What is waste product of muscle synthesis, creating unquenchable thirst?

Question

I know there's an assumption in the question but here's the situation. I'm on a lifting program I really enjoy, based on 3x/week compound barbell movements with progressive overload.

I know you have to eat, sleep and drink enough fluids to recover but it seems impossible to get all the water my muscles want. I always have to pee during the middle of the night. If I don't get enough water, after even a moderately intense workout which otherwise doesn't give me problems, I'm likely to get a migraine type headache onset in the morning lasting all day. I'm sure it's thirst related and my muscles are sucking up water, but when I pee, it is clear.

That is telling me it is not urea, correct? I also don't get intense thirst during or immediately after a workout. It is usually by the evening and especially night and morning so I assume it relates to muscle building (synthesis) and their need for it. Again it feels the muscles are sucking water from everywhere, but I feel it in my mouth, my throat and my head.

So my question is this. If the water I drink gets quickly eliminated, not kept, that makes me think it's being used for waste elimination ahead of local storage and if it's clear, then it's not urea, so I was wondering what waste product that would be associated with muscle synthesis or recovery? Then I can Google and learn more about it.

Or perhaps the water is just not getting into the muscles, being filtered first. If not, why not and what can I do?

Thank you!!

Answer 1

No, urea is not the cause of the yellow colour of urine. That's urobilin, which is an end product of the breakdown of red blood cells.

Urea is the body's means of disposing of metabolised amino acids, and so urea production (and need for disposal) will increase if you have a high protein diet. You'll need to urinate more to dispose of that, and drink more water to recover that lost in urine, but your urine will appear clear because urea is clear when dissolved in water, and the urobilin normally present in your urine is now diluted due to your increased urination frequency. (And while your body has extra proteins to dispose of, it still isn't cycling through red blood cells any faster than normal, so urobilin production hasn't increased.)