When Do Jews Fast?

In addition to Yom Kippur, there are many public and private fasts in Judaism.

Many people know that on Yom Kippur it is traditional for able-bodied adults to fast, consuming no food or beverages. But did you know that there are a lot of other Jewish fast days? Some are full-day fasts, and some are daylight only. Some are observed by the entire community, while others are specific to particular Jewish communities or individuals. 

There are many reasons Jews fast, including atonement, communal mourning, supplication or even to express gratitude. Jews don’t fast on Shabbat or joyous holidays, so as not to interfere with the celebration (except when Shabbat coincides with Yom Kippur). 

In ancient times, public and private fasts were common and practiced throughout the course of the year, often proclaimed with short notice. For that reason, there was a widely circulated calendar, called Megillat Ta’anit (Scroll of Fasts), that listed all the days on which it was not permitted to fast. There’s also evidence that some individuals made regular fasting their own private spiritual practice. For example, during the three years that the Second Temple was besieged by the Romans, Rabbi Tzadok fasted continually in an effort to save the city. The Shulchan Aruch discusses examples of people who fasted every day and became so accustomed to it they found it difficult to eat. These are extreme examples, but what’s clear is that Judaism has built the structure for an abundant cycle of both fasting and feasting.

Here are ten possible reasons Jews might be fasting:

1. It’s a major fast day

There are two major fast days on the Jewish calendar. The best known is Yom Kippur, the Day of Atonement. On that day Jews abstain from all food and drink, as well as wearing leather, bathing, intimacy and other luxuries so that they can focus on the sanctity of the day. Fasting on this day is for atonement.

The other major Jewish fast day is Tisha B’Av, which commemorates the destruction of both Temples in ancient times as well as other catastrophes that have befallen the Jewish people, from the Crusades to the Holocaust. This day, too, is marked by a full fast that extends from sundown to sundown; in this case it is a mourning ritual.

2. It’s a minor fast day

In addition to Yom Kippur and Tisha B’Av, there are four minor fast days on the Jewish calendar. These are observed only during daylight hours, which means they begin at sunrise and are completed at sundown the same day. Three of these fasts are connected to the destruction of the Temples: 

  1. Tzom Gedalia, observed on the 3rd of Tishrei (the day after Rosh Hashanah), this fast commemorates the murder of the Jewish governor of Judah, an act that was considered a tipping point leading to the destruction of the First Temple. 
  2. Asarah B’Tevet, the Tenth of Tevet, marks the beginning of Nebuchadnezzar’s siege of Jerusalem — also a precursor to the destruction of the First Temple. 
  3. Shiva Asar B’Tammuz, the 17th of Tammuz, commemorates the day on which the Romans breached the walls of the Second Temple. 

The fourth minor fast is Taanit Esther, the Fast of Esther. On the day before Purim, many Jews fast just as Esther fasted before she went to see King Ahasuerus and request that the decree of death against the Jews be lifted. (Note: If Purim falls on a Sunday, the fast is not held on Shabbat or even Erev Shabbat, but moved back to the Thursday before Purim.)

3. It’s their wedding day

There is a tradition of fasting on the day of one’s wedding from sunrise until the ceremony is complete, so that the couple eat for the first time that day when they are together in yichud (a brief period of seclusion after the marriage ceremony is complete). This is not a requirement (halakhah), but a custom (minhag), and it is more common in Ashkenazi communities than Sephardi communities.

There are several explanations for this practice. One is that the wedding day atones for the sins of the two partners and therefore it is, for them, like a personal Yom Kippur. Another is that the fast prevents the newlyweds — who may be tempted by all the booze at the pre-wedding banquets — from arriving at the huppah intoxicated. Marriage is a serious obligation and should be undertaken in a fully sober state.

4. It’s their conversion day

Converting to Judaism is often a lengthy and intense process that culminates with immersion in a mikveh (ritual bath). Some choose to fast on the day of their immersion until they emerge from the mikveh. 

In a rabbinic responsa, the 20th-century halakhic authority Rabbi Moshe Feinstein explained that a convert fasts on the day of immersion to atone for sins committed prior to conversion and compares the custom to a groom fasting on his wedding day.  

5. It’s Erev Passover

This fast applies specifically to firstborns (traditionally first sons) and commemorates the tenth plague on Egypt which took the lives of all firstborn Egyptians, while firstborn Israelites whose homes were marked with lamb’s blood were spared. This fast is observed from sunrise on the 14th of Nisan until the Passover seder that evening.

6. It’s Sigd

Sigd is an Ethiopian Jewish holiday observed 50 days after Yom Kippur on the 29th of Heshvan. Traditionally, Sigd is marked by fasting from sunrise until mid-afternoon. 

According to Beta Israel tradition, the individual’s sins are forgiven by God on Yom Kippur, while communal introspection and repentance occurs during the 50 days following Yom Kippur. Sigd is believed to be the day that God would forgive all communal sins, as well as the date on which God first revealed himself to Moses. 

Most of the Ethiopian Jewish community is concentrated in Israel, where a national Sigd celebration is held in Jerusalem annually. 

7. It’s an emergency

An entire tractate of the Talmud, Ta’anit, explores the rules around fasting in response to a communal emergency such as a drought, plague or a marauding army. Sometimes, these fasts are observed only by certain leaders in the community, and sometimes by all adults. Usually they are daylight fasts held on Monday and Thursday and can last just a few days or go on for weeks, depending on the emergency. Fasting in the face of disaster is less common in modern times, but some Jews in Israel did declare a fast in response to the coronavirus pandemic in 2020.

8. It’s “Little” Yom Kippur

The custom of fasting on the day before each Rosh Chodesh (first of the Hebrew month) seems to have originated with the kabbalists of Safed. It was never a fast observed by the entire community, but the reserve of particularly pious members. Dubbed Yom Kippur Katan, or “Little Yom Kippur,” as the name implies this is a day of fasting for atonement, allowing the participant to enter the new month with a clean slate. The inspiration for Yom Kippur Katan comes from the biblical prescription to bring a sin offering on the first of every month (Numbers 28:15).

Yom Kippur Katan is not observed for four months of the year. The days before Rosh Chodesh Tishrei and Rosh Chodesh Heshvan are not considered Yom Kippur Katan because of their proximity to Rosh Hashanah and Yom Kippur. The days before Rosh Chodesh Tevet and Rosh Chodesh Nisan are also not fast days because the first falls during Hanukkah and the second is similarly part of the Passover season. If the last day of a month falls on a Shabbat, Yom Kippur Katan is moved back to Thursday.

9. They had a bad dream

Jewish tradition takes dreams seriously. Joseph’s dreams came true, after all, as did the dreams he interpreted for the pharaoh and his servants. And in the Talmud, Rav Hisda teaches: “A dream not interpreted is like a letter unread.” (Berakhot 55a) So a bad dream is not just unpleasant; it can be a dangerous omen. To reverse possible future misfortune that one learns of in a dream, there is a tradition of fasting the day after one has had such a dream to affect atonement. In fact, according to the Shulchan Aruch, one may fast on the day following a bad dream even if that happens to be Shabbat — a day fasting is normally prohibited. But if you do, then you should also fast the next day as well (Sunday) to atone for fasting on Shabbat! (Shulchan Aruch, Orach Chayim, 288:4)

10. Someone dropped a Torah scroll

There is a common belief that Jews who witness a Torah scroll being dropped must fast for 40 days (daylight only). The sources for this practice are murky, but some contemporary congregations have responded to a dropped Torah in this way.

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