Association Between Bioimpedance-Determined Metabolic Age and MASLD Risk Scores in Spanish Workers.

: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver disorder with significant metabolic implications. Metabolic age, determined through bioimpedance analysis, has emerged as a potential indicator of overall metabolic health. The objective of this study is to evaluate the association between metabolic age and MASLD risk scores in a cohort of Spanish workers. : A cross-sectional study was conducted on 8590 Spanish workers who underwent annual occupational health examinations between 2019 and 2020. Metabolic age was determined using bioelectrical impedance analysis, and the Avoidable Lost Life Years (ALLY) index was calculated as the difference between their metabolic and chronological age. MASLD risk was assessed using various validated scales, including the Fatty Liver Index (FLI), Hepatic Steatosis Index (HSI), Zhejiang University Index (ZJU), Fatty Liver Disease Index (FLD), and Lipid Accumulation Product (LAP). A multinomial logistic regression analysis was performed to examine the association between metabolic age and MASLD risk scores, adjusting for sociodemographic and lifestyle variables. : Higher metabolic age values were observed in individuals with greater MASLD risk across all evaluated scales. The mean metabolic age was consistently lower in women compared to men, and these differences were statistically significant ( < 0.01). Multinomial logistic regression analysis revealed that the strongest associations with increased metabolic age were found for MASLD risk scores, physical inactivity, and poor adherence to the Mediterranean diet. ROC curve analysis demonstrated a high predictive capacity for the FLD (AUC: 0.935 in women and 0.917 in men) and FLI (AUC: 0.900 in women and 0.833 in men), with high Youden index values. : Metabolic age is significantly associated with MASLD risk, suggesting its potential as a non-invasive biomarker for identifying individuals with a higher risk for metabolic liver disease. Lifestyle factors, including physical activity and dietary patterns, play a crucial role in modulating metabolic age, highlighting the importance of targeted interventions for MASLD prevention. Further research is warranted to validate metabolic age as a prognostic tool in MASLD risk assessment.