Urban Obesity

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March 3, 2017 – MCAT CARS Passage

Question: What is your summary of the author’s main ideas. Post your own answer in the comments before reading those made by others.

We are not all equal when it comes to obesity. While genetics plays a role, the main causes of excess weight relate to the social environment. In the United States, researchers have long been aware that obesity levels in low-income groups are above average. The same is true in Europe and in the Swiss cities of Geneva and Lausanne, according to researchers in western Switzerland.

Doctors and geographers have pooled their expertise to create a body-mass index (BMI) map for the city of Lausanne. The map shows a clear correlation between low income and obesity: the working-class neighborhoods are overwhelmingly red (above-average BMI), while the middle-class suburbs are covered in blue (below-average BMI).

But this mapping exercise did not just confirm what was expected. In western Lausanne, the usual factors — education, income, age, health, ethnicity, gender and alcohol consumption — could not account for the residents’ extra weight. Something is missing, and the researchers have hypothesized that urban living itself could play a role. Their conclusions have been published in the British Medical Journal Open.

Thousands of residents hit the scales

More than 6,000 Lausanne residents volunteered to participate in the CoLaus study. In addition to carefully recording their BMI, the doctors also took down information on their state of health, income level and other social factors. The survey was run twice, six years apart, with the same people. The anonymous data then served as the basis for the study carried out jointly by EPFL geographers and epidemiologists from the Lausanne and Geneva university hospitals.

The researchers were able to prepare an accurate BMI map for the residents of Lausanne because they had the volunteers’ addresses. Blue and red dots were used to plot favorable and unfavorable BMI measurements, respectively. A number of clusters stood out, including a very sharp difference between the middle-class eastern part of the city and the working-class west.

It was at this point that the mapping approach produced an unexpected result. The geographers commonly apply a weighting method to corroborate their results. “We adjust the BMI readings for all the factors known to affect weight, including income, education level, age and some other factors,” said Stéphane Joost, a researcher at EPFL. “Once the values have been adjusted, the colored zones should disappear.”

Despite these adjustments, the map of western Lausanne remained red. The BMI readings of these residents defied the usual explanations. “This means that there are other factors we missed, or that their interaction is more complex than we thought.”

Identifying new causes in order to fight obesity

Urbanism is surely the key to a better understanding of the causes of obesity, according to Idris Guessous, co-author of the study and a medical doctor and epidemiologist at the Lausanne and Geneva university hospitals. “It appears that the urban environment has a major impact, independent of income and other common factors.” Is it a question of distance from green spaces, access to stores and fast-food restaurants, or geographical compartmentalization? For Guessous, these and other possible explanations need to be explored.

Guessous also mentions spatial dependence, a phenomenon that further intensifies differences between neighborhoods. “We tend to look and act like our neighbors, despite potentially sharp sociocultural differences.” Behavior is contagious. And among the behavioral traits in question, some have an impact on human health.

If the hypothesis is accurate and urbanism does play an important role in obesity, this could lead to news 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 ideas on how to improve disadvantaged neighborhoods.”

Adapted from sciencedaily

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This was an article on Population Health.

Have a great day.
Jack Westin
MCAT CARS Instructor.
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38 Comments


  1. City living is an independent risk factor for obesity

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  2. Urban-living= obesity role + imp. ^ understanding

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  3. Obesity can potentially be fixed by studying urbanization.

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  4. urban living = factor, obesity = complex

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  5. MIP: Obesity = low income + urbanism (Guessous)

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  6. Many factors play into the inequality of obesity , the major and more controllable one > Urban living

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  7. Obesity disproportionately affects those living in less affluent, urban neighborhoods. Interestingly, these differences still hold when adjusting for factors like income, age, and education. These findings suggest that some other factor is driving such discrepancies. Researchers believe that studying urban living itself, and how it differs from life in areas where obesity is present at more normal levels, could shed some light on the issue.

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  8. MI: Urbanism= major factor in obesity + more research needed

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  9. BMI mapping =/= only explanation for obesity; missing factor = urbanism + understanding it = finding solutions

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  10. Urban living = potentially new factor related to obesity (indep of income, etc) + need further investigation

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  11. Urbanism= obesity cause + unexpected
    Social environment affects obesity
    Low income correlates obesity

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  12. MI: Urbanism = new cause for obesity, further researcher needed

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  13. urbanization = obesity (RTA Idris)

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  14. studies show urbanism’s relationship with obesity

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  15. Urbanism may be important factor for obesity

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  16. Urbanism has a huge effect on obesity levels.

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  17. Social factors /=/ confirm obesity CW; uneed standing urban environment leads to new solutions RTA (G). Author neutral

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  18. obesity = low SE status, urbanism is key to understanding this relationship

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  19. Obesity is due to genetics + social environment -> low income, and especially urban living (spatial dependence behaviours)

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  20. obesity= attributed to not only individual and environmental factors, but also urban living

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  21. MI: low income + urban environment (gousseous) related to obesity

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  22. Obesity more social than genetic.
    Living in an urban area & low income – higher bmi
    Use surburbs as a model to create change

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  23. Obesity = urbanism, RTA (Guessous); other factors contribute

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  24. Mapping =/= confirm usual obesity factors; Urbanism could be the independent cause of obesity but needs further investigation

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  25. MIP: urb correlated to OB=unexpexted
    tone: neut

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  26. urbanization correlated w/ obesity

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  27. Low income groups = increased obesity levels. Urban environment = new obesity factor.

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  28. urban environment causes obesity due to reasons like of fast food, far from exercise facilities etc

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  29. BMI related to urbanism bec behavior=contagious—->lead to new methods of solving obesity

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  30. Income is not the only factor, but also the effect of urban environment when it comes to determining people’s BMI

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  31. Low-income -> increased obesity. Urbanism also plays a possible role in obesity which should be further explored.

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  32. MIP: Urban living could impact obesity
    Tone: Neutral

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  33. MIP: Mapping reveals BMI = complex ; Urbanized areas ~ higher obesity

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  34. MIP: urban living could be a factor; tone = neutral

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  35. MIP: obesity=corr urbanism; urban obesity missing factors=potential cure. tone: neutral.

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