Should You Fast In This Heat?

When the temperature surpasses 90º, are you required to fast? For more people than you may realize, the answer is that not only are you are not required to fast, you really shouldn’t try to. You may even be breaking halakha if you do fast. First, some basic halakhic background. The Tisha B'av fast is not d’orita, it is not of biblical origin. Even though it is the most important of the non-biblical fasts, holding a position that is really quasi-biblical rather than fully rabbinic, threats to life and health push it off easier than they would on Yom Kippur.

Last year, I wrote a series of posts on the dangers of fasting in extreme heat – like New York City and much of the rest of the East Coast is expected to have today.

Here is the Tisha b'Av post from that series with some new material added at the end:

…[W]hen the temperature surpasses 90º, are you required to fast? For more people than you may realize, the answer is that not only are you are not required to fast, you really shouldn’t try to. You may even be breaking halakha if you do fast. First, some basic halakhic background. The Tisha B'av fast is not d’orita, it is not of biblical origin. Even though it is the most important of the non-biblical fasts, holding a position that is really quasi-biblical rather than fully rabbinic, threats to life and health push it off easier than they would on Yom Kippur.

An ill person generally eats and drinks on Yom Kippur. So do younger children. That’s because anyone to whom fasting presents a physical danger is prohibited from fasting (except in very narrow circumstances).

What danger could there possibly be from fasting in near-100º heat?

Let me list a few:

• Dehydration, which can easily take place even if the person is not active and remains indoors. Dehydration taxes the body in many different ways, including but not limited to cardiac function. Dehydration and resulting electrolyte imbalances can cause cardiac arrhythmias which themselves can cause heart attacks and sudden death. The young, the old, the healthy and the infirm all face this risk. Even seemingly robust 30-year-olds do.

• Not taking prescribed medicines – especially beta blockers and other cardiac-related medicines – risks cardiac malfunction. Those risks are magnified by the extreme heat.

• Bowel issues. People prone to bowel obstructions or impactions are at elevated risk during any fast (which is why many adults who have experienced one of these problems no longer fast – even short, winter fasts). That level of risk is dramatically elevated in extreme heat.

According to the Mayo Clinic, dehydration can cause:

• Swelling of the brain (cerebral edema). Sometimes, when you're getting fluids again after being dehydrated, the body tries to pull too much water back into your cells. This can cause some cells to swell and rupture. The consequences are especially grave when brain cells are affected.

• Seizures. Electrolytes — such as potassium and sodium — help carry electrical signals from cell to cell. If your electrolytes are out of balance, the normal electrical messages can become mixed up, which can lead to involuntary muscle contractions and sometimes to a loss of consciousness.

• Low blood volume shock (hypovolemic shock). This is one of the most serious, and sometimes life-threatening, complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body.

• Kidney failure. This potentially life-threatening problem occurs when your kidneys are no longer able to remove excess fluids and waste from your blood.

• Coma and death. When not treated promptly and appropriately, severe dehydration can be fatal.

Most people can handle an occasional sun-up to sundown fast if the weather isn’t exceedingly hot. Even so, some of them shouldn’t fast anyway, because a proper halakhic evaluation would forbid it.

In extreme heat – especially in consecutive days of extreme heat – the number of people who should not fast rises dramatically.

This is true even if yesterday was very hot but today is not, because it takes your body time to recover, and fasting impedes that recovery and exaggerates the damage done by the previous day's heat.

If there is any legitimate concern that fasting could sicken or injure you, do not fast.

The fast is not about testing your physical endurance, flirting with illness or worse. It is simply meant as a tool to focus your thoughts on repentance while it decreases your thoughts of worldly, physical things.

If you need to eat and drink this Tisha B'av to protect your health, do it.

You can demonstrate your understanding that this is a fast day by eating very plain food and by drinking water rather than soda, juice or coffee. (Although if you need to eat for health reasons, you can drink any of those without issue if you choose – except for grape juice and wine.)

It isn't the fast that is important – it is the teshuva, the repentance, that is.

For those of you are fasting, I hope your fast is an easy one.

And, as the saying goes, may we only know simhot.

On Hirhurm, Rabbi Asher Bush writes:

…Clearly, activities should be limited and staying in the Shul or home with air-conditioning is appropriate. However, if a person feels that they may faint due to the heat and merely going into a properly air-conditioned location does not help, they should drink. Particular caution should be paid by older individuals. At the same time, Rav Avigdor Nebenzhal (Yerushalayim B’Moadeha, Tshuva #14) points out that working is not a reason to permit eating, even if the work causes difficulty in fasting.…

Bush's entire post is based on how a person feels. If you feel that you are going to faint or if you now feel serious pain or distress, Rabbi Bush says, drink.

But that is wrong for several reasons, and it – again – points to the deficiencies of even well-meaning Orthodox and haredi rabbis.

Many people will not notice they are getting dangerously dehydrated until it is too late. They will suddenly feel weak, faint and experience cardiac palpitations.

While drinking at that point helps, it won't un-ring the bell and won't undo what has already begun going wrong in the body fast enough to save many people from being in real danger of becoming seriously ill – or dead.

Dehydration kills. Heat stroke kills. In extreme heat, no one should be fasting.

Unfortunately, rabbis almost universally lack the stones to be in this fight. The ones who really care will seek out and tell individual congregants privately that they should not fast, and some will issue statements (flawed as they will be) like Bush's, but they won't do what should be done and simply rule that no one should fast.

So lets be clear.

This fast is not from the Torah, you are not allowed to risk your life for it, and no non-Orthodox responsible physician will tell you that it is safe to fast in this heat.

Therefore, under halakha, you are really forbidden to fast.

Drink water. Keep yourself hydrated.

And fro God's sake – and for the sake of your health and the health of your families – don't listen to rabbis who know next to nothing about biology, medicine, science in general, or anything else not found in ancient texts that were, as we all know, often very wrong about their understanding of the human body and its health.

If you wouldn't send your 13-year-old child to your rabbi for a weekly bloodletting session, don't put that child's life – or your own – in that rabbi's hands.

Drink water, keep hydrated, repent and mourn what once was.