Mediation of blood lipid levels on the relationship between BMI/WHR and liver function in normal, overweight, and obese individuals

This study investigates the impact of Body Mass Index (BMI) and Waist-to-Hip Ratio (WHR) on Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) levels, as well as the mediating role of lipid parameters: total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Understanding these associations is crucial for exploring the interplay between obesity, fatty liver disease, liver function impairment, and dyslipidemia. Conducted in Nantong City, Jiangsu Province, from July to September 2024, this research used a convenience sampling method involving 1,816 participants. Generalized Linear Models (GLM) and Restricted Cubic Splines (RCS) analyzed BMI/WHR's relationship with ALT/AST, while causal mediation analysis assessed lipid parameters' mediating effects. The findings indicated a positive correlation between both BMI and WHR with AST and ALT levels. The lipid indicators significantly mediated the relationship between BMI/WHR and AST/ALT, suggesting that obesity correlates with elevated liver enzyme levels and that blood lipid abnormalities may play an important intermediary role. This study enhances the understanding of interactions among obesity, fatty liver disease, liver function impairment, and dyslipidemia. It underscores the importance of addressing lipid abnormalities in managing obesity-related liver disease and calls for future research to explore underlying mechanisms and develop targeted interventions.