There is no arguing that Americans are becoming more obese, and this trend is leading to severe health complications and massive healthcare spending. But what is causing our burgeoning obesity rates is an area of active debate. This is because weight gain is caused by the overall consumption of more calories than one expends, and there are many possible scenarios whereby this can happen. Some evidence suggests that blame should be focused on decreased physical activity, but findings from other studies point more to increased calorie consumption. Changes to our “food environment” – such as readily availability low-cost, high-calorie, nutrient-poor fast food – is often targeted as being an important driver of elevated consumption. If this is correct then it has important implications for decision makers regarding applications to open such establishments. Others suggest these poor food choices may be driven by lack of education and poverty.
To help understand the realities related to if, and how, the food environment influences body weight, Professor John Speakman (Institute of Genetics and Developmental Biology [IGDB], Chinese Academy of Sciences [CAS] and University of Aberdeen) and one of his students Mohsen Mazidi (IGDB) investigated the relationship between densities of full service and fast-food restaurants and prevalence of obesity across the United States. Their results, suggesting a lack of association, are published in detail in the August 2017 issue of
The American Journal of Clinical Nutrition (
DOI:10.3945/ajcn.116.151407 ).
Mazidi and Speakman hypothesized that, if restaurants are at least in part culpable in the obesity epidemic, one would predict that higher densities of them (per head of population) in a particular area would be associated with a greater prevalence of obesity in people who live there. Furthermore, if poverty and lack of education are related to obesity because less educated and poorer people eat out more at fast food locations, then they hypothesized that the statistical association between obesity and fast-food restaurant density would disappear when the mathematical equations are adjusted for % of a population living in poverty and the average level of education. To test these hypotheses, they utilized obesity prevalence data collected in 2012 by the US Centers for Disease Prevention and Control (CDC) and data related to fast-food and full-service restaurant density reported by the US Department of Agriculture’s Economic Research Service. They defined restaurant density as the number of establishments in a county per 1000 county residents.
Contrary to their hypotheses, they found in the raw data that the more restaurants (both fast-food and full-service) were in a county, the lower the obesity rates. This was principally because there were more restaurants in counties in which there were higher incomes and residents were more highly educated – characteristics that lower risk of obesity. In fact, when the equations were adjusted for income and education, any relationship between restaurant density and obesity disappeared.
The research team concluded that “variations in the densities of fast-food and full-service restaurants are not linked to the prevalence of obesity in the United States.” They suggest this is probably because on average only 15% of total calories are consumed in these establishments. They posit that their findings have implications for policy decisions regarding how we aim to tackle the obesity epidemic.
Contact:
Dr. John Speakman
