Jump to content
Your browser is out of date. It has known security flaws and may not display all features of this websites. Learn how to update your browser[Close]

Obesity causes

Could urban living cause weight gain?

A study using the citizens of Lausanne to map excess weight around the city has defied all the usual explanations, suggesting that urbanism may be a key factor in obesity.

Researchers have long known that while genetics play a role, the main causes of excess weight have to do with the social environment - for example, obesity levels in low-income groups tend to be above average in the United States and Europe.

Doctors and geographers have produced a body-mass index (BMI) map for the western Swiss city of Lausanne that shows a clear correlation between low income and obesity: the working class neighbourhoods on the western side of the city are red (above average BMI), while middle-class suburbs are blue (below average BMI).

The study's BMI map for Lausanne (EPFL)

The study's BMI map for Lausanne


But the usual factors – education, income, age, health, ethnicity, gender and alcohol consumption – could not account for the western Lausanne residents’ extra weight, researchers say. 

This led them to hypothesize that urban living could be a factor, according to a joint statement by the Federal Institute of Technology Lausanne (EPFL), the Lausanne University Hospital (CHUV) and the Geneva University Hospital.

Their findings have been published in the British Medical Journal Open.

6,000 residents

More than 6,000 Lausanne residents volunteered to take part in the CoLaus study. The survey was run twice, six years apart, with the same people. This anonymous data was then used for the mapping study.

The geographers commonly use a weighting method to corroborate their results, so adjusting the BMI readings for all the factors known to affect weight, including income, education level, age and some other factors, explained Stéphane Joost, a researcher at EPFL. They were expecting the coloured zones to thus disappear.

But the map of western Switzerland remained red. “This means that there are other factors we missed, or that their interaction is more complex than we thought,” Joost said.

Urbanism could be key to a better understanding of the causes of obesity, believes doctor and epidemiologist Idris Guessous, who is the study’s co-author.

Fast food, less exercise?

Is it a question of distance from green spaces, access to stores and fastfood restaurants, or geographical compartmentalisation, wonders Guessous?  And what about spatial dependence, a phenomenon that further intensifies differences between neighborhoods? “We tend to look and act like our neighbours, despite potentially sharp sociocultural differences,” he said.

If urbanism does indeed play an important role in obesity, this could lead to new ways to address the 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,” said Guessous. “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 idea on how to improve disadvantaged neighbourhoods.”



All rights reserved. The content of the website by swissinfo.ch is copyrighted. It is intended for private use only. Any other use of the website content beyond the use stipulated above, particularly the distribution, modification, transmission, storage and copying requires prior written consent of swissinfo.ch. Should you be interested in any such use of the website content, please contact us via contact@swissinfo.ch.

As regards the use for private purposes, it is only permitted to use a hyperlink to specific content, and to place it on your own website or a website of third parties. The swissinfo.ch website content may only be embedded in an ad-free environment without any modifications. Specifically applying to all software, folders, data and their content provided for download by the swissinfo.ch website, a basic, non-exclusive and non-transferable license is granted that is restricted to the one-time downloading and saving of said data on private devices. All other rights remain the property of swissinfo.ch. In particular, any sale or commercial use of these data is prohibited.