I was in pretty good shape in college, but I knew a couple of guys who struggled. My RA pilfered a plate from every all-you-can-eat establishment in the area. So Sunday was Godfather's Pizza, Monday may have been Wendy's salad bar, etc. He would just pack the plate in his backpack, go into the restaurant, hang out in the bathroom for a few minutes, then enjoy himself at the buffet. He literally had one for all 7 days of the week so he never paid for dinner. AFAIK he never got caught.
Another guy only got $50/month for ALL his expenses (excluding dorm costs of course). So he bummed a lot of food from us, i.e. we were about to throw out old food, he'd take it, etc.. We went to the grocery store for a pre-game cookout and they had London Broil for $2/lb, so I bought him a 5 lb steak. He ate the whole thing in one sitting.