How do I know if I should fast on Yom Kippur? Rabbanit Debbie Zimmerman

The mishna in Yoma states:

“A pregnant woman who smells [food and feels compelled to eat it] is fed until she feels restored. A sick person is fed according to the word of experts. And if there are no experts there, they are fed according to their own word, until they say it is enough.”^[1]

The mishna cites two authorities who determine if a person needs to eat on Yom Kippur – an expert and the individual person. A halakhic expert is not involved in the decision.

The gemara clarifies and expands upon the mishna. It explains that this law is based on the maxim of “safek nefashot l’hakel,” (a somewhat literal translation is – “to be lenient when there’s risk of life”) if it’s suspected that observance of halakha may risk a life, we are lenient and permit that which is otherwise forbidden.^[2] This rule is born out of another rabbinic maxim – “there is nothing that stands before preserving life (pikuakh nefesh), except for avoda zara (pagan and foreign worship), gilui arayot (forbidden sexual relations), and spilling blood.”^[3]

The gemara also establishes that the individual is their own expert. Even if doctors do not think they need to eat, and even if there are 100 doctors who agree – if the individual says they need to eat on Yom Kippur, they are given food. The reasoning is “Lev yode’a marat nafsho” – “a heart knows its own bitterness/suffering.”^[4]

The gemara says the opposite is also true – if the doctor says the individual must eat and the individual believes this is unnecessary – we follow the doctor and feed the person on Yom Kippur. Furthermore, the gemara teaches that if expert opinion is divided, the individual eats on Yom Kippur.^[5] These determinations are based on the issue of “safek” – doubt. One must eat on Yom Kippur even if the danger is not clear, but rather doubtful.

Halakhic authorities agree and rule that if a person determines they need to eat on Yom Kippur, they are trusted and given food.^[6] If they are unsure or think they do not need to eat – one or more experts are consulted, and their opinion is followed.

Halakhic debate after the gemara centers around two main issues. The first is the trustworthiness of the expert/health professionals. Must they be God-fearing and/or Jewish? The second is the issue of shiurim, eating and drinking in limited measures. We will briefly address each issue from a practical standpoint.

The issue of the type and extent of risk and likelihood is also discussed in halakhic sources, but it grew in prominence in the last century, possibly due to a combination of factors such as changes in medical understanding, rabbinic leadership, and halakha observance. We will only briefly address this as cases of doubt should be decided on a case-by-case basis.

Must the doctor be Jewish/God-fearing? Who decides if it’s too risky?

In my humble opinion, this question is less relevant today, as I do not believe we should ask a doctor “should I fast on Yom Kippur?” Whether or not a doctor is Jewish or observant, they are generally not experts in halakha. Even if they are, you are not asking for their halakhic expertise. The doctor is there to advise you on the risks of fasting for twenty-five hours and how likely these risks are. Below I will add a list of suggested phrasing and questions to ask health professionals.

Additionally, “expert” is not limited to medical doctors, it can include a variety of health professionals and possibly others (such as a commanding officer in the army). Someone can be in generally good health or generally poor health, yet fasting may pose a short-term or long-term risk. Halakhic sources clearly view health as holistic – the mind and body, mental and physical, oneself and those that are dependent on them (such as a nursing baby). Again, these people do not decide the halakha – they tell you the possible risks of fasting.

The question of risk and likelihood is one of the more complicated ones. A risk of a slight headache is not an halakhically significant risk in and of itself. Risk of a migraine, fainting, or vomiting may be. Health professionals are rarely going to say something is 100% risk free. Aside from the liability issues, there are always slight chances and unknown factors.

Let’s take the everyday example of driving. People choose to take the risk daily, the risk being unlikely and the reasons for driving more compelling. Yet there are times people choose not to take the risk. It may be because of objectively dangerous road conditions, the driver’s capability or health, or the vehicle’s road-worthiness. The risks are combined and evaluated against the reason for driving. There is a tipping point when the risk is deemed too great to justify the action, but people will argue where that tipping point is. In the event of a storm a person may decide against driving to the movies, but that person will drive in more dangerous conditions to go to work, especially if they are an emergency worker.

Fasting is never risk-free;  little if anything in life is. But there are certain conditions that increase the risk – one’s mental and physical condition, and the circumstances surrounding them. A soldier or doctor on duty may be completely healthy yet be obligated to eat on Yom Kippur to avoid a risk to their life or that of another who depends on them.

At a certain point the combined factors may reach a tipping point that necessitates eating on Yom Kippur. When the individual or health professionals deem the risk is clear or likely, the halakha is also clear. When the risk is unclear or unlikely, one should consult with a halakhic expert.

There are times individuals are concerned or anxious about fasting even if health professionals do not believe they have a specific risk. This person may be advised to fast. This does not mean they should fast even if they believe it is risky, but it may mean they should begin the fast with the intent to fast as long as they feel safe.

As stated above, when experts and the individual determine there is no specific risk in fasting, or one is probably capable of safely fasting, there is always a possibility things will change. If at any point over Yom Kippur a person is concerned that continuing to fast (or eating/drinking in limited measures) is unsafe or will necessitate medical intervention – halakha says they should trust their judgment and eat/drink “until they say it is sufficient.” For example, someone should not get to the point where they are so dehydrated they need to seek urgent care to get intravenous liquids after the fast.

