Causal effects of socioeconomic status on central adiposity: Evidence using panel data from urban Mexico

The current economic growth and increase in urbanization has led to the adoption of new lifestyles in middle-income countries such as Mexico. Associated with overweight, obesity and chronic diseases, the nutrition transition process reveals important socioeconomic issues. Using panel data from the Mexican Family Life Survey, the purpose of the study is to estimate causal effects of household socioeconomic status (SES) on nutritional outcomes among Mexican adults from urban areas. We divide the analysis into two steps. First, using a mixed clustering procedure, we distinguish four socioeconomic classes based on income, education and occupation dimensions: (i) a poor class; (ii) a lower-middle class; (iii) an upper-middle class; (iv) a rich class. Second, using an econometric framework adapted to our study (the Hausman-Taylor estimator), we measure the impact of belonging to these socioeconomic groups on individual anthropometric indicators, based on the body-mass index (BMI) and the waist-to-height ratio (WHtR). Our results make several contributions: (i) we show that a new middle class, rising out of poverty, is the most exposed to central adiposity; (ii) as individuals from the upper class seem to be fatter than individuals from the upper-middle class, we can reject the assumption of an inverted U-shaped relationship between socioeconomic and anthropometric status as commonly suggested in emerging economies; (iii) the influence of SES on anthropometric indicators appears to be particularly strong for men.