I'll say this up front... I love hackathons (and similar events: ICFP programming contest). I have fun hanging out with a bunch of like minded people, and I find that I learn a ton when I force myself to sit down and actually make something. I can certainly see the points about food/drink, however, the events I've been to (and hosted a bit of) did have healthy options. I think there would be a mass lynching if there weren't unhealthy options too, but ah well, caveat emptor.
However! I actually don't think that occasional hackathons (everything in moderation) is harmful to hacker culture. People do not model their lives around hackathons. As a participant, I can tell you that I do not want to feel that crappy on a regular basis under any circumstances. Rather, hackathons are a reflection of a culture that already exists. Fix the culture, not the results, because I'm sure that lack of good sleep, diet, and exercise are far more pervasive and prevelant problems outside of hackathons.