If we stopped eating and especially if we stopped drinking, our bodies would run out of energy and manifest life-threatening symptoms. We die and our consciousness leaves the body. Those who have clinically died and then returned to life tell of their out-of-body experiences, in which they saw their body lying lifeless while their consciousness hovered over it nearby.
They returned to life and became once again the individual personalities that came with their unique bodies, memories, and experiences. But they are never the same, for they are aware of this amazing quality of consciousness. It is tied to the body for a while and then it diffuses into the Universal Consciousness.
A person in a coma is not deemed to be conscious, though reports have shown that they respond to prayer. I have heard of comatose people who were ready to cross over to the Other Side and were held back by prayers from loved ones. The neuroscientist, Holley Alexander wrote an excellent book called Proof of Heaven about his own near death experience and coma. This is what he has to say:
"For me, it's become clear that the best way to look at it is to turn it around and realize that consciousness exists in a much richer form, free and independent of the brain, which has everything to do with the eternity of our souls and the fact that our awareness, our consciousness, our soul, our spirit, does not depend on the existence of the brain in the physical universe. In fact, it's freed up to a much richer knowing when we're outside."