No heat transfer from the body in any of my setups. However, the first few sips from the hose after a time are warm due to the sun heating up the water exposed in the hose. Once past those initial two sips, my water is plenty cool for me, even after a long hike in the heat. I don't pack ice in the bladder, but you certainly could. Most bladders have a wide mouth (Nalgene bottle threads, usually).