Endurance athletes of RoF

Do you find that a few days after a big event you have an absolute festival of pissing? 

If I put in a big effort on a Sunday I'll normally decant about 1.5kg on Wednesday morning.

Yes, I get both a piss spike and a massive hunger spike.  I'm doing an ironman on my birthday in a few weeks and fully intend to be pissing like a horse and gorging the next day.

I think the pissing thing is something about taking on lots of hydration (obvs) but then the body shutting down in trauma over the endurance stuff you're making it do.  I read somewhere this is why pro cyclists don't need to take a sh1t during a race.