Some may already be feeling the weight of the infamous freshman (or sophomore, or junior) fifteen halfway through first semester. Unlimited options at the dining hall, late-night munchies and weekend partying can all accumulate as another roll below the belt, but some new research suggests students might have something to blame other than the pile of cheesy, greasy fried goodness that is the BU Platter — specifically, the friends devouring it with them.
A recent study shows that it may no longer be coincidence that friends are able to walk into each other’s closets and find something that fits: researchers Nicholas Christakis and James Fowler have added obesity to the long list of items friends often share.
“You start gaining weight, and I adjust my expectations of what a normal body is,” said Dr. Christakis, physician and professor of medical sociology at Harvard Medical School.
Christakis and co-author James Fowler, associate professor of political science at University of California at San Diego, published their study The Spread of Obesity in a Large Social Network over 32 Years in The New England Journal of Medicine this summer. They examined the Framingham Heart Study, a comprehensive health study of a large community since 1948, to examine the effect of peer relationships and obesity.
FAT CHANCE OF FRIENDSHIP
The researchers found a person had a 57 percent increased chance of becoming obese if a close friend became obese. Same sex friendship pairs influenced these chances more strongly, Fowler said.
Distance between friends had no effect on obesity rates. Friends living “100 miles away [were] just as influential [as] living next door,” according to Fowler.
The study found that obesity could not only spread through friends, but people were 40 percent more likely to become obese if a sibling did and 37 percent more likely if a spouse gained weight, Fowler said.
According to the study, Christakis and Fowler performed a quantitative analysis of the nature and the extent of social networks as a possible contributor to the obesity epidemic. Though Christakis and Fowler admit they did not directly study the reasons for this relationship, they said their work “sheds light on social mechanisms.” They conjectured that shared behaviors and social norms about body image are to blame for the spread of obesity.
“There is some hint in our findings that it may be more the latter norms than behaviors,” Christakis said.
OVERWEIGHT OBSERVATIONS
Christakis and Fowler studied the social networks established in the Framingham Heart Study, a study of over 12,000 participants and their social relationships over 32 years-from 1971 to 2003. The Framingham Heart Study provided Christakis and Fowler with each participants’ body-mass index. They, then, used longitudinal statistical models to examine whether weight gain has a contagious effect on social networks.
The unique structure of the Framingham Heart Study enabled researchers to not only analyze weight gain, but also examine the entire social community. Christakis said college students are a population researchers need to study further.
“Other people are beginning to think about college students,” Christakis said. “Tattooing and piercing can spread from person to person in college students. Why shouldn’t other health behaviors spread?”
Using the evidence from the 32-year study, Christakis and Fowler were able to analyze obesity over three decades of friendships, break-ups and neighborhoods. As waistlines added inches, who was still friends with whom five, ten, even twenty years down the road?
“We had to spend over half a million dollars to re-extract certain data that had not previously been used,” Christakis said. “This data set is one of very few that contains longitudinal information about network ties.”
PALS PACK ON THE POUNDS TOGETHER
The word is out: one friends’ weight can affect another’s. Should individuals choose friends based on what the scale reads?
“You should not dump your fat friends; you should hold onto them for dear life,” Fowler said. “[The] support of an extra person makes you less likely to overeat, more likely to exercise. If you drop a friend who becomes obese, it increases your chances of becoming obese.”
Christakis said weight should not be a factor in friend selection.
“I think people should choose their friends based on the people they feel simpatico with,” he said.
College of Communication senior Liz Miles agrees-she too does not think body weight should determine the end of a friendship.
“If you like that person enough, you should remain friends with them,” she said. “Just be cautious of your own habits.”
Miles said that what friends do when they are together can certainly reflect similarities in body size. She suggests friends participate in group exercise as a healthy alternative to offset the social dining we Americans love.
“I think [obesity] has a lot to do with how lazy we are as a nation,” Miles said.
Associate Professor of Medicine and Pediatrics at BU School of Medicine Caroline Apovian said she does not believe obesity can be spread through friends.
“I really don’t agree with that,” said Apovian of the study’s finding that obesity is contagious within social networks. “I think the research was good research, but I don’t think it was interpreted correctly.”
She said obesity among friends is attributed to shared interests and then making friends with each other because of specific behaviors.
“They’re not catching [obesity] from each other,” she said. “They’re just happening to be there doing the same thing and they’re becoming friends.
“People who go to the gym a lot have friends who like to exercise too,” she said. “Why would you have a friend who sits and drinks beer while you do triathlons?”
According to Apovian, who is also the director of Nutrition and Weight Management Center at Boston Medical Center, individuals on a weight-loss kick may have to reconsider who their friends are.
“You’re going to have to be careful who you hang out with if you want to change your lifestyle,” she said. “If you decide you’re going to lose weight, you probably can’t hang out with your obese friends because they’re going to want to go out to eat.”
People most likely pick friends based on their own habits, Apovian said.
“First you are obese, then find friends who are obese,” she said. “Then you hang out with them. They’re not out there running marathons and doing triathlons.”
Apovian said she thinks obesity in college students needs to be studied separately because of the “freshman 10, sophomore 20, and junior 30.”
“People on the track team are not going to hang out with people who are gaining weight,” she said. “Jocks hang out with each other, nerds hang out with each other, and I think the people who gain the weight hang out with each other. I don’t think they necessarily catch the weight from each other.”
HEAVY HITTER
Since publication of the obesity report, hundreds of newspapers and thousands of blogs have both praised and criticized the results, Christakis said.
“We never expected the kind of attention that it got,” he said.
Fowler and Christakis received “fan mail and hate mail,” including letters, emails, and phone calls. For the most part, scholars supported the study, according to the co-authors.
“I think since we are social creatures, it does make sense that if people are closely connected in a relationship that their health behaviors would impact the others,” said Assistant Director of Boston University’s Sargent College Nutrition and Fitness Center Alison Books. “This study shows support for that phenomenon.”
Books said lifestyle behaviors influence friends.
“If someone is connected to a group of people who eat a certain way or live their life a certain way, it is likely to become how a person lives, too,” said Books. “If all of your friends are fit and healthy, you’re going to participate in certain activities that help you stay fit and healthy. If your friends are not active, I think it’s a lot harder to rise above that social norm, even if it’s going to benefit your health.”
The way to reverse the obesity epidemic is to support friends, according to Books.
“Social support is really important, and I think that’s what this study points to,” she said. “We need to help each other.”
The researchers found that, just as obesity can be spread through friends, weight loss can also be contagious.
“All of our effects are symmetrical,” Christakis said.
Christakis said his research is “the foundation for the field of public health.”
“[The study] takes seriously the intention that human beings are imbedded in social networks and this imbeddedness is relevant to their lives,” Christakis said. “People are interconnected so their health is interconnected.