Low Levels of Alcohol Consumption, Obesity, and Development of Fatty Liver With and Without Evidence of Advanced Fibrosis

Background and Aims: The effects of low-level alcohol consumption on fatty liver disease and the potential for effect modification by obesity is uncertain. We investigated associations among low-level alcohol consumption, obesity status, and the development of incident hepatic steatosis (HS), either with or without an increase in noninvasive liver fibrosis score category (from low to intermediate or high category). Approach and Results: A total of 190,048 adults without HS and a low probability of fibrosis with alcohol consumption less than 30 g/day (men) and less than 20 g/day (women) were followed for up to 15.7 years. Alcohol categories of no, light, and moderate consumption were defined as 0, 1-9.9, and 10-29.9 g/day (10-19.9 g/day for women), respectively. HS was diagnosed by ultrasonography, and the probability of fibrosis was estimated using the fibrosis-4 index (FIB-4). Parametric proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). A total of 43,466 participants developed HS, 2,983 of whom developed HS with an increase in FIB-4 index (to intermediate or high scores). Comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for incident HS were 0.93 (0.90-0.95) and 0.90 (0.87-0.92), respectively. In contrast, comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for developing HS plus intermediate/high FIB-4 were 1.15 (1.04-1.27) and 1.49 (1.33-1.66), respectively. The association between alcohol consumption categories and incident HS plus intermediate/high FIB-4 was observed in both nonobese and obese individuals, although the association was stronger in nonobese individuals (P for interaction by obesity = 0.017). Conclusions: Light/moderate alcohol consumption has differential effects on the development of different stages of fatty liver disease, which is modified by the presence of obesity.