A multilevel study of effects of socioeconomic status, income inequality, and the built environment on adult obesity in China

The obesity epidemic has been consistently observed in both developed and developing countries. Despite the recognized deleterious effect of obesity on many chronic diseases and health conditions, the social determinants of obesity in developing countries remain poorly understood. Theoretically, social science studies on health have generally followed two research traditions: one examines socioeconomic disparities in health, and the other studies the effects of income inequality on health. They have tested three competing hypotheses -- the absolute income hypothesis, the relative income hypothesis, and the income inequality hypothesis.;Drawing upon both traditions, this dissertation aims to understand the patterns and social determinants of adult obesity in China. The obesity epidemic in China is complicated by the country's fast economic growth, diverse population, severe income inequality, profound ongoing socio-economic changes, and nutrition transitions. This dissertation has three specific objectives. The primary objective is to examine the effects of individual- and area-level socioeconomic status (SES) and income inequality on obesity. The secondary objective is to evaluate the influence of the built environment on obesity. The third one is to compare the difference in effects of SES and inequality on obesity across different built environment contexts. A multilevel framework approach is used to study these aims and the proposed hypotheses.;This dissertation has found that, at the individual-level, income and wealth are positively associated with body weight outcomes, whereas more education and a manual occupation are protective factors. The relative income is irrelevant to obesity. At the area-level, living in a less deprived community lowers one's risk of developing obesity while higher levels of urbanization increase the obesity risk. Income inequality is inversely associated with the obesity risk. The local built environment as assessed by the presence of fast food restaurants and sports facilities is modestly associated with the obesity risk. When stratified by built environment contexts, the associations between multidimensional SES and obesity vary across the contexts, but inequality effects on obesity remain significant and consistently negative. Education and income effects are pronounced in the context with the presence of fast food and absence of sports facilities. In summary, this dissertation has found some similar patterns of the SES-obesity associations that have been identified in the Western countries. In addition, to the best of our knowledge, this is the first study reporting consistently strong negative effect of inequality on obesity, opposite of what was found in developed countries.;This dissertation concludes that in China, the SES effects on obesity depend on the context of the built environment, whereas the negative effect of inequality on obesity is independent of such contexts. These findings contribute to the understanding of the effects of SES and income inequality on health and obesity, especially for developing countries.