Wealth and Weight: The Impact of the BMI According to Income in European Countries

This study analyses the evolution of body mass index (BMI) as income increases across the population, controlling for age, sex, educational level, marital status and some lifestyle habits. To this end, a quantile regression, an econometric technique that readjusts the weights of the variables in each quantile to minimize deviations, has been carried out, where the variable that orders the sample is income. We use 316,777 observations from the European Health Interview Survey (EHIS) for these regressions. This approach allows us to separate the regression analyses for low-, middle-, and high-income groups, evidence that as individual income increases, BMI tends to rise. Consequently, individuals with higher incomes exhibit higher BMI levels. Additionally, the estimated parameters for explanatory variables increase with income, signifying that wealthier individuals not only have a greater likelihood of increased BMI but also that socio-economic factors influencing BMI – whether positively or negatively – evince a stronger impact as income levels rise.