Background: Biocultural approaches to health research recognize that meaning and materiality mutually co-construct outcomes. However, both the "bio" and "cultural" are often unproblematized and analyzed through hegemonic, ethnobiocentric Western lenses. Drawing on theories of "biological normalcy," "emic validity," and "cultural consonance," this research analyzes how cultural meanings associated with men's body shape relate to men's vulnerability to obesity, body dissatisfaction, and disordered eating in South Korea. Methods: 82 young South Korean men (mean age=26.2±3.3 years) living in Seoul completed a survey assessing local understandings of what body types were considered "too thin" and "too fat," as well as their current and ideal shapes, on a figure rating scale. Cultural consensus analysis (CCA) was used to test for the presence of single cultural model of body shape. Based on CCA results for male Korean perceptions of "too thin" or "too fat," respondents were categorized into locally defined categories using their self-reported current shapes. ANOVA was used to examine variation in health outcomes across self-perceived, culturally specified body shapes. Results: CCA determined a single, strongly shared cultural model of body shape in this sample. Men whose bodies were locally characterized as "too thin," "balanced," and "too fat" varied in body mass index (BMI), body dissatisfaction (Male Body Attitudes Scale), disordered eating risk (EAT-26), and dieting (EAT-26). Men with "too fat" shapes reported the lowest average cultural consonance (an emically valid measure of male attractiveness) across body types, as well as the greatest engagement in dieting and risk for eating disorders. 41% of the men with "too fat" shapes exceeded the EAT-26 cutoff of 18 for Korean men compared to 11% of "too thin" and 14% of "balanced" men (p = 0.014). Further, "balanced" shapes reported the highest cultural consonance but were, on average, overweight by BMI (>23 by WHO standards for the Asian-Pacific Region). Conclusions: A biocultural approach challenges ethnobiocentrism in obesity research and offers insights into the importance of culture to understanding health beliefs, behaviors, outcomes.