Fasting in Judaism

First "Sin" or severing from God was about a dietary restriction, indicating how important what you put--or don't put--into your body is. Hence the following dietary restrictions.

But Judaism was never about ascetism. It was supposed to enjoy this world. Hence, no celibacy. Concurrently, it was also not to be indulged in. Hence, perhaps the restrictions, and the occasional fast days. The middle ground was always the way to go.

The Nazarite was punished for his full abstention. Also, there are ways to appreciate forbidden foods well via other foods. But that's the bare minimum. We should appreciate the moments when we are able to take a step back because of temporary abstention.

בראשית ב׳:ט״ז-י״ז

(טז) וַיְצַו֙ יְהֹוָ֣ה אֱלֹהִ֔ים עַל־הָֽאָדָ֖ם לֵאמֹ֑ר מִכֹּ֥ל עֵֽץ־הַגָּ֖ן אָכֹ֥ל תֹּאכֵֽל׃ (יז) וּמֵעֵ֗ץ הַדַּ֙עַת֙ ט֣וֹב וָרָ֔ע לֹ֥א תֹאכַ֖ל מִמֶּ֑נּוּ כִּ֗י בְּי֛וֹם אֲכׇלְךָ֥ מִמֶּ֖נּוּ מ֥וֹת תָּמֽוּת׃

Genesis 2:16-17

(16) And God יהוה commanded the Human, saying, “Of every tree of the garden you are free to eat; (17) but as for the tree of knowledge of good and bad, you must not eat of it; for as soon as you eat of it, you shall die.”

בראשית א׳

(ט) וַיֹּ֣אמֶר אֱלֹהִ֗ים יִקָּו֨וּ הַמַּ֜יִם מִתַּ֤חַת הַשָּׁמַ֙יִם֙ אֶל־מָק֣וֹם אֶחָ֔ד וְתֵרָאֶ֖ה הַיַּבָּשָׁ֑ה וַֽיְהִי־כֵֽן׃ (י) וַיִּקְרָ֨א אֱלֹהִ֤ים ׀ לַיַּבָּשָׁה֙ אֶ֔רֶץ וּלְמִקְוֵ֥ה הַמַּ֖יִם קָרָ֣א יַמִּ֑ים וַיַּ֥רְא אֱלֹהִ֖ים כִּי־טֽוֹב׃ ׃ (לא) וַיַּ֤רְא אֱלֹהִים֙ אֶת־כׇּל־אֲשֶׁ֣ר עָשָׂ֔ה וְהִנֵּה־ט֖וֹב מְאֹ֑ד וַֽיְהִי־עֶ֥רֶב וַֽיְהִי־בֹ֖קֶר י֥וֹם הַשִּׁשִּֽׁי׃ {פ}

Genesis 1

((9) God said, “Let the water below the sky be gathered into one area, that the dry land may appear.” And it was so. (10) God called the dry land Earth and called the gathering of waters Seas. And God saw that this was good. (31) And God saw all that had been made, and found it very good. And there was evening and there was morning, the sixth day.

God always refers to everything being good, but then...

בראשית ב׳:י״ח

(יח) וַיֹּ֙אמֶר֙ יְהֹוָ֣ה אֱלֹהִ֔ים לֹא־ט֛וֹב הֱי֥וֹת הָֽאָדָ֖ם לְבַדּ֑וֹ אֶֽעֱשֶׂה־לּ֥וֹ עֵ֖זֶר כְּנֶגְדּֽוֹ׃

Genesis 2:18

(18) God יהוה said, “It is not good for the Human to be alone; I will make a fitting counterpart for him.”

בראשית ג׳:א׳

(א) וְהַנָּחָשׁ֙ הָיָ֣ה עָר֔וּם מִכֹּל֙ חַיַּ֣ת הַשָּׂדֶ֔ה אֲשֶׁ֥ר עָשָׂ֖ה יְהֹוָ֣ה אֱלֹהִ֑ים וַיֹּ֙אמֶר֙ אֶל־הָ֣אִשָּׁ֔ה אַ֚ף כִּֽי־אָמַ֣ר אֱלֹהִ֔ים לֹ֣א תֹֽאכְל֔וּ מִכֹּ֖ל עֵ֥ץ הַגָּֽן׃

Genesis 3:1

(1) Now the serpent was the shrewdest of all the wild beasts that God יהוה had made. It said to the woman, “Did God really say: You shall not eat of any tree of the garden?”

