City Living, No Matter Your Class Level, Can Make You Obese

City living
Living in a city may be why you can't lose any weight. Jason Murphy CC BY 2.0

Though some consider obesity to be a matter of genetics, there are other factors at play — eating too much sugar and too many carbs is neither good for your health nor your waistline. Now, Swiss doctors and geographers have teamed up to investigate another potential risk factor: your neighborhood.

To do this, the research team created a body mass index (BMI) map for the Swiss city of Lausanne by using volunteered data from more than 6,000 residents. Though BMI is not always the best measure of fat, researchers relied on the method to at least try and find a clear correlation between income and obesity. While they found a correlation, one that’s been suspected for a while now, they also found living in a city may fuel obesity, even among those who are well off.

Why the focus on money? Researchers cited an increasing number of studies suggest "neighborhood socioeconomic context can be measured by neighborhood deprivation, neighborhood segregation, or population density — all of which can predict the development of obesity and other related health outcomes.

Researchers brought in Lausanne residents for BMI measurements twice over the course of five years. They then used the resident’s addresses to curate their map, featuring a number of colored "zones" to represent BMI; blue dots represented below-average BMI and red dots represented above-average BMI. They found middle-class suburbs were predominantly blue, while the working-class parts of the city were mainly red.

"We adjust the BMI readings for all the factors known to affect weight, including income, education level, age, and some other factors," Stéphane Joost, a researcher at EPFL university in Lausanne, said in a press release . "Once the values have been adjusted, the colored zones should disappear." However, after adjusting the values, Joost and her colleagues found the colored zones didn’t disappear. In the western part of Lausanne — which features many Mediterranean migrant workers — people still carried around extra weight, even in the most affluent areas .

Co-author of the study Idris Guessous, a medical doctor and epidemiologist, suggests the lack of parks or easy access to fast food could explain persistent, above-average BMIs in more affluent parts of the city. Guessous believes it could also be spatial dependence, which is when "[w]e tend to look and act like our neighbors, despite potentially sharp sociocultural differences," he said.

The researchers say their hypothesis needs to be tested on a larger scale, but as is, it could lead to a change in how we address the way city life can affect our health.

"You cannot change your age, it's not easy to act on your educational level, and equal income for all is the stuff of utopia," Guessous said. "But we can do something about city living. Once we've gained a better understanding of the role of urbanism, we'll be able to look at the more affluent suburbs and get ideas on how to improve disadvantaged neighborhoods."

Source: Joost S, et al. Persistent spatial clusters of high body mass index in a Swiss urban population as revealed by the 5-year GeoCoLaus longitudinal study. BMJ. 2016.

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