at least at wisconsin badger games they do a general pat down on your pockets to make sure you aren't carrying things you can throw. they normally get you if you have like your camera, wallet and phone all in the same place and your pocket is bulging, if not, i don't think its a big deal. maybe bring a protein bar or something like that? just keep it well hidden so it doesn't get confiscated. don't see how you could do like protein powder or something because you wouldn't have anything to mix it in seeing as water bottles definitely aren't allowed into stadiums.