Does Overweight and Obesity Impact on Self-Rated Health? Evidence Using Instrumental Variables Ordered Probit Models

This paper, for the first time, presents estimates of the causal impact of overweight and obesity on self-rated health (SRH) using instrumental variables (IV) econometric methods. While a number of previous studies have sought to better understand the determinants of SRH, there is no consensus in relation to the impact of overweight and obesity. Using data from a large nationally representative sample of Irish parents and their children, we estimate a range of ordered probit models to isolate the causal effect of overweight and obesity on SRH. Our data includes independently and objectively recorded weight and height measures for parents and their children and we instrument for parental body mass index (BMI) status using the BMI of a biological child. After controlling for a range of individual, socioeconomic, health and lifestyle related variables, we find that being overweight has a negligible impact on SRH, while being obese has a practically and statistically significant negative impact on SRH, with these effects most pronounced for those who are most obese. We find only minor differences in these effects across gender.