Metabolic water refers towater created inside a livingorganism throughmetabolism, byoxidizing energy-containing substances in food and adipose tissue. Animal metabolism produces about 107–110 grams of water per 100 grams offat,[1] 41–42 grams of water per 100 g ofprotein, and 60 grams of water per 100 g ofcarbohydrate.[2][1][3]
Some organisms, especiallyxerocoles — animals living in thedesert — rely exclusively on metabolic water. Migratorybirds must rely exclusively on metabolic water production while making non-stop flights, facilitated by the high metabolic rate during such flights.[4][5] Humans, by contrast, obtain only about 8–10% of their water needs through metabolic water production.[6]
Inmammals, the water produced from metabolism of protein roughly equals the amount needed to excrete theurea which is a byproduct of the metabolism of protein.[6] Birds, however, excreteuric acid and can have a net gain of water from the metabolism of protein.