Shiurim – limited measures of food and drink

The second is the question of shiurim – eating and drinking in limited amounts. This is a complicated topic. It is clear that the mitzvah of preserving a life overrides the mitzvah to fast on Yom Kippur. Therefore, when fasting can lead to danger we are stringent to observe the mitzvah of preserving life and one’s mitzvah is to eat and/or drink on Yom Kippur. However, there are multiple aspects to the Yom Kippur fast. What happens if someone can safely observe some (but not all) of these aspects?

Halakhic consensus is that eating and drinking even minimal amounts is prohibited on Yom Kippur.  At the same time, halakha also dictates there is a certain minimum amount one must eat or drink to be liable for the consequences of eating or drinking on Yom Kippur.^[7] One is only liable if they do not eat more than a large date-sized portion or drink more than a cheek-full of liquid within the time it takes to eat half a loaf of bread (bikdei akhilat pras).^[8]

There are a few different ways to understand the distinction here. One possibility is based on the Torah’s description of Yom Kippur as a day of “inui” a day to impose another will over that of our bodies, to submit our bodies to God’s commands, Torah law, and our spiritual will.^[9] One aspect of inui is refraining from eating and drinking. The gemara explains that eating and drinking in measures smaller than those mentioned above does not satiate the body, and therefore does not violate the mitzvah of inui.^[10]

If it’s determined that a Jew needs to eat on Yom Kippur then eating and drinking is not prohibited for them and there is no liability. Halakhic authorities such as Rambam do not mention any limitations on such a person’s food intake. Others note that if it is safe for such a person to eat and/or drink in small amounts, that is what they should do. In this way they are able to observe both the mitzvah to preserve their life and more aspects of Yom Kippur.

“Give them less than a shiur and wait between one drink and another the time it takes to eat four egg-measures, or at least the time it takes to drink one revi’it. And if it’s estimated that these amounts are not sufficient for them or the sick person says this is the case or they are unsure in the matter – they are given everything they need to eat and drink.”

Rema adds one important word here “Immediately.”

Halakha is clear. We are stringent with health and preserving life.

Consulting an expert in halakha

The gemara does bring an example of consulting rabbis. A pregnant woman felt compelled to eat, and those around her asked the rabbi what to do. The rabbi answered that they should whisper to her that it is Yom Kippur. If this calms her, great; if not, give her food. Ultimately, the rabbi did not make the decision, that is left up to the woman (or her fetus, according to some explanations.)^[11] The rabbi gives over and applies the halakha.

Rabbis and halakhic responders have their own concerns. They may be concerned that people are looking for an “out” because they don’t want to fast on Yom Kippur or think that people and experts are overly anxious about minor or negligible risk. Conversely, they may be concerned people will put themselves at risk and fast when this is contrary to halakha. There is definitely concern that the halakha in this area is misunderstood.

Therefore, it is best to speak to a rabbi or halakhic responder who knows you personally and who you trust. You do not have to tell them your medical history or the reasons. You can either give them the bottom line or tell them the risks as you and your experts see them.

If a doctor determines safety and the halakha is clear, why consult with a rabbi or halakhic responder? In my humble opinion, there are at least four good reasons for this consultation:

1. After understanding one’s self-evaluation and that of one’s health professionals, a halakhic expert may be able to find ways the individual can safely observe aspects of Yom Kippur they did not know were possible. (For example there is halakhic reason to advise certain observances when it is deemed safe, such as drinking/eating in shiurim, fasting until morning, fasting until feeling unwell…)
2. A halakhic expert may be stricter about health risks than a doctor. For example, a doctor or individual may believe some risks are not sufficient to be considered “preserving life,” but the rabbi may disagree.
3. A Torah scholar can be especially helpful for someone who has trouble accepting the halakha that applies to them – whether it is to fast, eat/drink, or anything in between – the Torah scholar can help them understand why this is the halakha, the importance of observing it, and when the halakha changes. In addition to intellectual understanding, a Torah scholar may help the person find meaning in the way they can safely observe Yom Kippur.^[12]
4. As noted, there are gray areas where the likelihood of risk is unclear, and the halakha may be unclear. A halakhic responder may be able to help navigate these situations.

Rabbis, Torah scholars, halakhic responder – we are human. We may miss something or fail to listen or understand the situation. If an individual or their doctor feels this person’s determination is unsafe, there is no mitzvah to obey it. In this case, it is a good idea to consult with another Torah scholar (disclosing their conversation with the previous scholar). However, if this is not an option, one should remember that halakha trusts one’s own evaluation and that of medical experts.
Once again, no matter the halakhic decision, if circumstances on the fast change, one should eat or drink as necessary, and should only limit themselves to shiurim if it is safe.

Suggested questions and phrasing to ask oneself and health professionals:

1. What are the possible risks to my short- and long-term health if I were to refrain from eating and drinking for 25 hours? How likely are these risks?
2. If I need to eat/drink – is it safe for me to eat/drink in small amounts? To only drink? To only eat? To fast until morning? To fast until I start feeling unwell? What are the possible risks?
3. If I begin the fast or plan to eat/drink in limited amounts, what are signs I should look out for to switch plans?

Some health professionals, particularly those with experience with people who observe such fasts, may have a general answer they give everyone. This answer may be incongruent with halakha. For example, there’s significant debate around fasting for pregnant or breastfeeding women. Some health professionals and rabbis have a blanket answer. Be sure your answer is based on your own particular circumstances, and speak to those you consult with about the possibility of changing circumstances.