The NY Times reported this week on a study that looked at the effects of New York City's requirement that chain restaurants post the calorie counts of each item on the menu. The researchers looked at fast food restaurants in high poverty neighborhoods, and compared purchases in New York and Newark. They found that the average purchase in New York was of more calories after the law was in effect than before, while there was no change in Newark.
The article offers a few hypotheses for why this might be the case. One possibility is that shoppers were more interested in a good value than in nutrition. I can testify that, at least for my husband, when we went to Nathans over the summer, the posted calorie counts encouraged him to buy a large drink rather than a small, because he could see that it was more than twice as much beverage for only a dollar more.
I would also suggest, from behavioral economics, that there is probably an anchoring effect from some of the really absurd things on the menu. About 1/3 of those who noticed the calorie signs said that they affected their purchases. Well, people do feel like they took nutrition into account when they pass up the 1,000 calorie triple megaburger with cheese and get the double burger instead.
Some of the people quoted in the article suggests that the calorie postings will have more effect over time. I'd be highly surprised if that were true. My guess is that over time, people will pay less and less attention to the signage.
I also think that the law has less impact because it only applies to chain restaurants. I don't think anyone is surprised to learn that Big Macs are bad for you. I think people would be more surprised by how many calories are in things that sound like they might be healthy. My sense is that most restaurants cook with far more butter and oil than almost anyone uses at home these days.