Adding More Weight (Pun Intended) To The Gender Pay Gap Myth

Regular readers of economics will know that despite common myths to the contrary, the reality is there isn't much of an unfair pay gap between genders. As service-based industry has emerged more prominently, coupled with increased technology that make domestic jobs less time-consuming, and women's lib, the wage gap that used to exist has narrowed so much that it has equalised. In fact, if you measure just male and females in their 20s and 30s, females earn slightly more. Obviously this tails off in the late 30s and 40s as motherhood becomes the primary driving force in the re-introduction of a wage gap - but it's not to do with discrimination, it is to do with biology and life choices.

There's an interesting paper from health economist Heather Brown who observes that single women with a higher BMI (body mass index) tend to earn higher wages than similar women with a lower BMI. Married men also have a wage rate that is positively related to their BMI - the more weight they carry the higher their wages tend to be. The opposite is true for single men and married women - there is a negative correlation between their age rate and BMI - the more weight they carry the lower their wages tend to be.

Why is this? The most likely reason is that being overweight doesn't disadvantage men in the market for marriage to anything like the same extent that it disadvantages women - but it does encourage women to invest more in their careers to compensate for the disadvantage in the marriage market. Or to put it another way, very attractive slimmer women have a much higher likelihood of marrying financially well off men than overweight women, which means according to Heather Brown's studies they do not have quite such high incentives to invest in their careers as women who are disadvantaged in the marriage market.

Studies by Pierre-Andre Chiappori, Sonia Orefice ad Climent Quintana-Domeque also show that as a result of this, overweight women are more likely to marry low-income men. If single, heavy men know that a) they are less likely to marry, and b) if they do marry they are more likely to marry a low-income man, it makes sense that there would be a pattern whereby heavier women invest more in their careers.

The flip side of the coin, however, is that all the slim, attractive women under-investing in their careers because of expectation of marrying higher-income men may be affecting the 'pay gap' statistics - but in a way that makes the lack of a gender pay gap even more substantiated. That is to say, not only is it not the case that there is no gender pay gap due to discriminatory forces, it may well be the case that women in their 20s and 30s are earning slightly more than men even though a significant number of them (those with a lower BMI) are under-investing in their careers due to future marital expectations.