Background The global obesity epidemic is spreading rapidly with a social distribution that varies according to the level of economic development: as countries develop, the burden of obesity appears to shift from the rich to the poor. Studying these changes as they occur can help shed further light on the social processes that fuel the obesity epidemic and determine its social distribution. Egypt provides a case in point for this research. Findings would be relevant to other low-and-middle income countries but may also be generalisable to an extent to poor communities in high income countries.

Objectives To examine the social distribution of obesity among Egyptian women by socio-economic status and how it has changed over time.

Design and methods Retrospective analysis using four nationally representative cross-sectional surveys (Demographic and Health Surveys) conducted in Egypt between 1995 and 2008. Socio-economic status was defined as the highest reported educational level attained.

Setting Egypt.

Participants 64 605 women between 15 and 49 years excluding pregnant women.

Main outcome measure Obesity: defined as BMI (height/weight²) equal to or above 30.

Results The overall level of obesity among Egyptian women rises from 30% in 1995 (urban=33%; rural=27%) to 40% in 2008 (urban=43%; rural=34%). Among urban women, in 1995, the prevalence of obesity is lower in the group without education (24%; 95% CI 19 to 29) in comparison to the group with secondary education (33%; 95% CI 29 to 37). In 2008, the prevalence of obesity has risen in a statistically significant manner in both groups compared with 1995. In addition, the prevalence in the group without education (45%; 95% CI 41 to 50) appears to have exceeded the prevalence in those with secondary education (41%; 95% CI 38 to 44). Although there is overlap in the CI at the 95% level, the overall trend suggests that the social gradient in obesity may be reversing, as predicted elsewhere.

Conclusion Egypt provides a dynamic model of the reversal of the social gradient of obesity. Further analysis of Demographic and Health Surveys using other indicators of socio-economic status and risk factors for obesity such as consumption of fruit and vegetables may shed light on the processes behind the probable gradient reversal, and the factors putting the poor at increased risk of obesity. This is important in informing urgent prevention efforts at a population level.