Educational inequalities in obesity and gross domestic product: evidence from 70 countries.

Background: We test the reversal hypothesis, which suggests that the relationship between obesity and education depends on the economic development in the country; in poor countries, obesity is more prevalent in the higher educated groups, while in rich countries the association is reversed-higher prevalence in the lower educated.
Methods: We assembled a data set on obesity and education including 412,921 individuals from 70 countries in the period 2002-2013. Gross domestic product (GDP) per capita was used as a measure of economic development. We assessed the association between obesity and GDP by education using a two-stage mixed effects model. Country-specific educational inequalities in obesity were investigated using regression-based inequality indices.
Results: The reversal hypothesis was supported by our results in men and women. Obesity was positively associated with country GDP only among individuals with lower levels of education, while this association was absent or reduced in those with higher levels of education. This pattern was more pronounced in women than in men. Furthermore, educational inequalities in obesity were reversed with GDP; in low-income countries, obesity was more prevalent in individuals with higher education, in medium-income and high-income countries, obesity shifts to be more prevalent among those with lower levels of education.
Conclusions: Obesity and economic development were positively associated. Our findings suggest that education might mitigate this effect. Global and national action aimed at the obesity epidemic should take this into account.
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