A recent study from Lausanne’s EPFL published in the British Medical Journal Open shows that not all city addresses are equal when it comes to waistlines. Those living in west Lausanne are much more likely to be obese than those in the east. Even after controlling for differences in wealth, education, age and other factors, belt lengths differ. Not all of the extra pounds carried by people living in the working-class neighbourhoods of west Lausanne are wealth related. So what explains the remaining difference?

More than 6,000 Lausanne residents hoped onto the scales and answered detailed questions for the research team. Analysts then controlled the data for things that are normally associated with obesity like low education, low income, age, health, ethnicity, gender and alcohol consumption. Stripping out these factors was expected to remove all the red and blue on the map by accounting for all of the weight differences. It didn’t.

The map above shows areas with high obesity in red in traditionally working-class west Lausanne, and low obesity in blue in the middle class east of the city.

While researchers are not certain they think the remaining differences relate to contrasts in environment including who your neighbours are.

According to study co-author, Idris Guessous, “It appears that the urban environment has a major impact…” Possible explanations are proximity to green spaces, access to good food, density of fast-food restaurants and geographical compartmentalisation.

Guessous thinks your neighbours could have an impact on your waistline. “We tend to look and act like our neighbours, despite potentially sharp sociocultural differences.” He believes behaviour is contagious and that some of what we mimic has an impact on our weight.

If his hypothesis turns out to be true it could lead to news ways to address the obesity problem. “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,” he says. “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 neighbourhoods.”

More on this: 
Does urban living make us gain or lose weight? (EPFL website – in English)

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