The relationship between body mass index and income: Using genetic variants from HUNT as instrumental variables

Abstract

Several studies have estimated effects of body mass index (BMI) on labour market outcomes, and these studies have mixed findings. A significant challenge has been to adequately control for omitted variables, selection, reverse causality, and measurement error. We examine the impact of BMI on income using genetic variants as instrumental variables for BMI. Individual‐level pre‐tax income from tax records was merged with health survey data containing measured height and weight, and data on genetic variants. The analyses were stratified by sex and a variety of methods were used to explore the sensitivity and validity of the instrumental variable (IV) strategy. For females we found that BMI had a negative effect on the logarithm of income. The effect estimated from the IV models (−0.02) was larger than the effect estimated from naïve ordinary least squares regressions (−0.01). For males, the coefficients for the effect of BMI on income were imprecise, and both positive and negative coefficients were estimated depending on the estimation method. Our results suggest that females are susceptible to reduced income levels following increased BMI.

The association of obesity-related traits on COVID-19 severity and hospitalization is affected by socio-economic status: a multivariable Mendelian randomization study

“…economic difficulties, the affordability of energy-dense foods, low dietary quality, poor health literacy, occupational status and lifestyle behaviours, such as low physical activity and sedentary behaviours. 55–60 There is also evidence that obesity-related traits can affect SES via multiple factors that have been previously grouped into three categories: 61 (i) health effects: high BMI increases the risk of several chronic diseases, which could affect work ability and subsequently income; 61 , 62 (ii) reduced job performance: body shape affects health capital, presenteeism, self-esteem and employment status, which impact income; 63 , 64 (iii) discrimination from employers. 65 , 66 Accordingly, there are likely multiple pathways by which income could affect the association between obesity-related traits and COVID-19 outcomes.…”