Availability of Fast Food Not an Indicator of High BMI

A total of 4,740 African Americans participated in a study to understand the link among the presence of a fast food restaurant nearby, food intake, body mass index (BMI) and waist size. “We observed no consistent associations between fast food restaurant availability and BMI or waist circumference.” People younger than 55 years consumed more food the closer the restaurants were, irrespective of their economic status. With proximity of a fast food restaurant, calorie intake increased more in men than in women.

It is accepted that availability of cheap and calorie-dense food promotes higher food consumption and increased risk of obesity. Proximity of such restaurants causes less  physical exercise, and provides easy to digest, not very nutritious, cheap food for low-income communities. There have, however, been no conclusive studies in this regard. In recent years, Americans have started eating out more often, and they mostly choose easy, tasty fast food. Mississippi has the highest number of obese people in America. High poverty levels and considerable presence of African Americans are known to be associated with the prevalence of obesity. This study analyzes data collected by the Jackson Heart Study carried out in Mississippi.

* For this study, 5,236 participants were geographically coded by neighborhood in the Jackson, Mississippi metropolitan statistical area. Each person’s body mass index and waist circumferences were measured. Their daily nutritional intake (fiber, fat, carbohydrates, etc.) was calculated.
* The number of fast food restaurants within circumferences of various radii around each neighborhood was determined.
* Each neighborhood was analyzed for demography, population density, advantages (education, marriage, employment, ownership) and disadvantages (incomplete education, poverty, single parenthood, unemployment), and was given a score.
* The data was analyzed in relation to distance from the number of fast food restaurants.

* Of the 4,740 participants in the sample, nearly one third were overweight and 52.6 percent were obese, with 10.1 percent classified as morbidly obese.
* Men and women younger than 55 and men older than 55 showed higher food consumption if the restaurants were closer.
* Fast food restaurant availability was higher in African-American neighborhoods than in white neighborhoods; higher in poor neighborhoods than in rich; higher in crowded than in less crowded localities.
* Body mass index and waist circumference were independent of proximity to restaurants, while fiber consumption went up with proximity to restaurants.

Shortcomings/Next steps
The study was carried out at a single time point. Effect of proximity to restaurants over a longer period of time on the BMI and body measurements needs to be examined. The study does not consider the portion sizes consumed, making it harder to calculate the overall energy consumption. The results are based on the patient set for a different study, making it non-random, and hence cannot be extrapolated to all populations.

More fast food restaurants are available in poorer, denser areas, with mostly African American residents than in well-to-do white areas. There is also a correlation between lower living standards and higher number of fast food restaurants. Higher availability means consumption of more food, but not an overall heavier weight or larger waist size. No clear evidence of restaurant-proximity related obesity was found. An unexpected positive effect of having restaurants close by was increased fiber intake in diet. Racially distinct neighborhoods may be a reason for concentration of certain businesses such as the fast food industry. Reducing segregation, restricting the number of such businesses and increasing licenses for supermarkets with healthy food products will help reduce such risks.

For More Information:
Associations of Fast Food Restaurant Availability With Dietary Intake andWeight Among African Americans in the Jackson Heart Study, 2000–2004
American Journal of Public Health, May 2011
By DeMarc A Hickson, PhD; Ana V Diez Roux, MD; Jackson State University/University of Mississippi, University of Michigan

*FYI Living Lab Reports Are Summaries of the Original Research.


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