Are fighters only permitted to drink water in between rounds? When Tennis players have their breaks, you seem them have a munch of an energy bar or an energy jelly to keep them going - assume this is not allowed in Boxing otherwise surely you'd see fighters doing this in the late rounds especially?
They're not drinking only water. Have some stuff there to juice up the water with important basics. Eating during a fight is not very smart though.
Are you asking about for amateur boxing? I can't stand drinking anything but plain water. I once had Gatorade between and it gets all glued to the top of my mouth and back of my throat. It was horrible. I don't think there is time for a sandwich. Only time to catch your breath.