"This study found that males who persistently experienced high levels of discrimination during a nine-year period were more likely to see their waist circumference increase by an inch compared to those who did not report discrimination," said Haslyn E.R. Hunte, an assistant professor of health and kinesiology. "Females who reported similar experiences also saw their waistlines grow by more than half an inch. This shows how discrimination hurts people physically, and it's a reminder how people's unfair treatment of others can be very powerful.
"People who feel unfairly treated should be aware of this connection between the stress related to their perception and consider coping strategies like exercise or other healthy behaviors as a coping mechanism for such stress. More importantly, as a society we must become more aware of how we treat people and that treating others unfairly matters beyond hurt feelings."
These findings are published online in the American Journal of Epidemiology. The study, based on a predominantly white sample of more than 1,400 people, compared health and aging data from the 1995 and 2004 National Survey of Midlife Development in the United States. Hunte found that people who reported recurring discrimination tended to have a higher increase in waist circumference over time. Men reported an average of 2.39 centimeters increase in waist circumference compared to those who reported low levels of discrimination, and women reported an average increase of 1.88 centimeters over others during the nine-year period.
"While this study shows there is a difference between men and women, it doesn't provide specific reasons for that difference," Hunte said. "More research will need to be done to understand how and why men and women cope differently with this stress or if there are differences in how their bodies react."
Hunte focused on waist circumference - instead of the body mass index formula, which measures obesity based on height and weight - because abdominal fat is a better indicator of poor cardiovascular-related health outcomes than body mass index.
"Being fat is not healthy, but there are greater problems with individuals who are more pear shaped, meaning that fat builds up in their waist region, rather than someone whose fat is deposited throughout the body," Hunte said. "There is some indication that stressors, such as interpersonal discrimination, can concentrate fat around the midsection. We're not sure why, and more work needs to be done to understand this connection between behavior and physiology. How does what's above the skin affect what is taking place under the skin"
People who reported ongoing perceptions of discrimination said they were treated with less courtesy than others, received poorer customer service or people acted as if they were afraid of them. The source of discrimination is not known, but Hunte did exempt individuals who reported that they felt discrimination due to their weight.
Hunte is planning to investigate this further by studying biomarkers, such as cortisol, which is a stress-induced hormone, in relationship to effects of discrimination.
Hunte was supported by the Department of Health and Kinesiology and the Robert Wood Johnson Foundation Health and Society Scholars program. The national survey was funded by National Institute of Aging and the John D. Catherine T. MacArthur Foundation Research Network on Successful Midlife Development.