Of course, but metabolism also generates heat, and heat needs to be dealt with by evaporating water. Consider that the only human tissue that increases its meta

Of course, but metabolism also generates heat, and heat needs to be dealt with by evaporating water. Consider that the only human tissue that increases its metabolic rate just for the sake of it is brown adipose tissue[0], and its purpose is to generate body heat. On the other hand, compounds that can significantly increase base metabolism (and thus generate more water) such as 2,4-dinitrophenol[1] are dangerous because they can easily result in lethally high body temperature. That's why increasing metabolism with the sole purpose of generating water would be self-defeating. [0]: https://en.wikipedia.org/wiki/Brown_adipose_tissue https://en.wikipedia.org/wiki/Brown_adipose_tissue [1]: https://en.wikipedia.org/wiki/2,4-Dinitrophenol https://en.wikipedia.org/wiki/2,4-Dinitrophenol