The Body is composed of 50-75% of water, depending on age and body fatness. Water is essential for living, significantly more so than food. Death will usually occur after one week without any liquids (2 to 3 days in the heat) but humans have been known to survive some months without food.
The common rate of sweat loss is about 275ml in the heat. Prolonged Exercise performance can be impaired by depletion of the body's energy stores and by disturbances of water and electrolyte balance. Exercise can exceed two liters per hour in highly fit and well-acclimatized athletes.
