Will Posting Calories on Fast Food Menus Reduce Obesity?

I mentioned a while back that the recently passed health care legislation will require fast food restaurants to post calorie counts for menu items, including the combo meals. I speculated that there may be some menu tweaking that goes on before the law goes into effect to bring down some of the shockingly high calories contents. 

Andrew Sullivan drew my attention to a piece by Ryan Sager that isn't so optimistic about the efficacy of such a law. Among other things he mentions a study done of similar rules implemented in New York City;

In a study ofStarbucks patrons in New York City, over the course of a year before and after the implementation of calorie labeling, researchers from Stanford University found a slight decrease in how many calories customers purchased — 6% per transaction. There were, however, three important caveats: 1) the reductions were almost entirely in food ordered (drinks were unaffected); 2) the reductions were greater for patrons from high-income and high-education zip codes, and 3) the reductions disappeared entirely around the holidays.

A comment on Sullivan's in response to Sager's skepticism caught my attention, especially because it references research done regarding Washington State's food labeling laws;

I work in the Research Support office of a children's hospital research institute, and I have seen the literature testing Washington (State)'s menu laws.  As a result of research being done here, the menu laws do not significantly impact a person's ordering when they are ordering for themselves.  However, when parents are ordering for, or supervising the ordering of, their children, the parents will significantly cut the calories and fat intake of their children.  Additionally, places like California Pizza Company and Cheesecake Factory, have reduced portion sizes and the use of fat- and salt-heavy dressings in their salads as a result of menu labeling.  Anecdotal but indicative.

I'm also intrigued by Ta Nehesi Coates' comments regarding shame and obesity from last month;

I'm not clear on precisely how much shame can actually help. It's shame that's created our absurd McWeightLoss culture where Octomom takes to the cover of celebrity magazines to show off her new bikini body, and retired athletes claim to have found the secret to losing five pounds a week. It's symptomatic of who we are, of our abiding belief in short-cuts, and our technological ability to elide truth. The truth is that weight loss--like almost anything really worth doing--is long, hard and very lonely. It requires you to live in a way that many of your friends and family almost certainly do not.

Rod Dreher at Beliefnet also chimed in last month on the topic of obesity here and here

Anyone have any thoughs?