Anon needs a fucking doctor. I'm pretty sure after even like two weeks your colon becomes impacted so much as to not be able to naturally clear, much more and you start risking blockages so severe that they back up into the stomach and come out the other end, which is Super Super Bad.
I once went 4 days without shitting at first it was very much disturbing but after 2 days it was normal as hell in the end i had to force myself to shit as the temptation never came .
I’d imagine that on a liquid diet, depending on the ingredients, there’d be some amount of waste that’d get passed to the bowels. This is just conjecture on my part, though.
There's that old case of a fat dude who got fed intravenously by doctors and took vitamins and water for a whole year to lose weight. Iirc he only shit like twice. He said it took him a while to get over the feeling of being hungry.