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The following is a summary of “Body mass index and waist-to-height ratio effect on mortality in non-alcoholic fatty liver: revisiting the obesity paradox,” published in the December 2024 issue of Endocrinology by Jiang et al.    

Non-alcoholic fatty liver disease (NAFLD) is a common condition associated with obesity, but some studies suggest a paradoxical survival advantage in individuals with excess weight and NAFLD.  

Researchers conducted a retrospective study to explore the impact of body mass index (BMI) and waist-to-height ratio (WHtR) on mortality in individuals with NAFLD.  

They examined participants with NAFLD diagnosed through ultrasound from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). Mortality risk was assessed using multivariate Cox regression for BMI and WHtR.  

The results showed that during a median follow-up of 20.3 years, individuals with overweight (HR 0.926, 95% CI 0.925–0.927) or obesity (HR 0.982, 95% CI 0.981–0.984) had lower mortality risks than those with normal weight. After adjusting for smoking and excluding the first 5 years, the paradox disappeared (HR 1.046, 95% CI 1.044–1.047 for overweight; HR 1.122, 95% CI 1.120–1.124 for obesity class I). The paradox was less pronounced with WHtR, which showed significant differences only in the second quartile (HR 0.907, 95% CI 0.906–0.909) compared to the first quartile and was resolved after appropriate adjustments. When both BMI and WHtR were considered together, higher adiposity levels, indicated by WHtR, were associated with a greater mortality risk, unlike BMI (P<0.05).  

They concluded that the obesity paradox in individuals with NAFLD was explained by smoking and reverse causation, WHtR was a better predictor of mortality than BMI.  

Source: frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2024.1419715/full