Birds have figured it out: “Animal metabolism produces about 110 grams of water per 100 grams of fat,[1] 42 grams of water per 100 g of protein and 60 grams of

Birds have figured it out: “Animal metabolism produces about 110 grams of water per 100 grams of fat,[1] 42 grams of water per 100 g of protein and 60 grams of water per 100 g of carbohydrate. [...] In mammals, the water produced from metabolism of protein roughly equals the amount needed to excrete the urea which is a byproduct of the metabolism of protein.[6] Birds, however, excrete uric acid and can have a net gain of water from the metabolism of protein.“ https://en.m.wikipedia.org/wiki/Metabolic_water https://en.m.wikipedia.org/wiki/Metabolic_water