Our Friends' Weight Influences Our Weight Gain and Loss

Click here to listen to this podcast

People who hang out with friends heavier than they are tend to gain weight. Those who socialize with leaner friends tend to maintain their weight, or even lose a few pounds.

But why?

Is it that friends influence our behavior? Or do we simply tend to have friends that resemble ourselves—the birds of a feather flock together effect.

To find out, researchers looked at students from two high schools. One school is rural and mostly white. The other is urban, with a racially mixed student body. The researchers analyzed the students’ body mass and social networks.

They found that overweight students who had lean friends had a 40 percent chance of dropping weight within a year, versus only a 27 percent chance of gaining weight during that time. But if borderline obese students had obese friends there was a 56 percent chance that they’d gain weight during the year, and only a 15 percent chance they’d drop some pounds. The finding is in the journal Public Library of Science ONE.

The researchers conclude that social influence is indeed a big factor in weight loss and gain. Because you’re not what you eat—you’re who you eat with.  

—Christie Nicholson

[The above text is a transcript of this podcast.]

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.