Ther idea of abstainign from food was alwasy tied up with out connection to a God or a Higher Power, perhaps as a way of indicating that the world is not ourst o pluder and do as we please with.

שמות ל״ד:כ״ח

(כח) וַֽיְהִי־שָׁ֣ם עִם־יְהֹוָ֗ה אַרְבָּעִ֥ים יוֹם֙ וְאַרְבָּעִ֣ים לַ֔יְלָה לֶ֚חֶם לֹ֣א אָכַ֔ל וּמַ֖יִם לֹ֣א שָׁתָ֑ה וַיִּכְתֹּ֣ב עַל־הַלֻּחֹ֗ת אֵ֚ת דִּבְרֵ֣י הַבְּרִ֔ית עֲשֶׂ֖רֶת הַדְּבָרִֽים׃

Exodus 34:28

(28) And he was there with יהוה forty days and forty nights; he ate no bread and drank no water; and he wrote down on the tablets the terms of the covenant, the Ten Commandments.

There are indications that Moses fasted 3 times, for 40 days each.

In the words of Nahum Sarna: " In the presence of the ultimate Source of holiness and in communication with Him, Moses realizes a transformation of his self. He achieves a state that is beyond the ordinary range of human experience. In this extrasensuous world he transcends the constraints of time and is released from the demands of his physical being."

So fasting allows us to get to a place which is beyond us...

ויקרא ט״ז:כ״ט-ל׳

(כט) וְהָיְתָ֥ה לָכֶ֖ם לְחֻקַּ֣ת עוֹלָ֑ם בַּחֹ֣דֶשׁ הַ֠שְּׁבִיעִ֠י בֶּֽעָשׂ֨וֹר לַחֹ֜דֶשׁ תְּעַנּ֣וּ אֶת־נַפְשֹֽׁתֵיכֶ֗ם וְכׇל־מְלָאכָה֙ לֹ֣א תַעֲשׂ֔וּ הָֽאֶזְרָ֔ח וְהַגֵּ֖ר הַגָּ֥ר בְּתוֹכְכֶֽם׃ (ל) כִּֽי־בַיּ֥וֹם הַזֶּ֛ה יְכַפֵּ֥ר עֲלֵיכֶ֖ם לְטַהֵ֣ר אֶתְכֶ֑ם מִכֹּל֙ חַטֹּ֣אתֵיכֶ֔ם לִפְנֵ֥י יְהֹוָ֖ה תִּטְהָֽרוּ׃

Leviticus 16:29-30

(29) And this shall be to you a law for all time: In the seventh month, on the tenth day of the month, you shall practice self-denial; and you shall do no manner of work, neither the citizen nor the alien who resides among you. (30) For on this day atonement shall be made for you to purify you of all your sins; you shall be pure before יהוה.

ויקרא כ״ג:כ״ז-ל״ב

(כז) אַ֡ךְ בֶּעָשׂ֣וֹר לַחֹ֩דֶשׁ֩ הַשְּׁבִיעִ֨י הַזֶּ֜ה י֧וֹם הַכִּפֻּרִ֣ים ה֗וּא מִֽקְרָא־קֹ֙דֶשׁ֙ יִהְיֶ֣ה לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת־נַפְשֹׁתֵיכֶ֑ם וְהִקְרַבְתֶּ֥ם אִשֶּׁ֖ה לַיהֹוָֽה׃ (כח) וְכׇל־מְלָאכָה֙ לֹ֣א תַעֲשׂ֔וּ בְּעֶ֖צֶם הַיּ֣וֹם הַזֶּ֑ה כִּ֣י י֤וֹם כִּפֻּרִים֙ ה֔וּא לְכַפֵּ֣ר עֲלֵיכֶ֔ם לִפְנֵ֖י יְהֹוָ֥ה אֱלֹהֵיכֶֽם׃ (כט) כִּ֤י כׇל־הַנֶּ֙פֶשׁ֙ אֲשֶׁ֣ר לֹֽא־תְעֻנֶּ֔ה בְּעֶ֖צֶם הַיּ֣וֹם הַזֶּ֑ה וְנִכְרְתָ֖ה מֵֽעַמֶּֽיהָ׃ (ל) וְכׇל־הַנֶּ֗פֶשׁ אֲשֶׁ֤ר תַּעֲשֶׂה֙ כׇּל־מְלָאכָ֔ה בְּעֶ֖צֶם הַיּ֣וֹם הַזֶּ֑ה וְהַֽאֲבַדְתִּ֛י אֶת־הַנֶּ֥פֶשׁ הַהִ֖וא מִקֶּ֥רֶב עַמָּֽהּ׃ (לא) כׇּל־מְלָאכָ֖ה לֹ֣א תַעֲשׂ֑וּ חֻקַּ֤ת עוֹלָם֙ לְדֹרֹ֣תֵיכֶ֔ם בְּכֹ֖ל מֹשְׁבֹֽתֵיכֶֽם׃ (לב) שַׁבַּ֨ת שַׁבָּת֥וֹן הוּא֙ לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת־נַפְשֹׁתֵיכֶ֑ם בְּתִשְׁעָ֤ה לַחֹ֙דֶשׁ֙ בָּעֶ֔רֶב מֵעֶ֣רֶב עַד־עֶ֔רֶב תִּשְׁבְּת֖וּ שַׁבַּתְּכֶֽם׃ {פ}

