One of the things I do in a situation like that is to make some pasta and stick it in a tupperware container. It will keep well enough, not a lot of sugar or very simple carbs.
Clint's idea about a small protein shake or something similar is a good thought too. Depends on your stomach, how you handle different foods. I almost have to have some protein or fat to stay in my stomach, but every person is different.
Good luck buddy. Make a thread in the Grappling forum and let us know how you do.
14-4 Sig Bets