Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Inedia
Hira Ratan Manek (born 12 September 1937) claims that since 18 June 1995 he has lived on water and occasionally tea, coffee, and buttermilk. Manek states that Sungazing is the key to his health citing yogis, ancient Egyptians, Aztecs, Mayans and Native Americans as practitioners of the art. While he and his proponents state that medical experts have confirmed his ability to draw sustenance by gazing at the sun, he was caught on camera eating a big meal in a San Francisco restaurant in the 2011 documentary "Eat the Sun".