Obesity Can Be Explained By Social Networks?
July 26th, 2007
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A a very interesting new study published in the New England Journal of Medicine claims that obesity is ”contagious” and can spread across contacts,
involved a detailed analysis of a large social network of 12,067 people who had been closely followed for 32 years, from 1971 until 2003. The investigators knew who was friends with whom, as well as who was a spouse or sibling or neighbor, and they knew how much each person weighed at various times over three decades. That let them examine what happened over the years as some individuals became obese. Did their friends also become obese? Did family members or neighbors?
The answer, the researchers report, was that people were most likely to become obese when a friend became obese. That increased a person’s chances of becoming obese by 57 percent.
[link]
The authors have used social network, a theory which treats an individual as sum of his contacts. Social networks have been used prominently in studying adolescent smoking; it is well know that most teen age smokers start smoking under peer pressure or follow the example of those perceived as leaders. In fact, a multi-million dollar intervention in Washington attempted to cut down the rates of teenage smoking by involving those students leaders in anti-smoking campaigns. Unfortunately, it failed.
Even in this study, the authors acknowledge that social networks can explain only so much; obesity has a strong genetic component. But why would obesity be influenced by peer group? Apart from the fact that an individual perceives obesity differently when he is surrounded by people of similar weight, he also attempts to restrict his friends to that particular group. Take smoking for an example. With increasing restriction on smoking in work places and even private homes, smokers are quite likely to have friends who smoke too. This restricts their networking ability and has been used to explain why smokers consistently makes less money than non-smokers.
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2 Responses to “Obesity Can Be Explained By Social Networks?”
Prashanth July 28th, 2007 at 3:08 pm #
I study Complex Networks, including social networks, in my research. I am curious as to how they concluded that friendship was the cause of obesity and not vice versa, i.e. that obese people are simply more likely to become friends. They had a time series of data for the BMIs of the people involved; this means that they had an EVOLVING network model, with people becoming obese over time (or becoming thin). I think if they correlate over the time dimension, they can get a better idea about the causality, and I don’t see that in their publication.
Rohit July 28th, 2007 at 10:32 pm #
Prashanth,
I agree. That’s a fair argument. While I am not an expert on social networks, I have seen research which shows that people are more likely to hang out with folks of their kind–as you pointed out that obese people might be hanging out with people with similar body weight as they would be more social acceptable.