The SA 618 does not mention anything about a posek. My Rebbi the Matersdorfer Rav ztz’ would never rule against a religiuous observant doctor. I understand the gravity of eating of Yom Kippur but it is an issur gavre and not an issur cheftza. Therefore, the Torah put the responsibility to decide on the sick as specified in SA O’CH 618,1. If the sick says he must eat, hundred doctors will not trump his needs.
