Two-thirds to seventy percent of total body weight is water, with the majority of this water residing within the body's cells, including muscle tissue.

“two-thirds to seventy percent of our weight right I stood on the scale this morning like that number on the scale two-thirds to seventy percent of it is H2O yeah and then people say okay well wait how can that be because I get that my blood plasma is water that can't be where it all is no most of it is in the cells of our body and the muscle is of course no exception given that it's such a ubiquitous cell totally and in fact given that it occupies the vast majority mass in your body”