Leviticus 23:27-32

(27) Mark, the tenth day of this seventh month is the Day of Atonement. It shall be a sacred occasion for you: you shall practice self-denial, and you shall bring an offering by fire to יהוה; (28) you shall do no work throughout that day. For it is a Day of Atonement, on which expiation is made on your behalf before your God יהוה. (29) Indeed, any person who does not practice self-denial throughout that day shall be cut off from kin; (30) and whoever does any work throughout that day, I will cause that person to perish from among the people. (31) Do no work whatever; it is a law for all time, throughout the ages in all your settlements. (32) It shall be a sabbath of complete rest for you, and you shall practice self-denial; on the ninth day of the month at evening, from evening to evening, you shall observe this your sabbath.

במדבר כ״ט:ז׳

(ז) וּבֶעָשׂוֹר֩ לַחֹ֨דֶשׁ הַשְּׁבִיעִ֜י הַזֶּ֗ה מִֽקְרָא־קֹ֙דֶשׁ֙ יִהְיֶ֣ה לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת־נַפְשֹׁתֵיכֶ֑ם כׇּל־מְלָאכָ֖ה לֹ֥א תַעֲשֽׂוּ׃

Numbers 29:7

(7) On the tenth day of the same seventh month you shall observe a sacred occasion when you shall practice self-denial. You shall do no work.

תהילים ל״ה:י״ג

(יג) וַאֲנִ֤י ׀ בַּחֲלוֹתָ֡ם לְב֬וּשִׁי שָׂ֗ק עִנֵּ֣יתִי בַצּ֣וֹם נַפְשִׁ֑י וּ֝תְפִלָּתִ֗י עַל־חֵיקִ֥י תָשֽׁוּב׃

Psalms 35:13

(13) Yet, when they were ill,
my dress was sackcloth,
I kept a fast—
may what I prayed for happen to me!^-b

ישעיהו נ״ח:ג׳

לָ֤מָּה צַּ֙מְנוּ֙ וְלֹ֣א רָאִ֔יתָ עִנִּ֥ינוּ נַפְשֵׁ֖נוּ וְלֹ֣א תֵדָ֑ע הֵ֣ן בְּי֤וֹם צֹֽמְכֶם֙ תִּמְצְאוּ־חֵ֔פֶץ וְכׇל־עַצְּבֵיכֶ֖ם תִּנְגֹּֽשׂוּ׃

Isaiah 58:3

“Why, when we fasted, did You not see?
When we starved our bodies, did You pay no heed?”
Because on your fast day
You see to your business
And oppress all your laborers!

The verb ENH means to humble yourself by not eating, realted to the hebrew workds Oni and Anav, Hence, fasting introduces humility in to our lives...

Yom Kippur is a catagory in and of itself. and then you have.....

זכריה ח׳:י״ט

(יט) כֹּֽה־אָמַ֞ר יְהֹוָ֣ה צְבָא֗וֹת צ֣וֹם הָרְבִיעִ֡י וְצ֣וֹם הַחֲמִישִׁי֩ וְצ֨וֹם הַשְּׁבִיעִ֜י וְצ֣וֹם הָעֲשִׂירִ֗י יִהְיֶ֤ה לְבֵית־יְהוּדָה֙ לְשָׂשׂ֣וֹן וּלְשִׂמְחָ֔ה וּֽלְמֹעֲדִ֖ים טוֹבִ֑ים וְהָאֱמֶ֥ת וְהַשָּׁל֖וֹם אֱהָֽבוּ׃ {פ}

Zechariah 8:19

(19) Thus said the LORD of Hosts: The fast of the fourth month, the fast of the fifth month, the fast of the seventh month, and the fast of the tenth month shall become occasions for joy and gladness, happy festivals for the House of Judah; but you must love honesty and integrity.

