After New York City passed a law requir­ing many chain restau­rants to post the calorific value of all food they sold on their menus (in the same size and font as the price), researchers started look­ing at how the post­ing of calo­rie counts affect con­sumer deci­sion mak­ing and food con­sump­tion.

The study’s find­ings, as sum­marised rather con­cisely in The New York Times, show that the law didn’t have the desired effect the leg­is­la­tors undoubt­edly wanted:

It found that about half the cus­tomers noticed the calo­rie counts, which were promi­nently posted on menu boards. About 28 per­cent of those who noticed them said the infor­ma­tion had influ­enced their order­ing, and 9 out of 10 of those said they had made health­ier choices as a result.

But when the researchers checked receipts after­ward, they found that peo­ple had, in fact, ordered slightly more calo­ries than the typ­i­cal cus­tomer had before the label­ing law went into effect.

Freako­nom­ics author Stephen Dub­ner has his the­ory on the find­ings:

I sus­pect that the peo­ple who will be most respon­sive to it, espe­cially in the long run, are those who are already the most vig­i­lant about their health and well-being. Think of it this way: what if the safest dri­vers on the road were the only ones to wear seat belts?

I’m sub­scrib­ing instead to the the­ory I first dis­cov­ered after read­ing that the pres­ence of sal­ads on menus makes con­sumers more likely to eat unhealth­ily:

Once you see the salad, real­ize it’s bet­ter for you and know that it’s an option, your inner sense of self-satisfaction is trig­gered, and then… you let your­self order fries, just because you were oh-so-smart enough to think about the salad, if only fleetingly.