Steve Sailer is doing a good job pointing out how useless economists have been, so why not pile on. I got this idea awhile ago and simply looked around various universities' econ department faculty pictures, and I have a fairly good but not certain impression that economists are fatter than similar academics, for example psychologists on the one hand and physicists and engineers on the other. Their close academic peers tend toward the average or ectomorphic side, whereas they definitely have an above-average BMI. It's hard not to notice because most highly educated, professional people are in the normal-to-thin range.
No links provided, as I don't recall every last department I looked at for the economists and physicists, etc., but half the fun here is taking a look around for yourself.
I could care less what these guys look like per se, but it says something deeper about them. Everyone else in their social stratum is thin or average, so they're clearly more likely to let themselves go, probably more so with sugars (desserts) and starches (bowls of pasta). I think this is caused by their greater delight in rationalizing destructive behavior, whether individual or social -- they're endlessly in search of those intellectual bonus points for being counter-intuitive. Bunch of grade-grubbing dorks.
I doubt that it has to do with the discipline itself, like if you transplanted an ectomorphic physicist or mathematician into an econ department, he wouldn't blimp out after absorbing their ideas. It's more like people who wish to rationalize destructive behavior sort themselves into econ departments. Why did they settle on econ? Who knows, it could have been completely random a hundred or so years ago, if the other social sciences had already been seeded by people with a moral outlook. Sociologists also encourage socially destructive behavior, but it's always out of some higher conviction that it's the right thing to do, rather than an amoral rationalization. Or there could be something inherently attractive about econ to such people.