The four fasts that were decreed for the Temple..... and theren there's one more....

אסתר ד׳:י״ד-ט״ז

(יד) כִּ֣י אִם־הַחֲרֵ֣שׁ תַּחֲרִ֘ישִׁי֮ בָּעֵ֣ת הַזֹּאת֒ רֶ֣וַח וְהַצָּלָ֞ה יַעֲמ֤וֹד לַיְּהוּדִים֙ מִמָּק֣וֹם אַחֵ֔ר וְאַ֥תְּ וּבֵית־אָבִ֖יךְ תֹּאבֵ֑דוּ וּמִ֣י יוֹדֵ֔עַ אִם־לְעֵ֣ת כָּזֹ֔את הִגַּ֖עַתְּ לַמַּלְכֽוּת׃ (טו) וַתֹּ֥אמֶר אֶסְתֵּ֖ר לְהָשִׁ֥יב אֶֽל־מׇרְדֳּכָֽי׃ (טז) לֵךְ֩ כְּנ֨וֹס אֶת־כׇּל־הַיְּהוּדִ֜ים הַֽנִּמְצְאִ֣ים בְּשׁוּשָׁ֗ן וְצ֣וּמוּ עָ֠לַ֠י וְאַל־תֹּאכְל֨וּ וְאַל־תִּשְׁתּ֜וּ שְׁלֹ֤שֶׁת יָמִים֙ לַ֣יְלָה וָי֔וֹם גַּם־אֲנִ֥י וְנַעֲרֹתַ֖י אָצ֣וּם כֵּ֑ן וּבְכֵ֞ן אָב֤וֹא אֶל־הַמֶּ֙לֶךְ֙ אֲשֶׁ֣ר לֹֽא־כַדָּ֔ת וְכַאֲשֶׁ֥ר אָבַ֖דְתִּי אָבָֽדְתִּי׃

Esther 4:14-16

(14) On the contrary, if you keep silent in this crisis, relief and deliverance will come to the Jews from another quarter, while you and your father’s house will perish. And who knows, perhaps you have attained to royal position for just such a crisis.” (15) Then Esther sent back this answer to Mordecai: (16) “Go, assemble all the Jews who live in Shushan, and fast in my behalf; do not eat or drink for three days, night or day. I and my maidens will observe the same fast. Then I shall go to the king, though it is contrary to the law; and if I am to perish, I shall perish!”

Refered to as the Fast of Esther....

יואל ב׳:י״ב-י״ג

(יב) וְגַם־עַתָּה֙ נְאֻם־יְהֹוָ֔ה שֻׁ֥בוּ עָדַ֖י בְּכׇל־לְבַבְכֶ֑ם וּבְצ֥וֹם וּבִבְכִ֖י וּבְמִסְפֵּֽד׃ (יג) וְקִרְע֤וּ לְבַבְכֶם֙ וְאַל־בִּגְדֵיכֶ֔ם וְשׁ֖וּבוּ אֶל־יְהֹוָ֣ה אֱלֹהֵיכֶ֑ם כִּֽי־חַנּ֤וּן וְרַחוּם֙ ה֔וּא אֶ֤רֶךְ אַפַּ֙יִם֙ וְרַב־חֶ֔סֶד וְנִחָ֖ם עַל־הָרָעָֽה׃

Joel 2:12-13

(12) “Yet even now”—says the LORD—
“Turn back to Me with all your hearts,
And with fasting, weeping, and lamenting.” (13) Rend your hearts
Rather than your garments,
And turn back to the LORD your God.
For He is gracious and compassionate,
Slow to anger, abounding in kindness,
And renouncing punishment.

