis of serial cross-sectional data from the National Health and Nutrition Examination Survey cycles (1999-2018). MASLD was defined using two criteria: (1) US Fatty Liver Index (USFLI) ≥30 or (2) cardiometabolic risk factors (≥1) with controlled attenuation parameter ≥288 dB/m (2017-2018 only). Temporal trends in the prevalence of MASLD and obesity were analyzed using logistic regression with the midpoint of a 2-year survey cycle as a continuous independent variable. Adjusted odds ratios (ORs) quantified obesity's association with MASLD trends, controlling for age, sex, race/ethnicity, and survey design variables. RESULTS: ) and 33.49% met MASLD criteria (USFLI ≥30). MASLD prevalence increased from 30.20% (95% confidence interval [CI] 26.57%-33.83%) in 1999-2000 to 38.64% (95% CI 35.47%-41.80%) in 2017-2018 mirroring rising obesity rates (30.26%-43.51%). MASLD prevalence varied significantly across different demographics, with the highest rates observed in older adults, males, and Mexican Americans. Obesity was associated with a 14.05-fold higher odds of MASLD (95% CI 12.62-15.65). CONCLUSIONS: MASLD prevalence trends closely parallel the obesity epidemic, with obesity strongly associated with MASLD risk. The differential prevalence rates among older adults, males, and Mexican Americans highlight the need for targeted prevention strategies, including obesity management.