Restaurants in New York City are required to give customers nutritional information about menu items. Why? So that diners will have a better idea what they're eating, and maybe, just maybe, they'll become smarter eaters.
On her blog today, Megan McArdle points to a study that indicates the nutritional information doesn't make much of a difference:
There was never any very good evidence that labelling was going to work. Most of the arguments in support seemed to rely either on self reported data, or a gut check by a handful of already pretty slender bloggers—they were sure they'd pay attention to the calorie counts, and so why wouldn't everyone else? But personal hypotheticals are at best weak evidence, and self-report is even worse. This study found that a significant minority of people reported changing their behavior as a result of the calorie information, and ordering a lower-calorie meal. But when you looked at what they actually ordered, it was no less fattening than either logitudinal or latitudinal controls.