Some obese people misperceive that their body size is normal and think they don't need to lose weight, according to research presented at the American Heart Association's Scientific Sessions 2009.
In the Dallas Heart Study of 5,893 people, researchers found that 8 percent of the 2,056 who were obese said they were satisfied with their body size or felt they could gain weight.
"Almost one in 10 obese individuals are satisfied with their body size and didn't perceive that they need to lose weight," said Tiffany Powell, M.D., lead author of the study and a cardiology fellow at the University of Texas Southwestern Medical Center in Dallas. "That is a sizeable percentage who don't understand they are overweight and believe they are healthy."
Participants included about 50 percent blacks, 20 percent Hispanics and 30 percent whites, similar to other urban populations, Powell said. About half - 54 percent - were women. African Americans (14 percent) and Hispanics (11 percent) were significantly more likely than whites (2 percent) to be satisfied with their body size and believe that they did not need to lose weight.
Using the sex-specific Stunkard nine-figure scale, participants chose the figure that represented their present body size and the figure that represented their ideal body size. Self-perceived ideal body size was classified as below normal, normal and above normal. Body size discrepancy, a measure of body size satisfaction, was calculated as the difference between self-perceived actual and self-perceived ideal body sizes.
Those with a misperception of body size believed they were healthy. But 35 percent of them had high blood pressure, 15 percent had high cholesterol, 14 percent had diabetes and 27 percent were current smokers. These risk factors are similar to obese individuals who acknowledged they had a weight problem and needed to lose weight, Powell said.
Overall, 2 percent to 3 percent of the study population perceived an above-normal body size as ideal. Compared to subjects who perceived their ideal body size as normal, those who perceived ideal body size to be above normal were more likely to be women, African American and had higher body mass index, blood pressure and higher insulin resistance.
Researchers also found:
- Those who misperceived their body size were less likely to go to a physician. In fact, 44 percent didn't visit a physician during the past year, compared to 26 percent of obese participants who correctly perceived they needed to lose weight.
- There was no significant difference between the two groups in socioeconomic status or access to health care due to insurance status.
- Among those who did see a physician in the past year, the obese individuals who did not feel they needed to lose weight were much less likely to report that their physician had told them they need to lose weight compared to those who perceived they needed to lose weight (38 percent vs 68 percent). Moreover, only 38 percent talked with their physician about dietary changes, while 64 percent of those with a more accurate body perception talked about changes.
- Obese people who were satisfied with their body size didn't exercise, while obese individuals who recognized they had a weight problem exercised regularly, on average.
The major limitation of the study is that researchers couldn't infer causality between associated beliefs and behaviors because the study is cross-sectional.
"This is an important population that we aren't seeing or targeting," Powell said. "Understanding and countering this misconception may be a novel and perhaps vitally important target for obesity prevention and treatment. Because many of these individuals believe they are healthier than they really are, they do not go to the doctor and thus community interventions will be needed. However, Powell also emphasized that her findings show that physicians need to talk with their obese patients about exercise and weight loss. "The onus falls on us as physicians to determine who this population is and how to talk with them."
Co-authors are Colby R. Ayers, M.S.; Michelle A. Albert, M.D., M.P.H.; Amit Khera, M.D., M.Sc.; Anand Rohatgi, M.D.; Jarett Berry, M.D., M.S.; Darren K. McGuire, M.D., M.H.Sc.; James A. de Lemos, M.D.; and Sandeep Das, M.D, M.P.H.
The study was funded by the Reynolds Foundation, which supports the Dallas Heart Study.
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