Yosef Karo

“ Therefore, we feed them two or three medium-egg-worths and wait the time it takes to eat four egg-worths. Regarding drinking, we check with the sick person how much liquid when pushed to one side will look like a full mouth. ”

“ But if the doctor says they don't need and the sick person is unsure, we don't feed them.
סעיף ה
אם החולה אומר אינו צריך והרופא מסופק מאכילין אותו אבל אם הרופא אומר אינו צריך והחולה אומר איני יודע אין מאכילין אותו:
618:6 If the doctor says that they do not recognize the illness, he is treated like any other person and his words are not taken into consideration. Rem"a: That said, if [the sick person] greatly weakens to the point that most people think that they look like they are in danger if not fed, we feed them (Issur v'Heter ha'Aroch) . ”

“ If there is no kosher food nearby, we feed him forbidden food. If there are two types of forbidden food, one more forbidden than the other, we feed him the less forbidden one first. Rem"a: Regarding when they need meat and there is an animal that needs to be slaughtered or a carcass that died naturally that is ready, see 328:14. ”