I'm not a medical student yet, but when I was in high school, I took this Health Sciences class where I shadowed different areas of the hospital. My first two week placement was with a first year internal medicine resident (who I later found out lived in my neighborhood!). Anyways, every morning, when I'd come in, after greeting me, the first thing he would do was take out this tupperware filled with granola bars, apples, and rice crispy treats. Then he would tell me that I would have to take something before he begins showing me around. When things got boring or came to a standstill, he offered me food, lol.
I guess he values energetic students. He himself, nor his medical students he was responsible for, were never hungary and the morale seemed pretty high. Your superiors need to make sure you are satisfied physically and mentally, in order for you to learn. And I've seen medical students at other placements (including my volunteering) and they seem pretty drained, unlike the students I mentioned before.
Anyways, that was my experience with food and medical students, although very limited. I'd recommend obviously a hearty breakfast and as others mentioned before, having nourishments in your pocket, and maybe some candy (my teacher (a R.N. too) for that health sciences class told me it is good during surgery to combat passing out--although it seemed a little odd and far-fetched, but the reasoning makes sense (glucose or something need to be at a certain level to stay concious and prevent you from passing out, I dunno, I forget) ). Heck, if you don't pass out, suck on a jolly rancher
