Melissa-
You do realize that nutrients are absorbed in the ileum whether you have a colon or not, right? What difference does not having a colon make? Your transit time of food through the ileum is what counts, and it is only marginally less with a J pouch than with a colon. Your colon functions to absorb water and break down the waste. Without the colon, the transit time through the ileum is only shortened to the extent of the shortening of the ileum for the J Pouch. And to the extent that motility is increased after surgery, for which a category of drugs called anti spasmodics exists to neutralize any excessive motility.
Given the only marginal diminution in transit time through the ileum, nutrient absorption should be the same.
The reason you see the kale crapped out whole is that the colon had bacteria that would have broken it down into crap. Since the colon is gone it doesn’t get broken down into crap but instead what comes out is the “stewed” kale, see the soup analogy of my prior post. The fact that it looks like a veggie rather than shit doesn’t change the fact that it passed through your ileum where nutrients were absorbed.