Historically, in lower income countries, women with lower socioeconomic status (SES) have had a lower risk of overweight compared to their higher SES counterparts. However, with increasing rates of overweight worldwide, contemporary data suggest that even in some developing countries, lower SES women now have a higher risk of overweight compared to higher SES women. We use data from women (n=556,352) in 41 lower income countries to determine whether the prevalence of overweight has increased disproportionately among low SES women compared to high SES women during the last two decades. We also assess whether the direction of the relationship between SES and overweight has changed for women in these countries. Furthermore, we examine whether there are country-level contextual features that are saliently associated with comparatively faster overweight prevalence gains among low SES women. We find that the relation between SES and overweight has changed direction from positive to inverse in only five countries. However, in approximately 30-50% of the countries, the increases in overweight prevalence over time have been faster in the lowest SES populations compared to the highest SES populations. Country-level economic development was positively associated with faster increases in overweight prevalence among the lower wealth women. The fastest gains in low SES populations were seen in countries that had relatively higher GDP and lower levels of income inequality. We then use longitudinal data from adults in China (1989-2006) to track trajectories of BMI and overweight according to SES. We find larger increases in BMI and overweight over time for the lowest SES women compared to the highest, resulting in the emergence of a socioeconomic disparity in overweight. Opposite findings are seen for men; high SES men (versus low) have higher odds of overweight by the end of the survey. Overall, this study indicates that, predominantly, in lower income countries, low SES women are still less likely to be overweight than high SES women. However, a shift in the burden of overweight also appears to be underway, as the rates of overweight prevalence gains among low SES women are currently outpacing those among high SES women in these contexts
