Determinants of obesity: The role of sociodemographic factors, health behaviors, and quality of life in Spanish workers.

BACKGROUND: Obesity remains a major global health challenge with profound clinical, psychosocial, and economic consequences. Although body mass index (BMI) is widely used, alternative adiposity indices such as waist-to-height ratio (WtHR), Clínica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE), and the Metabolic Score for Visceral Fat (METS-VF) may offer superior insights into central adiposity and cardiometabolic risk. Furthermore, the relationship between obesity and health-related quality of life (HRQoL) remains insufficiently explored in occupational settings, where lifestyle, socioeconomic, and psychosocial factors converge. METHODS: We conducted a cross-sectional study of 100,014 Spanish workers (18-69 years) who underwent standardized occupational health assessments between 2021 and 2023. Anthropometric and biochemical data were collected to calculate BMI, WtHR, CUN-BAE, and METS-VF. Sociodemographic characteristics, lifestyle habits (smoking, physical activity, and Mediterranean diet adherence), and HRQoL (12-Item Short Form Health Survey, SF-12) were also recorded. Logistic regression models were used to evaluate associations between obesity indices and sociodemographic, behavioral, and HRQoL variables, adjusting for potential confounders. RESULTS: Obesity prevalence varied markedly depending on the index employed, ranging from 17.2% with BMI to over 30% with CUN-BAE and METS-VF. Across all measures, older age, male sex, lower social class, smoking, physical inactivity, and poor adherence to the Mediterranean diet were significantly associated with higher odds of obesity. Importantly, workers with lower SF-12 physical and mental component scores consistently showed greater obesity risk, even after adjustment. These findings confirm the bidirectional interplay between excess adiposity and diminished quality of life. CONCLUSIONS: In this large occupational cohort, obesity was strongly associated with adverse sociodemographic profiles, unhealthy lifestyles, and impaired HRQoL. Our results highlight the limitations of BMI alone and underscore the value of alternative adiposity indices in public health surveillance. Integrating HRQoL assessment into obesity prevention and workplace health programs may enhance early detection, risk stratification, and the design of holistic interventions targeting both physical and psychosocial well-being.