Social Networks and Obesity

It has been known for years that the likelihood of being overweight increases among family members,in part to a combination of sharing the same gene pool and living together.
Social Networks and Obesity

Likewise, spouses tend to gain weight together. However, the New England Journal of Medicine published a groundbreaking study that revealed social relationships have an even more powerful impact on weight gain.1

Surprising Findings
The association of obesity among friends, spouses, siblings and neighbors over a 32-year period was evaluated in more than 12,000 people from the Framingham Heart Study. The researchers found that friends had the greatest impact on obesity and that the type of friendship made a difference. For example, a close, mutual friendship resulted in a 171-percent increased risk of obesity while a one-way friendship increased the chances by 57 percent. These findings contrast with a 40-percent increased risk among siblings and 37 percent between spouses. Friendships are so influential, in fact, that the likelihood of obesity even increased when the friend of a friend was the one to gain weight. Same gender relationships also have a stronger influence than those between genders. Perhaps most surprising was the finding that geographical closeness made no difference.

While this study established strong links between social relationships and obesity, the authors state the opposite is just as likely to happen. An unrelated study showed that when people joined a group-based weight-loss program with friends and family, they lost more weight and kept if off better than those who joined the same program alone.2

Additionally, according to a study on an online, team-based weight loss and physical activity program, teammates lost similar amounts of weight and their weight loss was highly affected by social influence.3

Weight Watchers Fosters Social Networks
The Weight Watchers approach involves learning how to have a healthy lifestyle by making wise food choices and moving more. But that's not all. A supportive atmosphere is equally important. (Find out more in Science and Weight Watchers). Weight Watchers encourages the development of social relationships with other people who are also working to achieve and maintain a healthy weight.

It is likely that the wider the social network, the greater the influence. Indeed, it has been established in a study that people assigned to attend Weight Watchers meetings and use eTools lost 50 percent more weight on average during a 6 month period than those who were instructed to only attend meetings.4 So just as your weight gain has likely been influenced by relationships you've had in the past, you have the opportunity to be influenced toward weight loss by establishing relationships with like-minded people, and you, in turn, can be a healthy-weight influence on your overweight friends and family.


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1 Christakis NA, Fowler JH. The spread of obesity in a large social network over 32 years. The New England Journal of Medicine. 2007 July; 357(4): 370-379.

2 Wing RR, Jeffery RW. Benefits of recruiting participants with friends and increasing social support for weight loss and maintenance. J Consult Clin Psychol. 1999 Feb; 67(1) 132-138.

3 Leahey TM, Kumar R, Weinberg BM, Wing RR. Teammates and social influence affect weight loss outcomes in a team-based weight loss competition. Obesity (Silver Spring). 2012 Jul;20(7):1413-8.

4 Nguyen V et al. Obesity 15 (9S) A221, 2007