NY Times ran a column studying how posted calories affect food orders in fast food restaurants. Two studies were commented on, to conflicting conclusions. One study said there was no effect, and the other study saw some change in the way people ordered.
What does this all mean? To me, it says that calorie information alone is a poor way to determine a healthy diet. Not because monitoring calories is, in and of itself a bad thing, but because I still think that the average person doesn't understand the complex nature of caloric intake and output. Numerous studies have shown that people overeat when presented with lower calorie snacks. The idea is that they believe the food is healthier for them, so they can afford to indulge more than normal, and then end up over indulging.
The fact is, dieting is a complex process. Any one factor isn't enough to determine good health. You need to balance what you eat. A healthy diet is one in which you get enough vitamins, minerals, proteins, fiber, and fat. Counting calories is an oversimplification. It doesn't account for the other benefits you might receive from a particular food.
I find it especially unhelpful to do so in fast food restaurants. Fast food evolved from an occasional indulgance to a staple meal in the American household for a variety of reasons, not the least of which is that it's a full meal for very little money. The cost of healthy ingredients is rising, but people's paychecks are not. Worrying about the calorie count of a given item is a luxury that many in this country can't afford.
I've seen this with soup kitchens as well. As much as we try to give our clients at GCN access to fruit and vegetables, most of the time, the meals are starch based. Why? Because grains and tubers are cheap. Rice costs less than vegetables. And it's more filling. It's a high calorie, starchy meal, to make you feel fuller for longer, provided in the least expensive manner.
Until healthy food is made affordable and accessible, and until people see the benefit in cooking for themselves, placing calorie listings on fast food is like trying to take a bath with your clothes one. It might seem like a good idea, but it doesn't really accomplish much in the long run.