People who work longer hours are more likely to be obese. Time to invest in a standing desk?

IN THE last year we have written a series of articles on working hours, many of which were rather popular. We have tried to explain why the rich now work longer than the poor, and why working shorter hours is good for your productivity. What about the effect of working hours on your weight? A new paper, written by Joelle Abramowitz, an economist at the US Census Bureau, has some startling results. She starts out by showing a simple graph. Those who work longer tend to be bigger (see chart).

That graph is interesting, but doesn’t quite cut the mustard. After all, there may be other factors at play that mean that hardworking people tend to be overweight—one may not cause the other. Workaholic bankers who can afford to entertain clients in Michelin-starred restaurants are prone to pile on the pounds. So Ms Abramowitz uses regressions, which allows her to control for a variety of other factors, like income. Her results have a few surprises: those with a college degree are likely to be slimmer. Rather depressingly, marriage results in women getting thinner, but men fatter.

She shows that for workers in "non-strenuous" jobs—things like secretarial work and accountancy—ten additional hours spent working per week are associated with an increase in body-mass index of 0.4 for women and 0.2 for men. That translates, on average, into an increase of 2.5 pounds and 1.4 pounds respectively. Unsurprisingly, for those whose jobs require a bit of physical exertion, the effect no longer holds.

So why do long hours result in weight gain? Only 20% of American jobs are even mildly strenuous, compared to 50% in 1960. In 1960 a tenth of the American workforce was involved in agriculture, but today it's more like 1%. More time at the desk means less movement. Busy people may have less time to prepare good meals, instead choosing a take-away. (Management consultants, in my experience at least, tend to be rather knowledgeable about fancy restaurants near them that also deliver). They exercise less. And workaholics sleep less: inadequate shut-eye is associated with weight gain.

Women gain more weight than men, Ms Abramowitz reasons, because they tend to substitute work for health-improving activities like exercise. Men are pretty sedentary, whether or not they work long hours.

So maybe desk-jobbers should include a bit of physicality in the daily grind. Standing up while working—as we talked about last year—is one option.