Obesity is one of the most concerning epidemics in developed societies, particularly in North America, where it has become an important public health issue affecting nearly one third of all Americans. A number of risk factors have been identified over the years, in addition to inactivity and a high calorie diet. An interesting finding in a recent study in the New England Journal of Medicine shows that obesity may be socially contagious.
The study conducted by Christakis and Fowler from the Department of Health Care Policy, Harvard Medical School, Boston, examined the spread of obesity (defined as BMI > 30) over a large social network. They looked at a social network of 12,067 people who were assessed repeatedly from 1971 to 2003 as part of the Framingham Heart Study. The study postulated that the presence of obese social contacts can influence one’s behavior related to eating and exercising habits, as well as affect one’s tolerance to obesity.
The study also observed that, among mutual friends, if one friend becomes obese over a given period of time, the other friend’s chances of becoming obese increased by almost 171%. Also, among adult siblings, if one sibling becomes obese, the other’s risk of becoming obese increased by 40%. If one spouse becomes obese, the likelihood of the partner becoming obese increased by 37%. The effect was not geographically contained, and even friends hundreds of miles away experienced the same phenomenon. Even friends of friends continued to have this influence until the degree of separation was greater than 4 people.
These effects were not seen among neighbors, indicating that a greater degree of social interaction is required. Christakis and Fowler also examined whether this gain in weight could be related to smoking-cessation among these social contacts, and found that the spread of smoking-cessation could not account for the spread of obesity in the network.
This study highlights the importance of environmental factors in contributing to the obesity problem. Such information can be utilized to battle the epidemic of obesity. A number of studies in the past have shown that alcohol and smoking-cessation programs and weight loss interventions that provide peer support are more successful than programs lacking such support. If one’s obesity can promote tolerance of the problem in a friend, the corollary might be that pursuing fitness and a healthy diet might influence one’s friends to adopt similar habits in their lives.
Unfortunately, gaining weight is easier than losing it. Emulating an obese or overweight friend is a lot easier than emulating a friend with a trimmer form, and it is likely that an overweight friend would exert more influence on one’s weight than a slim friend.
One can make the most of this discovery by thinking outside of traditional weight-loss strategies. Rather than simply devising a traditional diet and exercise regime, diet and exercise programs should include the individual’s close friends. While group exercise programs would probably be the best in terms of peer support, even individual programs may enjoy more success if one knows that his or her friends are on the same program. By including friends in a healthy diet plan, people could also gain new sources of recipes and ideas. Collaborating with friends and peers may bring us one step closer to keeping the obesity epidemic in check, as well as keeping our own waist lines trim.
References
1. Christakis NA, Fowler JH. The spread of obesity in a large social network over 32 years. N Engl J Med. 2007 Jul 26;357(4):370-9.
2. Wing RR, Jeffery RW. Benefits of recruiting participants with friends and increasing social support for weight loss and maintenance. J Consult Clin Psychol. Feb 1999;67(1):132-138.
3. Malchodi CS, Oncken C, Dornelas EA, Caramanica L, Gregonis E, Curry SL. The effects of peer counseling on smoking cessation and reduction. Obstet Gynecol. 2003 Mar;101(3):504-10.
4. Montgomery GH, Erblich J, DiLorenzo R, Bovbjerg DH. Family and friends with disease: their impact on perceived risk. Prev Med. 2003 Sep;37(3):242-249.
