I dunno: is this news?

Nicholas Christakis, a professor at Harvard Medical
School’s Department of Health Care Policy, said that socialising with
obese people affected a person’s perception of what constituted a
normal body weight.

“What we see here is that one person’s
obesity can influence numerous others to whom he or she is connected
both directly and indirectly,” he said. “In other words, it’s not that
obese or non-obese people simply find other similar people to hang out
with. Rather, there is a direct, causal relationship.”

He added: “The interpersonal, social network
effects we observe arise not because friends and siblings adopt each
other’s lifestyles. It’s more subtle than that. What appears to be
happening is that a person becoming obese most likely causes a change
of norms about what counts as an appropriate size.

People come to think that it is ok to be bigger since those around them are bigger, and this sensibility spreads.”

Well, in one sense it is because people are announcing it. But is it surprising in any way? I’d have thought that there were similar things going on in whether you’re tanned, or put highlights or gel in your hair, or wear tweed or pearls…all will be strongly influenced by what those around you do, won’t they? By what is the social norm in your milieu? Or accents perhaps?

The only thing that would slightly worry me about this finding is that it provides the externality (Hey, no, you being fat is not just about you, you’re making others fat as well!) as with "passive smoking" to allow the bansturbators to insist upon controlling your weight.

Points to the first person to spot this argument being made.