Life-course social disparities in body mass index trajectories across adulthood: cohort study evidence from China Health and Nutrition Survey

Background The social disparities in obesity may originate in early life and adult social class. There are various developmental trajectories of overweight/obesity in adulthood. It is unclear how the intergenerational mobility of socioeconomic status influences adult overweight/obesity in China. Methods We used longitudinal data from ten waves of the China Health and Nutrition Survey (CHNS) between 1989 and 2015 for our analysis. The group-based trajectory modeling was used to identify BMI trajectories in adulthood. Multinomial logistic regression was adopted to assess the associations between SES and adult BMI trajectories. Results Among a total of 3,138 participants, three latent clusters, including normal-stable BMI (51.4%), progressive overweight group (39.8%), and progressive obesity group (8.8%), were identified. High father’s occupational position, high participants’ occupation position and educational attainment, respectively, were associated with greater obesity risk. Compared to a stable low life course SES trajectory, a stable high life course SES trajectory was associated with a 2.35-fold risk of obesity, and upward and downward social mobility trajectories increased the risk for overweight/obesity. Individuals in the highest relative to the lowest life course cumulative socioeconomic score group had around twice risk of obesity. Conclusions The results emphasize the role of the high SES in early life and life-course SES accumulation, in the obesity intervention in China. Funding All the work was supported by the National Natural Science Foundation of China (Grant Nos. 72174167, 81602928) and Natural Science Foundation of Shaanxi (2021JM-031).