I don't do fast food places anymore after reading Fast Food Nation.
I can relate to your situation though. One semester I had several classes back to back, and 2 days a week had class from 8 till about 3 or 4.
I just packed a few lunches in a big lunch bag (the insulated kind), and carried it with me.
I'd be chowing down at the beginning of class sometimes, but oh well, better than living off that crap at fast food places.