I read this quote 'Why were people so surprised when the New England Journal of Medicine reported that obesity is a contagion you catch from your friends?' and truly felt the need to research this topic further. Some friends cause hypertension, some cause inebriation and some, it is now confirmed, cause obesity. Or the opposite. After all, food and drink are the ampersands that unite so many of us: it's how Ben found Jerry, how Mike met Ike, why Baskin embraced Robbins.
If your friend, or even your friend’s friend is obese, you are 57 percent more likely to be obese. Wow that is some study! Happily, that isn't yet the case. For while the study can explain some friendships--it doesn't account for so many of history's finest partnerships: Laurel & Hardy, Skipper & Gilligan, Abbott & Costello, Siskel & Ebert, and those most enduring of all buddies, Ernie & Bert.
Not everyone agrees with the study's findings. Some scienticists say that maybe fat or happy people like to hang out together because in general, we like to be around people who are like us, so it might just be correlaton (or association), not causation. Also, it could be the environment that causes friends to get fat at the same time. Maybe they all live to close to a McDonalds that just opened up. One counter study found that if a high school student was tall, his or her friends were more likely to be tall. You can't catch height from someone else.
The studies used a "looser" mathematical model (not sure what that means here). But they also found that if person A considered person B a friend but not vice-versa, if person B got fat, then it increased the chance of person A getting fat. But if person A got fat it did not affect the chances of person B getting fat. So if something in the environment caused one person to get fat (like a new McDonalds), it should affect both people. But it did not always do so. That means there has to be another reason. Maybe what you do is affected by what you think other people think is okay.