There's a term for that: "hangry" (hungry-angry). I know it well... seems to afflict introverted people more. For me, at least, I get very absorbed in projects and interests... so I forget to eat, and then I am suddenly a little fuzzy around the edges.

Conferences without food pretty much suck, as far as I am concerned. I have gone to some very expensive events and then there has been cheap pre-fab food... like those awful sandwiches they sell on airlines. OR there was good food, but it was $40 more per meal, after already paying $500 for a weekend? If you're going to ask $500, at least don't come with extra expenses!