I don’t believe you can figure out the water content of a living human. And if you can, I don’t want to know how.
You could just weigh a mummified body instead, figure out how much a living person of the same sex and height would weigh, and the difference would be water. (Not accounting for the internal organs that were removed during mummification).
People have said the fact is derived from experiment done on live human subjects by the WW2 Japanese torture unit, Unit 731.
I don’t believe you can figure out the water content of a living human. And if you can, I don’t want to know how.
You could just weigh a mummified body instead, figure out how much a living person of the same sex and height would weigh, and the difference would be water. (Not accounting for the internal organs that were removed during mummification).