Yes, the hosts poop.
Speaking to Entertainment Weekly, Westworld executive producer Lisa Joy said the following:
The hosts are basically organic. It's cheaper that way to print them out. They eat, they sleep, they have sex, they can poop. It's really like a human body with the one difference being where we have a brain, they have a CPU.
There's more to the quote but, let's focus on that one phrase. "They. Can. Poop."
If hosts are ingesting food or drink, yeah, it makes sense that it needs to be excreted. It can't just build up in the body forever. But, why do they have to poop? Isn't poop the waste after the body uses food for nutrition? If organic host bodies are using food for nutrition, can they get fat? This is kind of weird.
But, if we're being honest, I'll quote io9's Managing Editor, Jill Pantozzi:
I feel like there's only one reason they would actually poop and it's sex stuff.
Get ready for Westworld season three, where they will finally reveal the last unknown location - Scat World.
Season two debuts on HBO April 22. Check back here for, hopefully, poop-free Westworld coverage.