Study: Friends, Family Members Influence Weight
Obesity is "socially contagious" and can be spread among friends or family members, likely because of altered perceptions of what is an acceptable body weight, according to a study published Thursday in the New England Journal of Medicine, the AP/Long Island Newsday reports (Chang, AP/Long Island Newsday, 7/26).
The study, led by Nicholas Christakis of Harvard Medical School and James Fowler of the University of California-San Diego, was the first to examine the role of social networks in a chronic condition.
The researchers analyzed 32 years of data on 12,067 people in three generations who participated in the Framingham Heart Study (Gellene, Los Angeles Times, 7/26).
The study found that when a person becomes obese, the likelihood that their closest friends will become obese in the next two to four years increases by 171%. The rates of increase are 57% among casual friends, 40% among siblings and 37% among spouses. The study found that same-sex friendships have a greater effect on an individual's likelihood of becoming obese than opposite-sex relationships.
According to the researchers, even close friends or siblings who live hundreds of miles apart can affect each other's weight. The study also found that when an individual loses weight, the likelihood of their friends and family members losing weight increases (Hellmich, USA Today, 7/26).
Christakis said, "It's almost a cliché to speak of the obesity epidemic as being an epidemic. But we wanted to see if it really did spread from person to person like a fashion or a germ" (Stein, Washington Post, 7/26).
Christakis added that the results do not suggest that friends of obese people gain weight because they eat similar foods but rather that they "look around them and see people gaining weight and then might change their attitudes of what constitutes an acceptable body size and might start to emulate those body sizes" (Smith, Richmond Times-Dispatch, 7/26).
He said people should not "break ties" with overweight friends because studies have shown friendships to be healthful, but he added that making friends with people who are "the proper weight" can be "beneficial" (Bhanoo, Baltimore Sun, 7/26).
Fowler said, "If we can get even a small number of obese people to lose weight, it might have a ripple effect, and we could contribute to reversing the epidemic" (USA Today, 7/26).
Richard Suzman, director of the National Institute on Aging's behavioral and social research program, called the study "one of the most exciting medical studies on medical sociology ... in decades" (Washington Post, 7/26). Suzman added, "This is a seminal study. It takes what was seen as a noninfectious disease and shows it clearly has got some communicable factors" (Los Angeles Times, 7/26).
However, Caroline Apovian, director of the Center for Nutrition and Weight Management at Boston Medical Center, said the study gives a "false perception" of the national obesity epidemic. Apovian added, "There are strong forces in this country that are moving us toward obesity, but I don't think social contagion is one of them." She named fast food and sedentary lifestyles as more relevant causes. "We idolize thinness," Apovian said, adding, "People are not running around being happy and obese" (Dembner, Boston Globe, 7/26).
Some expressed concern that the study will serve to further stigmatize obesity.
Louis Aronne, director of the Comprehensive Weight Control Program at the Weill Cornell Medical College, said, "There's a danger that people will be biased against the overweight even more than in the past. Is a mother going to say, 'I'm not going to let my kid play with an overweight kid because it's going to make my kid overweight'?" (Lite, New York Daily News, 7/26). An abstract of the study is available online.
Fowler will discuss the study's findings Thursday at 1 p.m. ET in a washingtonpost.com online chat. Questions can be submitted online. A transcript will be available online after the chat. In addition, four broadcast programs reported on the study. Summaries appear below.
- ABC News: Video of the segment and expanded ABC News coverage are available online (Johnson, ABCNews.com, 7/25).
- CBS' "Evening News": The segment includes comments from Fowler and Aronne (LaPook, "Evening News," CBS, 7/25). Video of the segment and expanded CBS news coverage are available online.
- NBC's "Nightly News": The segment includes comments from study author Christakis (Bazell, "Nightly News," NBC, 7/25). Video of the segment is available online.
- NPR's "Morning Edition": The segment includes comments from Fowler, Christakis and Kelly Brownell, an obesity researcher at Yale University (Aubrey, "Morning Edition," NPR, 7/26). Audio and a partial transcript of the segment are available online.