You’ve probably already read about this new study
that found that Obesity can spread from friend
According to the New York Times article:
The answer, the researchers report, was that people were most likely to become obese when a friend became obese. That increased a person’s chances of becoming obese by 57 percent. There was no effect when a neighbor gained or lost weight, however, and family members had less influence than friends.
It did not even matter if the friend was hundreds of miles away, the influence remained. And the greatest influence of all was between close mutual friends. There, if one became obese, the other had a 171 percent increased chance of becoming obese, too.
The same effect seemed to occur for weight loss, the investigators say. But since most people were gaining, not losing, over the 32 years, the result was, on average, that people grew fatter.
But how does obesity (or weight loss) spread
from person to person?
According to Dr. Nicholas Christakis (the lead
investigator for this study) there are at least
two potential mechanisms:
One possible mechanism is that I observe you and you begin to display certain behaviors that I then copy. For example, you might start running and then I might start running. Or you might invite me to go running with you. Or you might start eating certain fatty foods and I might start copying that behavior and eat fatty foods. Or you might take me with you to restaurants where I might eat fatty foods. What spreads from person to person is a behavior, and it is the behavior that we both might exhibit that then contributes to our changes in body size. So, the spread of behaviors from person to person might cause or underlie the spread of obesity.
A completely different mechanism would be for there to be not a spread of behaviors, but a spread of norms. I look at the people around me and they are gaining weight. This changes my idea, consciously or subconsciously, about what is an acceptable body size. People around me who start gaining weight reset my expectations about what it means to be overweight or thin, and this is what spreads from person to person: a norm. It is a kind of meme (but it is not quite a meme) that goes from person to person.
In our empirical work so far, we have found substantial evidence for the latter mechanism, the spread of norms, more than the spread of behaviors. It is a bit technical, but I will tell you why we have some evidence for norms. In our empirical work on obesity, we found two lines of suggestive evidence for a spread of norms. The first line of evidence caught everyone’s attention, and frankly it caught our attention when we noted it. It showed that it did not matter how far away your social contacts were; if they gained weight, it caused you to gain weight. This was the case whether your friend lived next door, ten miles away, 100 miles away, or 1000 miles away. Geographic distance did not mater to the obesity effect, the interpersonal effect.
what about TV and norms? Since most of the actors
and actresses, reporters, pundits and “real people”
on TV are very slim, shouldn’t TV be keeping us thin?
How can it be that there is a role of norms in the spread of obesity when the ideology in our society regarding thinness is the same as it ever was? The super models are just as thin as they ever were. Interestingly, there has been some change in the weight status of celebrities (there were always overweight celebrities, but I think there may be more now than there used to be); but super models are certainly as thin as they ever have been.
This is the difference between ideology and norms. People see these images of super models, but they might be less influenced by them than by the actions and appearance of the people immediately around them. For example, we see that people might behave badly and engage in criminal acts. We still have the ideology that the Bill of Rights holds and the Constitution holds and that there is goodness and there is evil. But people still behave badly when they are surrounded by people who behave badly. Again, it is the difference between norms and ideology, and this is how we square the circle in terms of why it is that there can be a spread of obesity, or an obesity epidemic, even though as a society we still seem to revere a different kind of body type from the one we are increasingly seeing.
Nevertheless, I did find this study quite encouraging.
If you give up TV (or severely curtail it), your
lifestyle change will have a positive effect on
those around you.
We also have found in our work that things beyond obesity and smoking cessation spread in networks. Happiness spreads in networks. If your friend’s friend becomes happy, it ripples through the network and can make you happy. We see clusters of happy and unhappy individuals in the social network like blinking lights in this complex fabric that is made up of people where some people are happy and some people are unhappy and there is a kind of gray zone between them. There is an ongoing kind of equilibrium that is reached in this social space. We have found that depression can spread, and drinking behaviors can spread, and the kinds of foods people choose to eat can spread…
So one person can make a difference!
Note: Dr. Nicholas Christakis, in the article,
mentions his brother Dimitri. I wonder if that
would be *the* Dr. Dimitri Christakis who has
done excellent research on the effects of TV
on children, and who has courageously come out
against young children (under two) watching
“New research shows that happiness isn’t just an individual
phenomenon; we can catch happiness from friends and family
members like an emotional virus. When just one person in a
group becomes happy, researchers were able to measure a
three-degree spread of that person’s cheer. In other words,
our moods can brighten thanks to someone we haven’t even met.”