Waste is a normal part of processing food, not a byproduct of sin. Adam was created with intestines, no?Jesus ate food on several occasions after He was raised. Was it out of necessity? We aren't told that. But we are told that in heaven is the tree of life yielding fruit each month.
I would imagine that waste is a byproduct of sin, and that a person who is completely sinless person wouldn't have any waste. It's not something I dwell on because it's a matter of speculation if it's not addressed in scripture. I'd rather not lean in my own understanding