תענית ט״ו א:ה׳

הַזָּקֵן שֶׁבָּהֶן אוֹמֵר לִפְנֵיהֶן דִּבְרֵי כִבּוּשִׁין: אַחֵינוּ! לֹא נֶאֱמַר בְּאַנְשֵׁי נִינְוֵה ״וַיַּרְא אֱלֹהִים אֶת שַׂקָּם וְאֶת תַּעֲנִיתָם״, אֶלָּא: ״וַיַּרְא הָאֱלֹהִים אֶת מַעֲשֵׂיהֶם כִּי שָׁבוּ מִדַּרְכָּם הָרָעָה״, וּבַקַּבָּלָה הוּא אוֹמֵר: ״וְקִרְעוּ לְבַבְכֶם וְאַל בִּגְדֵיכֶם״.

Taanit 15a:5

The eldest member of the community says to the congregation statements of reproof, for example: Our brothers, it is not stated with regard to the people of Nineveh: And God saw their sackcloth and their fasting. Rather, the verse says: “And God saw their deeds, that they had turned from their evil way” (Jonah 3:10). And in the Prophets it says: “And rend your hearts and not your garments, and return to the Lord your God” (Joel 2:13). This teaches that prayer and fasting are insufficient, as one must also repent and amend his ways in practice.

משנה תענית ד׳:ו׳

חֲמִשָּׁה דְבָרִים אֵרְעוּ אֶת אֲבוֹתֵינוּ בְּשִׁבְעָה עָשָׂר בְּתַמּוּז וַחֲמִשָּׁה בְּתִשְׁעָה בְאָב. בְּשִׁבְעָה עָשָׂר בְּתַמּוּז נִשְׁתַּבְּרוּ הַלּוּחוֹת, וּבָטַל הַתָּמִיד, וְהֻבְקְעָה הָעִיר, וְשָׂרַף אַפּוֹסְטֹמוֹס אֶת הַתּוֹרָה, וְהֶעֱמִיד צֶלֶם בַּהֵיכָל. בְּתִשְׁעָה בְאָב נִגְזַר עַל אֲבוֹתֵינוּ שֶׁלֹּא יִכָּנְסוּ לָאָרֶץ, וְחָרַב הַבַּיִת בָּרִאשׁוֹנָה וּבַשְּׁנִיָּה, וְנִלְכְּדָה בֵיתָר, וְנֶחְרְשָׁה הָעִיר. מִשֶּׁנִּכְנַס אָב, מְמַעֲטִין בְּשִׂמְחָה:

Mishnah Ta'anit 4:6

The mishna discusses the five major communal fast days. Five calamitous matters occurred to our forefathers on the seventeenth of Tammuz, and five other disasters happened on the Ninth of Av. On the seventeenth of Tammuz the tablets were broken by Moses when he saw that the Jews had made the golden calf; the daily offering was nullified by the Roman authorities and was never sacrificed again; the city walls of Jerusalem were breached; the general Apostemos publicly burned a Torah scroll; and Manasseh placed an idol in the Sanctuary. On the Ninth of Av it was decreed upon our ancestors that they would all die in the wilderness and not enter Eretz Yisrael; and the Temple was destroyed the first time, in the days of Nebuchadnezzar, and the second time, by the Romans; and Beitar was captured; and the city of Jerusalem was plowed, as a sign that it would never be rebuilt. Not only does one fast on the Ninth of Av, but from when the month of Av begins, one decreases acts of rejoicing.

Fasting in Judaism is about abstention as well as clarity for reflection and connection (to both God and one's fellow man/woman. It's also about putting us in touch with our history. We asr fasting for things that happened thousands of years ago, but which we still celebrate....

By extension, there are also other benefits...

Fasting not in a religious or historical context

1. Promotes Blood Sugar Control by Reducing Insulin Resistance
Several studies have found that fasting may improve blood sugar control, which could be especially useful for those at risk of diabetes.

2. Promotes Better Health by Fighting Inflammation
While acute inflammation is a normal immune process used to help fight off infections, chronic inflammation can have serious consequences for your health.

3. May Enhance Heart Health by Improving Blood Pressure, Triglycerides and Cholesterol Levels

4. May Boost Brain Function and Prevent Neurodegenerative Disorders
Though research is mostly limited to animal research, several studies have found that fasting could have a powerful effect on brain health.

5. Aids Weight Loss by Limiting Calorie Intake and Boosting Metabolism

6. Increases Growth Hormone Secretion, Which Is Vital for Growth, Metabolism, Weight Loss and Muscle Strength

7. Could Delay Aging and Extend Longevity

8. May Aid in Cancer Prevention and Increase the Effectiveness of Chemotherapy