Body Weight, Work, and the Marriage Market: An Interview with Shoshana Grossbard

Heavier White women who are married generally work more hours than married women who are thinner because they tend to marry men who earn less money and appear to have "less access" to their husband's income. That's one of the findings in a recent study led by Dr. Shoshana Grossbard, a professor of economics at San Diego State University. A pioneer in the study of the economics of marriage and the household, Dr. Grossbard is a fellow at the IZA Institute in Bonn, Germany, and the founding editor of the journal, Review of Economics of the Household. One of her recent areas of research involves studying the association between body mass index (BMI) and hours of work to determine whether the marriage market is the main mechanism driving this association. Her study, “Marriage Markets as Explanation for Why Heavier People Work More Hours,” was co-authored by Sankar Mukhopadhyay and published in the IZA Journal of Economics in 2017. In the following interview with IFS, Dr. Grossbard explains the study and its findings. 

Alysse ElHage: Tell us about your study’s design and the key questions you sought to answer about how BMI impacts how many hours individuals tend to work and the link to marriage?

Shoshana Grossbard: Our research focused on the impact of BMI on market hours of work and whether this impact operates via mechanisms related to marriage markets, such as intra-marriage financial transfers, bargaining about access to consumption, or in the case of singles, marriage expectations or predicted spousal income and access to household income.

We used data from two cohorts of the National Longitudinal Survey of Youth: the 1979 cohort and the 1997 cohort (NLSY79 and NLSY97) and examined the association between BMI and hours of work for men and women who are either married to their first spouse or are unmarried. Since NLSY interviews all eligible youths in an eligible household, we know the relevant information for the siblings of respondents as well. This allows us to use two strategies to establish causality: We use sibling fixed effects (FE) and instrumental variable (IV) regression with same-sex sibling BMI as an instrument to establish causality. Our data also includes relatively large samples of Blacks and Hispanics, thus allowing us to compare our findings for various ethnic groups. However, we do not have data on spouse’s BMI, which prevents us from testing predictions regarding the effects of a spouse’s relative weight on hours worked. 

Alysse ElHage: The study notes that higher body weight is more likely to affect women’s work than men’s work. Why is this the case, and what does it have to do with marriage? 

Shoshana Grossbard: We think that women’s value in the marriage market is affected more by looks and body weight than is the case with men’s value in the marriage market, and that variation in women’s value in the marriage market is more likely to translate into variation in hours of work (among heterosexuals, women are more likely to be paid for what I call WIHO by their husbands than men).

WIHO is derived from the words “Work in Household.” It consists of activities that the person considers work because she or he would rather do something else, but the person is doing it for the benefit of another adult in the household, possibly a husband or a wife. Many people get “paid” for their WIHO in the sense that their spouse gives them access to money or goods, and to some degree, that is compensation for the WIHO. If you make less money than your spouse and do more household production and the two of you share incomes you are de facto getting paid for your WIHO.

Alysse ElHage: You began with the theory that higher BMI men and women would work more hours than lower BMI men and women (for both married and single individuals). Let’s look at married individuals first. What did you find? 

Shoshana Grossbard: We found a one-unit increase in BMI leads to a 2.0% increase in hours worked among White married women; but no significant effect for men. In the case of men, changes in BMI are not associated with changes in hours worked. 

Alysse ElHage: What about singles—did you find an association between higher BMI and hours of work for single men and women?

Shoshana Grossbard: We found a one-unit increase in BMI leads to a 1.4% increase in hours worked among White single women. BMI is also positively associated with hours of work of White and Black single men. The result for White single men carries over when the IV method, or instrumental variable method, is used (we used the BMI of a sibling to capture the genetic tendency of the individual to be of a certain weight per height). The reason we did that is to control for the possibility that people who work more hours are larger because they may be moving less; the sibling’s hours of work are not taken into account so this just captures the causality of weight to hours of work (see columns 1 and 2 in Table 3, panels D and E), but that is not case for Black single men (see columns 3 and 4 in the study). As for Hispanics, we find no association between body weight and hours of work for either single men or single women. 

Alysse ElHage: The racial/ethnic differences in your findings, when it comes to BMI and hours of work, were quite interesting. For example, you found a positive association between BMI and hours of work for single Black and White men, as well as for Black and White women, but you did not find this at the married stage—except for White women. Why the difference here, particularly for White women compared to women of other races/ethnicities?  

Shoshana Grossbard: Previous literature suggests that the concept of beauty is culture dependent: it may be the case that thinness in women is a more desirable among Whites compared to Blacks or Hispanics. It may also be the case that given the tendency to marry within one’s race the marriage market circumstances of White women are more advantageous than those for Black or Hispanic women and married White women have more access to their husbands’ earnings, allowing them to work fewer hours.

Alysse ElHage: The second part of your study examined whether the relationship you found between BMI and hours worked is driven more by the labor market or marriage market. And for this part, you focused only on white women. First, define for us what you mean by “marriage market,” and what did you find among higher BMI married women in particular? 

Shoshana Grossbard: A marriage market is where people interested in marriage possibly meet. In the case of heterosexuals, these are marriageable men and women. It could include those who are already married and may possibly re-enter the marriage market. Demand and supply in these markets set prices for WIHO (or "work in the household") for the benefit of a spouse. 

Our results suggest that controlling for wages does not significantly change the association between BMI and hours worked, suggesting that the lower wage of high-BMI White women cannot explain the effect of BMI on hours of work. This leaves more chances that the explanation for the connection between BMI and hours of work is related to how BMI influences value in marriage markets.

Alysse ElHage: So higher BMI women who are married work more because they tend to marry down economically?

Shoshana Grossbard: Yes, that is one part of the story. For married White women, the coefficient of BMI is -0.112 (column 1), or in other words, a one-unit increase in wife’s BMI is associated with $1,120 reduction in annual husband income. Controlling for a spouse’s age and education has little effect on the estimate. The coefficient of BMI is not significant for married Black women regardless of the inclusion of age and education, and it is not significant for married Hispanic women when we include the husband’s age and education. This suggests that there is more of a material payoff for being thin in the case of White married women than in the case of Black or Hispanic married women. 

The other part of the story is even after accounting for lower income of their husbands, BMI has an additional effect on the work hours of White women. In other words, they receive a smaller share of their relatively low-income households. This suggests that high-BMI White women work more hours, not only because they are married to men earning less, but because they have less bargaining power in marriage, and can access less of their spouse’s income.

Alysse ElHage: For single White women, you sought to determine whether their expectation of marriage would impact their hours at work. Tell us what you found.

Shoshana Grossbard: We show that the positive association between BMI and hours of work of White single women increases with the self-assessed probability of future marriage and varies with expected cumulative spousal income. These findings reinforce the rational expectations interpretation according to which singles take future prospects of in-marriage transfers into account when determining their hours of work. The more likely singles were to marry, the more we found a positive connection between BMI and hours of work while single because we figure that the ones who are thinner are counting more on getting married and on getting more money from a spouse if they do.  

Editor's Note: To learn more about Dr. Grossbard's work, visit her website, econoflove.com, or follow her on Twitter @econoflove.