Obesity is Contagious, and so is Junk Science

TCS Daily has a good piece on the recent study 'proving' that obesity is contagious. The experimenters examined the Body Mass Index data of a particular group of people over time, saw some nice correlations, so instantly jumped to the conclusion that fatness spreads through people who know each other.

By what causal mechanism you say? Apparently 'social contagion' means if your friends are fat, so will be you, because you emulate their lifestyle. Unfortunately what the study 'proved' are really just some interesting hypotheses that need some real testing. Unfortunately all that the media (rightly so) seizes on is the bottom-line.

And here's a joke for all the physicists out there. The study 'proved' that having fat friends makes you more fat. It also found that the distance of friends from each other didn't matter.

'The jump from association to cause may be most evident in the conclusion drawn by the researchers with regard to the association of weight gain in friends living far from each other. "We were stunned to find that people who were hundreds of miles away had just as much impact on a person's weight status as friends who are next door."'

Now that, my friends, is spooky action at a distance.