Fast food is a hallmark of modern living, and while it may be convenient, it's not doing us any favors.
A new study from Penn State, West Virginia and Michigan State universities suggests it's one of several factors contributing to a decline in American life expectancy.
The research, published this week in the journal Social Science & Medicine, found that people living in communities with more fast-food restaurants are living shorter lives. Another major factor found to negatively impact life expectancy was the number of people in a community with jobs in the extraction industry, which includes mining, quarrying and natural gas production. A third key factor was a community's population density, with people living in rural areas having a longevity edge over those in more urban environments. In this case, more people is not necessarily merrier.
Life expectancy — defined as the length of time a person born in a specific year can expect to live — is one of the most critical ways to gauge a society's overall health. But, after making steady gains over the previous decades, American life expectancy flat-lined in 2014 — and then began reversing. From 2014 to 2017, the average years in an American life rolled back from 78.9 to 78.6 years.
"American life expectancy recently declined for the first time in decades, and we wanted to explore the factors contributing to this decline," lead author Elizabeth Dobis of the Penn State-based Northeast Regional Center for Rural Development explained in a press release. "Because of regional variation in life expectancy, we knew community-level factors must matter."
For the study, the team looked at how life expectancy in 2014 has changed from a 1980 baseline on a county-by-county basis. They ended up combing through data from more than 3,000 counties — enough to build a comprehensive statistical model that weighed the impact of 12 community variables. They were also able to control for personal variables that are already established as factors on lifespan, including sex, race, education and alcohol use.
"By analyzing place-based factors alongside personal factors, we were able to draw several conclusions about which community characteristics contribute most strongly to this variation in life expectancy."
Their findings? People who lived near fast-food restaurants are having time shaved from their lives.
But that factor wasn't the only thief of time. People who worked in "extraction industries" — i.e. mining and oil and gas extraction — were also dying younger than those who did not. The population density of a community also had an adverse impact on lifespan. Indeed, the researchers found people living in less dense, rural communities lived longer lives, on average.
It seems at least a few of the reasons why people move to the city — conveniences, jobs, and simply to be around more people — are also bad for their health.
How bad, exactly?
"For example, for every one percentage point increase in the number of fast-food restaurants in a county, life expectancy declined by .004 years for men and .006 years for women."
Expanding on that grim arithmetic, for each 10 percentage point increase in the number of fast-food restaurants took a 15- to 20-day hit on life expectancy. Researchers found a similar relationship between oil and gas jobs and how long people lived.
"Another interesting finding was that lower population density, or living in more rural areas, is associated with higher life expectancy," study co-author Stephan Goetz adds. "This suggests that living in large, densely-settled metropolitan areas, with all of their amenities and other advantages, comes at the expense of lower life expectancy, at least in a statistical sense."
One thing that stood out to researchers, regardless of a community's density, was how strongly people living there acted like an actual community. Factors like access to doctors and how well people supported each other were seen as having a positive impact on life expectancy.