Alcohol use disorder across the weight spectrum: a cross-sectional study from a Korean national survey

Background Findings on the relationship between weight status and alcohol use disorder (AUD) have been inconsistent. Therefore, this cross-sectional study investigated the relationship between AUD and body mass index (BMI) in a nationally representative sample of South Korean adults. Methods We analysed the data of 5,511 adults aged 18–79 years who participated in the 2021 National Mental Health Survey of Korea. AUD was diagnosed using the Korean version of the Composite International Diagnostic Interview. BMI was calculated using self-reported height and weight. Participants were categorised according to the World Health Organization Asia-Pacific criteria as underweight (< 18.5), normal weight (18.5–23), overweight (23–25), and obese (≥ 25). Gender-stratified multivariate logistic regression analyses were conducted after adjusting for socio-demographic variables and drinking patterns. Potential nonlinear associations were evaluated using quadratic terms and generalised additive models. Results Among 3,468 past-year drinkers, 144 (4.2%) met the AUD criteria. AUD prevalence was highest in the underweight group and decreased with increasing BMI in both genders. In men, overweight and obesity were associated with significantly lower odds of AUD (OR 0.537, 95% CI 0.327–0.882; OR 0.353, 95% CI 0.196–0.634, respectively). No significant association was found in women after adjustment. Supplementary analyses suggested a nonlinear U-shaped association between AUD and BMI in men. Conclusions The association between BMI and AUD differed by gender. In men, overweight and obesity were associated with lower odds of AUD, whereas a potential U-shaped pattern with increased odds at both BMI extremes. No significant associations were observed among women.