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Is Obesity Contagious? July 26, 2007

Posted by Mrs Weird Scientist in Easy As Pie, Human Body, Nutrition and Health, Psychology and Behavior.

A new study in the New England Journal of Medicine is suggesting that the people you like can affect your chances of becoming obese. In fact, having an obese friend could make you 57 percent more likely to also become obese. The closer the friend, the stronger the effect. The results seem to show that obesity is socially contagious. Even more interesting is that if friends of your friends gained weight, this effect could still ripple out to you.

Scale Here’s What Researchers Did

Nicholas Christakis, a professor of sociology at Harvard University, joined up with James Fowler of the University of California. Together, they analyzed 32 years of records for 12,067 people and they found clusters of obesity among friends. What if obese people are already that way and are just drawn to one another though? Well, this wasn’t the case. The researchers also found that if two people considered one another friends-it meant that if one gained weight, the other was 171 percent more likely to become obese. If only one person considered the other a friend, then the obesity was only likely to spread to the person who held that view. Basically, the people we like and consider friends are ones who we end up mimicking when it comes to bad habits.

It Doesn’t Matter Where You Live

Now this study result is one I found really interesting. If a person had an obese neighbor, it didn’t affect whether they would be obese. On the other hand, if they had an obese friend who lived far away, this still meant they were more likely to pack on the pounds.


Habits Get Passed On

The researchers theorize that this effect occurs because us humans tend to mimic our friends. We may not realize we’re doing it, so it’s subconcious, but we still pick up their poor habits. These poor habits will be anything from eating to exercise and other lifestyle habits. With obesity rising in Canada, the United States and Great Britain (among other places!), it’s really important that researchers look at these kinds of patterns, so we can figure out how to help people tackle obesity.

Grab A Friend And Your Walking Shoes

This study confirmed something that makes perfect sense. Groups such as Weight Watchers have had success, in part, because of the social networking aspect. By obtaining support from others who are also trying to lose weight and adopt healthy eating habits, they tend to be more successful in achieving their goals. With a little teamwork, the two people in the picture above can hopefully make some healthy lifestyle changes!

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1. Russ Farris - August 1, 2007

The Christakis-Fowler hypothesis says that obesity is spread through social ties. Obesity is contagious, but you don’t catch it by watching your friends eat too much. You catch it the same way you catch a cold–by inhaling or ingesting certain germs.
In our book, The Potbelly Syndrome, Dr. Per Mårin and I show how chronic infections cause obesity, type 2 diabetes, and heart disease. We believe that The Potbelly Syndrome gives a more plausible explanation for the spread of obesity. Thanks.
Russell Farris

2. Miss Weird Scientist - August 1, 2007

Hi Russell,

To be honest, your theory is interesting but when you used the word ’cause,’ you lost a lot of credibility. I don’t see the studies and evidence (including widespread academic acceptance) to indicate a link that warrants your use of the word ’cause.’ You don’t show sufficient enough evidence to make your statement valid. I think that this recent study by Christakis is more academically sound in comparison with your theory. I’m not even saying that it’s the only link! Good grief, no! Hehe. Obesity is far too complex to try to pinpoint a single cause-most people will agree that it’s a complicated interplay of many factors. The social aspect is merely one of those factors. I’m not saying your theory has no merit either-certainly, I see the logic in your proposed link between chronic infections and obesity but the way you have presented the information is questionable.

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