The study, by researchers at the University of Texas MD Anderson Cancer Center, found a particularly strong association among those with a lower income.
"According to prior research, African-Americans, particularly women, have higher rates of obesity than other ethnic groups, and the gap is growing," said Lorraine Reitzel, an assistant professor in the Department of Health Disparities Research at MD Anderson who led the study published online in the American Journal of Public Health.
"The results of this study add to the literature indicating that a person's neighborhood environment and the foods that they're exposed to can contribute to a higher BMI."
For the study, Reitzel and colleagues tracked the health records of more than 1,400 black adult Houston residents. The team logged the participants’ body mass indexes and the proximity and density of fast food restaurants in their neighborhoods. The study participants were also broken into two income groups: those making less than $40,000 a year and those making $40,000 or more a year.
In addition, researchers examined other factors that influence a person's weight, including gender, age, physical activity, individual household income, median neighborhood income, education, partner status, employment status, residential tenure, activity levels, and family dynamics.
The results showed the greater the density of fast-food places, the higher a resident's BMI. There was no significant association between a higher BMI and living more than five miles away from a fast-food restaurant.
"We found a significant relationship between the number of fast food restaurants and BMI for within a half-mile, one-mile, and two-miles of the home, but only among lower-income study participants," said Reitzel.
"There's something about living close to a fast food restaurant that's associated with a higher BMI. Fast food is specifically designed to be affordable, appealing, and convenient. People are pressed for time, and they behave in such a way that will cost them the least amount of time to get things done, and this may extend to their food choices."
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Reitzel said the findings offer clues to why lower-income residents and blacks may face greater risks associated with obesity including diabetes, cancer, and heart disease.
"We need to find the relationships and triggers that relate to this population's BMI, as they're at the greatest risk for becoming obese and developing associated health problems," said Reitzel. "Such information can help inform policies and interventions to prevent health disparities."
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