Leveraging National Health Survey Data for Life-Course Analysis: Socioeconomic Positioning and Adult Obesity in South Korea Using KNHANES.

This study examines how nationally representative health survey data can be used to operationalise a life-course approach to health inequalities by examining socioeconomic inequalities and adult obesity in South Korea. Drawing on the life-course framework and using data from the ninth wave of the Korea National Health and Nutrition Examination Survey (KNHANES, 2022-2024), the study explores how multiple indicators of socioeconomic status (SES) are associated with obesity among adults aged 19 years and older (n=12,075). South Korea provides a valuable context for life-course research as a high-income country that has undergone rapid socioeconomic and demographic transformation within a single generation. KNHANES is one of the most comprehensive nationally representative health surveys in Asia and includes detailed information on education, income, employment, and demographic characteristics. Although cross-sectional, the dataset enables the examination of socioeconomic positioning and cumulative socioeconomic disadvantage using proxy indicators measured in adulthood. Obesity, defined using the Korean standard body mass index threshold (BMI ≥25 kg/m2), is analysed as a key outcome associated with long-term socioeconomic conditions. The findings reveal clear socioeconomic patterning in adult obesity. Lower educational attainment emerged as the most consistent predictor of obesity, while income and employment status showed more heterogeneous associations after adjustment. These findings are consistent with a life-course perspective in which cumulative socioeconomic conditions and structural constraints may shape obesity risk among adults. By demonstrating how nationally representative survey data can support life-course analysis in the absence of fully linked longitudinal systems, this study highlights the potential of existing population health datasets to inform future data linkage initiatives and comparative research on health inequalities. The findings contribute to ongoing efforts to leverage routinely collected data to support life-course approaches to improving population health and wellbeing.