Breatharian , noun;
1. A person who believes it is possible to subsist healthily on air alone
1. Of or relating to a breatharian
This word is first attested in 1979 from breath + -arian, based on the form vegetarian, fruitarian, etc.
Breatharianism is rooted in Hinduism and yogic philosophy. The basic concept is that human beings can be sustained on prana alone. Prana is the vital life force in Hinduism, and one of the main sources of prana is the sun. According to breatharians, the energy in sunlight can be enough to keep the human body alive and well.
This is, of course, a very controversial practice and people have died attempting it.