Originally published Nov. 27, 2017 at Saporta Report Thought Leadership
By Charles Courtemanche
From 1971 to 2014, the childhood obesity rate in the U.S. rose from 5 percent to 17 percent.
This trend has become a major public health concern because obese children often become obese adults, which increases the odds of a variety of conditions such as heart disease, diabetes and stroke.
Another striking trend that occurred alongside the rise in childhood obesity was the increasing number of dual-income households with children. Looking at data from Current Population Surveys by the U.S. Department of Labor, between 1970 and 2013, the labor force participation rate increased from 42 percent to 70 percent among mothers and only slightly declined among fathers, from 97 percent to 93 percent.
The concurrent nature of these trends has led researchers to ask whether a causal connection is possible. As parents increase their work hours, children are more likely to be unsupervised or supervised in group settings, which can lead to less healthy eating or more sedentary activity. When parents have less time available to prepare food, it can lead to a greater reliance on less healthy restaurant meals or pre-prepared processed foods.
In a paper recently released by the National Bureau of Economic Research, Rusty Tchernis, Xilin Zhou and I examined the effect of parents’ work hours on children’s weight. We used data from the National Longitudinal Survey of Youth, which has tracked nearly 13,000 individuals for almost 40 years, beginning when they were young adults. The dataset also includes information on respondents’ children, which provides a unique opportunity to link parents’ labor market activities to children’s health outcomes.
Previous studies have documented a small positive relationship between parents’ work and childhood obesity. Our study’s primary innovation is to push beyond correlations and attempt to identify the causal effect of parents’ work hours on children’s weight.
Dual-income families differ from those in which only one parent works or no parents work in numerous ways that are difficult for researchers to measure, making separating correlation from causality difficult.
We aimed to identify the causal effect by leveraging “as-good-as-random” variation that comes from the tendency for both mothers and fathers to increase their work hours when their youngest child reaches school age. Tracking subsequent changes in weight among older children in the household allows for an estimation of the causal effect of the increase in parental work.
Using this strategy, we found that greater parental work hours lead to large increases in children’s body mass index (BMI) and probabilities of being overweight and obese. The results imply that the increase in parents’ labor force participation accounts for more than 10 percent of the concurrent rise in childhood obesity. We found no evidence that mothers’ and fathers’ work hours affect children’s weight differently. We also found that the effect of parental work hours on children’s weight is concentrated among advantaged households, as measured by an index reflecting parents’ education, race and the mother’s marital status.
The implication of these results is not that parents should avoid working or that the rise in maternal employment has been a net negative for society. Rather, we see the results as fitting into the broader narrative of obesity being a byproduct of otherwise-welfare-enhancing technological and societal progress.
More research is needed into exactly why parental work hours contribute to childhood obesity and which policy interventions might help blunt this adverse effect while retaining the benefits of increased labor force participation.
Charles Courtemanche is an associate professor of economics in the Andrew Young School of Policy Studies at Georgia State University, with research interests into health economics, including obesity, health insurance coverage and big-box retailers.