Fasting is not popular in a culture of instant self-gratification, when we are used to three daily meals plus snacks. The Bible however shows devout men and women did fast—which involves going without food and drink for a period of time. God even commands us to fast annually on the Day of Atonement.
Fasting is a very important, but often neglected, spiritual key and the Bible reveals God expects His followers to fast. When Jesus spoke about how to fast, He clearly expected His disciples would fast (Matthew 6:16-18). He did not say "if you fast" but "when you fast," emphasizing fasting as much as praying and doing good works.
Fasting is prominently mentioned in both the Old and New Testaments. Moses, David, Elijah, Ezra, Nehemiah, Esther, Daniel, Anna and Jesus Christ all fasted, and the apostle Paul engaged "in fasting often" (2 Corinthians 11:27).
Fasting is usually a time of deliberately choosing not to eat and drink. It can be for a whole day, part of a day or more than a day. A health fast is any temporary restricted diet that is supposed to have certain health benefits, but fasting for one's spiritual health, involves abstaining from food and drink while spending a lot of extra time in prayer, meditation and Bible study (Exodus 34:28; Ezra 10:6; Esther 4:16; Acts 9:9).
How long to safely fast depends on our individual health. If you are unsure about your health limitations we strongly advise you seek medical advice. Another option is a partial fast, such as mentioned in Daniel 10:3. A partial fast involves only taking as much food and/or water as necessary to be safe and spending extra time in prayer, Bible study and meditation. This can also be very profitable spiritually.
Godly fasting is poles apart from hunger strikes to gain political power or draw attention to a personal cause. It is an exercise in self-discipline, liberating us from slavery to our appetites while we focus on the true "Bread of Life," Jesus Christ (John 6:48-51, John 6:63).
A major purpose of fasting is to learn humility—to better understand how great God is and how weak, sinful and needy we are. King David tells us: "I humbled myself with fasting" (Psalms 35:13).
God delights in humble hearts, and Isaiah 66:2 we are told: "This is the one I esteem: he who is humble and contrite in spirit, and trembles at my word" (NIV). In Matthew 5:3 Jesus said, "Blessed are the poor in spirit [humble and dependent], for theirs is the kingdom of heaven."
The Bible has only one instruction regarding when to fast in Leviticus 23. We are commanded to fast on the Day of Atonement for 24 hours—from sundown to sundown (Leviticus 23:27-32). This fast day is listed among God's annual feast days. Besides the personal benefits of fasting, the Atonement fast has prophetic significance. To learn about the meaning of the Day of Atonement and its accompanying fasting, read the free Bible study aid God's Holy Day Plan: The Promise of Hope for All Mankind.
As well as the primary purpose of worshipping and drawing closer to God by fasting, it is also appropriate to beseech God to help with the serious needs for ourselves. When his country was being invaded, King Jehoshaphat "proclaimed a fast throughout all Judah" (2 Chronicles 20:1-3). At the preaching of Jonah, "the people of Nineveh believed God [and] proclaimed a fast" (Jonah 3:5). To beseech God for His protection, Ezra proclaimed a fast for all the exiles returning to Judah (Ezra 8:21-23). Esther requested that all the Jews in the Persian capital city fast so that they would be spared from genocide (Esther 4:16).
However, we must never view fasting as pressuring God to get what we want (Isaiah 58:3). Our attitudes should be like that of Jesus Christ when He prayed, "Not My will, but Yours, be done" (Luke 22:42). Isaiah 58:1-12 is a profound passage that contrasts right and wrong attitudes in fasting. It clearly shows fasting must not be a mere ritual.
Bible Study Guide - Tools For Spiritual Growth