Jonah Lehrer (of the Frontal Cortex, author of Proust Was a Neuroscientist) writes How the City Hurts Your Brain in the Boston Globe:
Related research has demonstrated that increased “cognitive load” — like the mental demands of being in a city — makes people more likely to choose chocolate cake instead of fruit salad, or indulge in a unhealthy snack. This is the one-two punch of city life: It subverts our ability to resist temptation even as it surrounds us with it, from fast-food outlets to fancy clothing stores. The end result is too many calories and too much credit card debt.
Don’t worry, there are benefits too.