Saw a video a while ago where an astronaut talks about the hassle of doing your business in space. Apparently you have to be really aware of your bowels because gravity isn't pulling on the waste and you don't get that feeling of "it's time to go" as strongly.

More generally, just knowing what I know about how the body works. Digestion is just a bunch of muscly tube shoving nutrients around. It's not as gravity dependent as you'd think. Might make your guts feel funky but doesn't affect a whole lot.