Jonah Lehrer reviews recent findings on “social contagion” and obesity:
It turns out that the habits of others shape our own, that we unconsciously regress to the dietary norms around us. Because we’re not particularly good at noticing when we’re sated and full – the stomach is a crude sensory organ – we rely on all sorts of external cues to tell us how much to eat. Many of these cues from other people, which is why our eating habits are so contagious.
This fits nicely with the experience of anyone who has spent time talking with an alcoholic about their drinking. They measure their drinking by their observations about others. “Everyone drinks like me!” “Most of my friends drink more than I do!” “I’ll quit if I ever get as bad as that guy!”