Jabir (May Allah be pleased with him) reported: The Messenger of Allah (PBUH) said, "The inhabitants of Jannah will eat and drink therein, but they will not have to pass excrement, to blow their noses or to urinate. Their food will be digested producing belch which will give out a smell like that of musk. They will be inspired to declare the freedom of Allah from imperfection and proclaim His Greatness as easily as you breathe."[Muslim].
Belching the vapours of musk means that after meals one would not feel heaviness and acidity. On the other hand, the belch will give out scented air, and the food will be digested by it. There will be no excrement or urine there.
Secondly, recitation of Allah's Name will ever remain on their tongues without the least effort like the way we breathe, without any effort whatsoever. In other words the food in Jannah would be so light and fine that there would be no disagreeable urine excrement. On the other hand, there will only be fine smell like that of musk.