Community built environment and multilevel social determinants of obesity: Lessons from China

The obesity epidemic has been consistently observed in both developed and developing countries. However, effects of the community built environment on multilevel social determinants of obesity remains unknown in developing nations. We synthesized literature on socio-economic (SES) gradients in health and income inequality effects on health and analyzed data from 2006 China Health and Nutrition Survey (N=9,586) to understand how multilevel social determinants of obesity varied by different types of built environments assessed by the presence/absence of local fast food restaurants and sports facilities. At the individual level, adjusting for demographic characteristics, top quintiles of income and wealth were positively associated with obesity (OR=1.45 and 1.31, respectively, p<0.01), whereas education and manual occupation were negatively associated with obesity (OR=0.73, p<0.05 and OR=0.72, p<0.01, respectively); however, relative income had no significant effect on obesity. At the community-level, adjusting for community characteristics, income inequality was inversely associated with obesity (OR=0.93, p<0.001). When stratified by built environmental contexts, multidimensional SES effects on obesity varied across contexts; however, inequality effects on obesity remained significant and consistently negative (OR ranged from 0.92 to 0.94, p<0.001). Education and income effects were pronounced in communities with the presence of fast food and absence of sports facilities. Patterns of SES and inequalit¬¬y affecting obesity risks in developing countries can be uniquely different from that in developed societies. To the best of our knowledge, this is the first study reporting consistently strong negative effects of inequality on obesity, opposite of Wilkinson's income inequality hypothesis of health in developed countries.