I've seen "Fat Head," but I found it focused too much on bashing "Supersize Me" rather than explaining/advocating the right thing to do, and why. One book I've read recently that talks a lot about this is "Why We Get Fat" which is a sort of abridged version of "Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health" both by Taubes. Definitely check them out if you're interested. I've applied the reasoning in these books personally with great success, so there's my anecdotal evidence :)