People genetically predisposed toward obesity — particularly females — are more likely to have lower incomes and household wealth later in life, mostly due to attaining less education throughout their lives, a recent study suggests.
The study, “Effect of Genetic Propensity for Obesity on Income and Wealth Through Educational Attainment,” was published in the journal Obesity.
The relationship between money and obesity is complicated and likely bidirectional. That is, being obese may decrease income (for example, by causing health problems that reduce workplace productivity), but having less money may predispose a person toward lifestyle choices that favor obesity (eating more fast food, for instance).
By focusing on the genetics that predispose toward obesity, which, unlike obesity itself, aren’t really affected by lifestyle and environmental factors, researchers can try to understand how being heavier might affect a person economically.
To this end, researchers used data from the U.S. Health and Retirement Study (HRS), in combination with a genetic signature of body mass index (BMI), to try to better understand this relationship.
The HRS includes data (economic, health-related, genetic, etc.) on a panel of Americans older than 50 and their spouses. The researchers used data on 5,962 individuals age 50–65 who were of European descent. This specificity was chosen to avoid other confounding variables, but the researchers acknowledged that restricting their analysis in this way, both in terms of age and race, may limit how their results can be generalized.
The genetic signature, termed genetic risk score for BMI (GRS-BMI), was derived from a previous study that identified genetic variations that explained 21.6% of actual BMI.
Using statistical models, the researchers assessed to what degree GRS-BMI could explain individual income and household wealth. In the whole population, individual income was not significantly associated with GRS-BMI, but household wealth was.
They examined this relationship while also taking into account educational attainment (measured as the number of years of school a person attended), which would be expected to have a fairly direct effect on income and wealth.
In this model, both income and wealth were associated significantly with GRS-BMI; that is, people who were genetically predisposed toward being heavier tended to have lower income and less household wealth, and this was tied to those same people being more likely to have attained low educational level.
Interestingly, when the researchers divided the data based on sex (2,790 males and 3,172 females) in this model, there was still a strong association between education-mediated GRS-BMI for females, but for males the relationship was no longer statistically significant.
“These results are consistent with earlier studies indicating the absence of a negative correlation between weight and income among males,” the researchers wrote. “Moreover, the larger effects for females compared with males may be due to greater labor market taste-based discrimination faced by females.”
Further research will be needed to fully understand how body weight affects education and, by extent, economic status. The researchers even suggested that genetic tests of GRS-BMI or similar indices might allow for “interventions to improve educational attainment and subsequently later-life income and wealth.”