But new research from Stanford University health economists adds another wrinkle to understanding these pay differentials: obese workers are paid less only when they have employer-sponsored health insurance.

These findings, just published in a working paper on the Web site of the National Bureau of Economic Research, suggest that employers-recognizing that obese workers are likely to have higher medical costs-compensate with lower pay for them. Given that employment-based health insurance requires that employees in the same plan make the same contributions to premiums, the employers adjust wages to account for the greater expense for obese workers' health care, according to the paper.

"A self-correcting mechanism is at work in the labor market," explained study co-author Kate Bundorf, MPH, PhD, assistant professor of health research and policy at Stanford and a fellow at the university's Center for Health Policy/Center for Primary Care and Outcomes Research. The study doesn't address whether the wage disparity is fair, she noted; it simply demonstrates that there are strong economic incentives for employers to adjust for the varying costs of providing medical benefits to different types of workers. "Our findings reinforce that these market forces are powerful," she said.

The findings also shed light on the question of who bears the cost of obesity-related health care. While it is often assumed that obese workers' medical expenses are passed on to their employers and normal-weight co-workers, the Stanford study indicates that obese workers are paying for it themselves through lower wages.

Understanding who bears the cost of obesity-related medical expenses has become more pressing, with a significant
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Contact: Sara Selis
650-723-0759
Stanford University Medical Center
9-May-2005