Obesity as contagion

Here are some clips from a rather fascinating article by Kolata in the NYTimes. We know that moods are like viruses, contagious - one happy person can lift the mood of the group they are in, one depressed person can do the opposite. Such a process appears to operate on a much longer time scale with respect to body mass. (By the way, I draft this post on Wednesday afternoon and later at happy hour at Genna's bar on Capitol square in Madison, I look up at the NBC evening news to find the material featured there. The marketing of sexy new findings moves very fast).

The Framingham study 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....Proximity did not seem to matter: the influence of the friend remained even if the friend was hundreds of miles away. And the greatest influence of all was between mutual close friends. There, if one became obese, the odds of the other becoming obese were nearly tripled...You change your idea of what is an acceptable body type by looking at the people around you.