From my understanding, Roux-en-Y surgery involves the removal of the majority of the stomach, with only a roughly egg-sized pouch left. The purpose is to not only restrict the amount of food the new "stomach" can hold but also causes patients who undergo it to feel full when eating smaller portions. As far as I can tell, the nerves in the removed portion of the stomach are severed, and sensory signals are no longer received by the brain from it.
My question is: Since the patients can no longer feel the disconnected part of the stomach after a Roux-en-Y surgery, would they not continuously feel a hunger sensation due to the lack of stretch sensory signaling? Why are patients post-Roux-en-Y paradoxically feeling fuller faster rather than always hungry?
Of course, I must be missing something because otherwise this surgery would never be performed as much as it is.
Some follow-up questions:
What other pathways are involved in the feeling of fullness?
Does the remaining pouch even have stretch receptors? It is made of the top of the old stomach, so why would it logically need to feel stretch?