Body size misperception: A novel determinant in the obesity epidemic

By LaKisha Ladson / Feb. 12-18, 2011

Some people who are obese and at increased risk for factors that could lead to heart disease don’t realize they need to lose weight, researchers at UT Southwestern have found.

When asked, 8 percent of more than 2,000 obese people studied said they were at the weight they wanted to be or that they wanted to get larger. The trial participants were part of the Dallas Heart Study, a groundbreaking investigation of cardiovascular disease that first involved more than 6,100 Dallas County residents.

Dr. Tiffany Powell

“For physicians, this can help us better reach our patients,” said Dr. Tiffany Powell, a cardiology fellow at UT Southwestern and lead author of the research letter published in the Archives of Internal Medicine. “We may tell patients to diet and exercise, but they may not be ready to hear that. If they think they’re OK, our advice may go in one ear and out the other.”

Researchers also found that these same people had similar cardiovascular disease risk factors as obese individuals who recognize that they need to lose weight. Those with body-size misperception, however, believed they were at lower risk for hypertension, diabetes and high cholesterol.

“It’s not the presence of misperception by itself that is dangerous,” Dr. Powell said. “It’s the company that misperception keeps that makes this a potentially important barrier to losing weight.”

Dr. Powell said because the participants with body-size misperception aren’t seeing a physician regularly, community-based interventions — where lifestyle changes are promoted in churches or other community settings — may be a solution.

The next step will be to determine long-term cardiovascular outcomes of people with body-size misperception, Dr. Powell said.

The research was funded by the National Institutes of Health, the American College of Cardiology Foundation/GE Healthcare Career Development Award and the Donald W. Reynolds Foundation.


A Matter of Misperception

At risk: People who are obese, defined as having a body mass index of 30 or greater. Previous research has shown that obesity is related to higher risk of heart attack and stroke. Individuals involved in this study with body-size misperception were less likely to see a physician regularly, to exercise, to receive counseling about lifestyle changes for weight loss, or to be aware of the prevalence of high blood pressure and diabetes — all of which increase the risk for heart disease.

Discovery: When asked, 8 percent of more than 2,000 obese people studied said they were at the weight they wanted to be or that they wanted to get larger. Among African-Americans and Hispanics, that surprising statistic rose — 14 percent and 11 percent, respectively.

Methodology: The 2,056 obese participants enrolled in the Dallas Heart Study from July 2000 to January 2002 were shown a standard figure-rating scale that represented body sizes from very thin to very obese. They were asked to choose one figure that represented them and one of the size they wanted to look like. Participants with body-size misperception chose ideal body sizes the same or larger than their body size. Participants also were asked about specific health beliefs and practices. Researchers then compared those results to responses from obese participants without body misperception.

Investigators involved: UT Southwestern researchers involved in the study are Dr. Powell; Dr. James de Lemos, associate professor of internal medicine; Dr. Kamakki Banks, postdoctoral researcher in internal medicine; Colby Ayers, biostatistical consultant; Dr. Anand Rohatgi, assistant professor of internal medicine; Dr. Amit Khera, assistant professor of internal medicine; Dr. Darren McGuire, associate professor of internal medicine; Dr. Jarett Berry, assistant professor of internal medicine; Dr. Gloria Vega, professor of clinical nutrition; Dr. Scott Grundy, director of the Center for Human Nutrition and chairman of clinical nutrition; and Dr. Sandeep Das, assistant professor of internal medicine. Dr. Michelle Albert of Harvard Medical School and Brigham and Women’s Hospital also participated.