Decomposing cross-country gaps in levels of obesity and overweight: does the social environment matter?

This paper examines the influence of environmental factors on weight gain and obesity. We take advantage of a markedly different pattern of obesity between Italy in Spain to undertake a non-linear decomposition analysis of differences in the prevalence of overweight and obesity between the two countries. The analysis is based on cross-sectional national surveys for 2003. We have attempted to isolate the influence of lifestyle factors, socio-economic and socio-environmental effects in explaining cross-country differences in BMI status. Our findings suggest that when the social environment (proxied by different measures of peer effects and regional BMI) is not controlled for, we explain about 27–42% of the overall Spain-to-Italy overweight and obesity gap. Differences in eating habits and education between the two countries are the main predictors of the gaps in obesity and overweight. However, when social environment is controlled for, our estimates explain between 76 and 92% of the obesity and overweight gap and the effect of eating habits are wiped out. These results suggest healthy body weight depends on cultural or environmental triggers that operate through individual level health production determinants.