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The racial and ethnic composition of a community is associated with the obesity risk of individuals living within the community, according to a study led by researchers at the Agency for Healthcare Research and Quality (AHRQ) and the Johns Hopkins Bloomberg School of Public Health. The findings, published in the June 14 edition of the American Journal of Public Health, may help explain disparities in obesity rates among racial groups and point to some of the environmental factors that may contribute to obesity in the United States.

For the study, the researchers analyzed data from the Medical Expenditure Panel Survey, which represented a cross-section of the U.S. population. The data were matched with geographical information from the U.S. Census. Obesity was calculated based on each study participant's body mass index (BMI), a measure of weight in relation to height.

Analysis of the data found that community ethnic composition might affect residents' likelihood of being obese, and the effect varied by the residents' own ethnicity, for example, living in a community with a Hispanic population of 25 percent or greater was associated with 21 percent higher odds for obesity for Hispanics in that community. Non-Hispanic whites had 23 percent higher odds for obesity living in the same community.

The opposite was true for communities with high concentrations of non-Hispanic Asians. In those communities, the odds for obesity were 28 percent lower for non-Hispanic whites in those communities. While non-Hispanic blacks have the highest rates of obesity in U.S., living in a community with a high concentration of non-Hispanic blacks did not raise the odds of obesity even among non-Hispanic blacks.

"Obesity is one of the nation's most pressing health problems, and our findings suggest that community characteristics related to racial and ethnic composition may have an important effect on residents' weight," said James B. Kirby, PhD, of the Agency for Healthcare Research and Quality, who was the lead author of the study. "This study will enhance understanding of the disparities in the U.S. obesity epidemic and how certain racial and ethnic minorities are disproportionately affected."

"Social and built environments play an important role in influencing individuals' health outcomes including obesity. Future research needs to better understand the mechanisms, but clearly interventions are needed to reduce obesity disparities in the United States," said Youfa Wang, MD, PhD, MS, coauthor of the study and director of the Johns Hopkins Global Center on Childhood Obesity and Associate Professor at the Bloomberg School of Public Health.

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Johns Hopkins University Bloomberg School of Public Health: http://www.jhsph.edu