Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
Inedia
Prahlad Jani is an Indian sadhu who says he has lived without food and water for more than 70 years. His claims were investigated by doctors at Sterling Hospital, Ahmedabad, Gujarat in 2003 and 2010. The study concluded that Prahlad Jani was able to survive under observation for two weeks without either food or water, and had passed no urine or stool, with no need for dialysis. Interviews with the researchers speak of strict observation and relate that round-the-clock observation was ensured by multiple CCTV cameras. Jani was subjected to multiple medical tests, and his only contact with any form of fluid was during bathing and gargling, with the fluid spat out measured by the doctors. The research team could not comment on his claim of having been able to survive in this way for decades.