The discrimination that obese people feel, whether it is poor service at a restaurant or being treated differently in the workplace, may have a direct impact on their physical health, according to new research from Purdue University.

"Obesity is a physiological issue, but when people have negative interactions in their social world - including a sense of being discriminated against - it can make matters worse and contribute to a person's declining physical health," said Markus H. Schafer, the doctoral student in sociology and gerontology who led the study. "We found that around a third of the severely obese people in the United States report facing some form of discriminatory experience, and the experience of weight discrimination plays into people's own perspective about their weight. It seems that many people are internalizing the prejudice and stigma they feel, and it contributes to stress, which ultimately affects their health."

Overweight and obesity are measured by the body mass index scale, which accounts for height, weight and gender. The Centers for Disease Control and Prevention report that 34 percent of U.S. adults are overweight and another 34 percent are obese. Being overweight is a predisposition for obesity, which puts people at risk for cancers, heart disease, diabetes and other complications and quality of life issues.

The Purdue team's findings are published in this month's Social Psychology Quarterly journal. Schafer, along with Kenneth F. Ferraro, a distinguished professor of sociology, compared body mass indexes to people's health and perceptions of weight discrimination. More than 1,500 people, ages 25-74, were surveyed in 1995 and 2005 about issues related to aging and health equality as part of the National Survey of Midlife Development in the United States.

"As expected, those who were obese fared worse in overall health when they were followed up with 10 years later," Schafer said. "But we found there was a difference among those who felt they were discriminated against and those who didn't."

About 11 percent of those who were moderately obese and 33 percent of those who were severely obese reported weight discrimination, and these were the individuals who had the sharpest decline over time in their functional abilities, such as the capacity to climb stairs or carry everyday items. Functional ability is a key measure for health status, Schafer said.

"We've seen considerable progress to address racial and gender discrimination in the United States, but the iceberg of weight discrimination still receives relatively little attention," said Ferraro, who studies obesity and aging. "This is an interesting paradox because as the rates of obesity rise in this country, one might expect that anti-fat prejudice would decline. Public health campaigns for weight control are needed, but the stigma that many obese persons experience also exacts a toll on health."

Schafer and Ferraro are affiliated with the Department of Sociology and the Center on Aging and the Life Course. Schafer, who will be an assistant professor of sociology at the University of Toronto this fall, is currently studying social relationships and health among retirement community residents. Ferraro, who is director of the Center on Aging and the Life Course, is continuing to work on obesity issues related to aging.