OBJECTIVE: To update the social distribution of women's obesity in the developing world and, in particular, to identify the specific level of economic development at which, if any, women's obesity in the developing world starts to fuel inequities in health. DESIGN: Multilevel logistic regression analyses applied to anthropometric and socioeconomic data collected by nationally representative cross-sectional surveys conducted from 1992 to 2000 in 37 developing countries within a wide range of world regions and stages of economic development (gross national product (GNP) from US$190 to 4440 per capita). SUBJECTS: In total, 148 579 nonpregnant women aged 20–49 y.

MEASUREMENTS: Body mass index to assess obesity status; quartiles of years of education to assess woman's socioeconomic status (SES), and GNP per capita to assess country's stage of economic development. RESULTS: Belonging to the lower SES group confers strong protection against obesity in low-income economies, but it is a systematic risk factor for the disease in upper-middle income developing economies. A multilevel logistic model—including an interaction term between the country's GNP and each woman's SES—indicates that obesity starts to fuel health inequities in the developing world when the GNP reaches a value of about US$2500 per capita. CONCLUSIONS: For most upper-middle income economies and part of the lower-middle income economies, obesity among adult women is already a relevant booster of health inequities and, in the absence of concerted national public actions to prevent obesity, economic growth will greatly expand the list of developing countries where this situation occurs.