Sitting next to my father, the rabbi, on the synagogue dais on Yom Kippur morning, I wondered how long I could last before breaking my fast. The lunch bag my mother gave me seemed to call out to me from the rabbi’s office where I had left it. By 10 a.m. I could stand it no longer. It was already three hours after my breakfast time. I felt the envious eyes of some worshippers follow me as I crept away toward the office. Years later I would come home from shul to visit my father, now ailing in bed on Yom Kippur. I would comfort him as he begrudgingly followed doctor’s orders, eating just one small morsel of bread at a time, waiting ten minutes before eating another. And I would tell him what he told me years back: “It’s OK, it’s a mitzvah for you to eat.”
Regarding Yom Kippur the Torah states “ta’anu et nafshoteichem” – you shall afflict your souls. According to the interpretation of the Talmud, the words mean that on Yom Kippur one may not eat, drink, bathe one’s body, wear leather shoes or engage in marital relations. The punishment for disregarding the prohibition against eating or drinking on Yom Kippur is karet, premature death at the hand of God. Disregarding the other prohibitions mentioned above is not punishable by karet but is nevertheless prohibited.
Two conditions must exist, however, for the punishment of karet to apply to eating and drinking on Yom Kippur. First, one must have eaten an amount of food equivalent to kotevet hagasah (the size of a large date) or imbibed an amount of liquid equal to melo lugma (a cheek full of fluid) – between 32-40 grams. Second, these quantities must have been consumed within a period of time equivalent to kedei achilat peras, the time it takes a person to eat half a loaf of bread. According to most opinions, this is equivalent to between 8 and 10 minutes. In the case of Yom Kippur, the Torah uses the term inui, affliction, and according to the Talmud a person begins to feel the first signs of relief from hunger or thirst only after eating or drinking the above quantities. These quantities differ from the olive (or revi’it) size (equivalent to the volume of 1.25 eggs) that applies to non-kosher food or drink or to chametz on Pesach.
A sick person who is told by a doctor (or feels on his own) that refraining from eating and drinking on Yom Kippur will or may aggravate the sickness to the point of danger, is required by halacha to eat and drink on Yom Kippur. The halacha sees no merit in jeopardizing one’s health in order to fast on Yom Kippur. Quite to the contrary, the halacha roundly condemns such irresponsible behavior. “There is nothing virtuous about a sick person endangering himself by fasting on Yom Kippur. The Torah will hold such a person responsible for the harm he causes himself,” warns the Ramban. The rule of thumb here is to follow the doctor’s instructions. In this case, the doctor is the rabbi.
If the doctor or the patient is uncertain as to the effects of fasting on the health of the patient, one may take the following course of action. Preferably before Yom Kippur, (but this may also be done on Yom Kippur if one forgot) one should measure out quantities of food each equal to the volume of a large date. This can best be done by inserting the food into a measuring cup up to the 30-gram line. The patient should eat this quantity of food on Yom Kippur and then wait about ten minutes before eating the next portion in the same quantity and so on.