Hydrated body burns more fat, less protein
In a somewhat older study researchers raised liquid levels in their test subjects and measured the effect on their metabolism. The subjects burned more fat and less proteins. It sounds impossible, but water is anabolic.
The researchers dehydrated their test subjects by giving them a salt solution. The salt drew the water out of their cells. The researchers imitated the effect of a high liquid level by introducing water, and used a hormone to reduce the amount of liquid lost through the urine.
Below you can see the effect of liquid on the release of fats from the fat cells, so that the body can burn them. The concentration of glycerol in the body rises as the fat cells release more fatty acids.
The 'hypo-osmality study' bars show what happens in the bodies of the completely hydrated test subjects.
Below you can see the effect of an increased level of liquid on protein burning. Hypo = hydrated cells, hyper = dehydrated cells, iso = control group. The researchers measured the breakdown of protein via the oxidation of the amino acid leucine.
The conclusion: fat cells that are saturated with water release fats more easily; muscle cells that are full of water save proteins. Water is a perfect anabolic.
Eur J Clin Nutr. 2003 Dec;57 Suppl 2:S69-74.