In the ER there is no "lunch break". It's usually "eat on the run" so I bring lots of finger foods: baby carrots and cut up fruit. I'll make a peanut butter sandwich and cut it into 4 parts and stick it in a baggie. If I bring something that has to be heated up then it's guaranteed to be so busy that I end up snacking on crap because I don't have the time to heat my food.