Chance of becoming obese increases if friend is overweight, researchers say
Megan Ogilvie
Health Reporter

U.S. researchers have found that obesity can spread through a network of friends, just like the common cold or a penchant for a new style of jeans.

The study, released today in the New England Journal of Medicine, is the first to show that obesity is socially contagious and can spread from person to person to person.

After analyzing the health data collected from more than 12,000 people over 32 years, the researchers found a person’s chance of becoming obese increased by 57 per cent if someone they considered a friend became obese. That risk increased to 171 per cent if it was a mutual friend.

This is one of the first studies to use social networking science to examine behavioural health problems, said study co-author Nicholas Christakis, a physician and professor at Harvard Medical School.

“It’s very trendy to speak of the obesity epidemic,” he said. “We wanted to know if it is indeed an epidemic, whether there is a spread from person to person of a social contagion.”

The researchers also reported that the cascade effect is seen in up to three degrees of separation before it fizzles out and that friendship more strongly affects the spread of obesity than links between spouses, siblings or neighbours.

James Fowler, an assistant professor of political science at the University of California at San Diego and study co-author, said thinness is also contagious and that their study has shown social effects of obesity are as important as genes, gender and other known risk factors.

Experts say the findings will shed new light on how to combat the obesity epidemic. Roughly 60 per cent of Canadians are overweight.

Christakis said the cascade effect is more than just people with similar body size being attracted to one another.

“We found evidence that one person’s weight gain causes another person’s weight gain, that they actually influence each other.”

http://www.thestar.com/living/Health/article/239775