Ram Dass(Richard Alpert) talks about this Indian guy whose total input for fifteen years was two glasses of milk. He had lots of energy, slept two hours a night, and weighed 90 pounds. He was in exellent shape.
"All you have got to do is find one guy who is doing it, and it makes a shambles of of the whole trip. The relation of mind to matter is so much more exquisite, and the only way man is able to play with these games is when he has extricated his awareness from his thinking and sensing. Then his awareness becomes just like a laser beam, and it develops a kind of power that is capable of things we do not attribute as possible to human beings. For that power to be developed, however, Buddha points out you must extract yourself from attachment. That is a very tricky concept- what it means to be free of attachment. In the same way you watch your senses, you watch your eyes see and you watch the desires being manifested, but you no longer identify with your own desires"
"There are many very, very clear documented instances in India of a being who is buried alive for a period of time and after a year or two is brought back and they come out of the state of trance they have been in, and there they are- and they were put in an airproof box. One of them when asked, "well, how did you breath?" said, "my cells had enough oxygen to keep my brain and my heart muscle alive, and that was all that was necessary". They had put him in the earth in a box, and there were some ants, and the ants had eaten away part of his arm. He had been in this trance, see......... So where are human drives, let alone our social motives? I mean, do you not need air and food? I mean, after all, we assume those are all necessary."
If these anecdotes are true, there is much we do not know about health.