George Loewenstein, professor of Economic and Psycology at Carnegie Mellon University, authored an editorial in the American Journal of Clinical Nutrition entitled "Confronting reality: pitfalls of calorie posting" (AmJCN, apologies, but you can only read this article if you have a site-license via a library or university).
According to the editorial, mandatory restaurant labeling is more about politics than good science. The goal of the program is to reverse, or at least stop, the obesity epidemic by reducing calorie intake. New York was the first city in the U.S. to implement this policy, and did so based on one study published in 2008. However, this study showed only modest benefit and, by design, was unable to determine causality. This study could only generate a hypothesis. Since then, more rigorous studies have shown a modest benefit, failed to show a benefit, and even caused some harm - people ordered more calories.
A large proportion of people simply ignore the information. However, some people might actually choose to order more calories. Why? Given a limited amount of money to spend, some people appear to order as many calories as they can in order to get a "better deal." I would have to consult with my economist-in-training girlfriend to see if this is a sound explanation. But perhaps it fails because the premise is wrong - obesity is not simply the result of oblivious gluttony (see next blog post).
Regardless of the fundamental problem, namely that obesity is driven by the poor quality of the food and not merely the quantity, mandatory calorie postings in restaurants began with poor footing and they have not gained any since. The author remarks (with cynicism) that this policy may continue because it is better than the alternatives, such as taxing specific food items or reducing particular subsidies. This industry-favoring approach is echoed in the campaign sponsored by the Hershey (yes, the chocolate) Center for Health & Nutrition in collaboration with the American Dietetic Association named Moderation Nation. Hopefully the science will overcome the politics in this food fight.