Obesity Spreads “Like Wildfire” Through Social Networks

Virtually every newspaper in America is all over the New England Journal of Medicine report that obesity spreads, virus-like, through networks of friends and loved ones. The Washington Post, for example, reports that a Harvard Medical School study that followed 12,000 people over 32 years, found that "social networks" play
a surprisingly powerful role in determining an individual’s chances of
gaining weight, transmitting an increased risk of becoming obese from
wives to husbands, from brothers to brothers and from friends to
friends. The paper reports that researchers found that when one spouse became obese, the other
was 37 percent more likely to do so in the next two to four years,
compared to other couples. If a man became obese, his brother’s risk
rose by 40 percent. Surprisingly, the risk rose even more sharply among friends
— between 57 and 171 percent, depending on whether they considered
each other mutual friends.
Nicholas A. Christakis of Harvard Medical School, who led the study, told the Post: "What spreads is an idea. As people around you gain weight, your
attitudes about what constitutes an acceptable body size changes, and
you might follow suit and emulate that body size. It
may cross some kind of threshold, and you can see an epidemic take off.
Once it starts, it’s hard to stop it. It can spread like wildfire."
Read more in the Washington Post.