Background: This paper contributes to the debate on the North-South health divide by disentangling the conditioning factors responsible for regional differences in BMI. Specifically, this paper analyses differences in BMI between northern and southern Spanish regions, a country characterized by important geographical disparities in BMI and other health outcomes, as well as by the decentralized structure of its National Health System (NHS).
Method: First, we decompose the average North-South BMI gap into the contribution of explained and unexplained factors using the Oaxaca-Blinder decomposition. Second, we perform a distributional analysis by applying the Recentered Influence Function (RIF) Regression and the corresponding decomposition, to analyse BMI differentials along its unconditional distribution.
Results and Conclusions: Our findings indicate that North to South differences in BMI are significant only for women and a large share (74%) of this gap is explained by differences in endowments (basically years of schooling) to the detriment of women living in the South. Moreover, the explained (unexplained) portion of the gap steadily increases (decreases) along the BMI distribution, suggesting that what really matters to deal with the obesity epidemic among overweight women is focusing attention on regional disparities in observed endowments, human capital being the main driver.