You should fast as long as God tells you to fast but use wisdom to not fast beyond your strength. Here are some options for different lengths of fasting.
One Meal Fast
Fasting for one meal is easy. Instead of eating at a regularly scheduled mealtime, use the time to pray and read your Bible. During a designated mealtime, sit down at your dining room table and open up your Bible rather than piling your plate with food.
Fasting for one meal is easy enough that even children can do it. Since kids have growing bodies, they should never go on an extended fast, but if they want to spend a special time with God, a one meal fast is a feasible option.
Some missions experts recommend setting aside one meal every week to pray for an unreached people group, or a particular country. One of my friends has committed to fasting every Monday during lunchtime in order to pray for the country of Afghanistan.
A twenty-four hour fast is the good length for your first experiment with fasting. If you have never fasted before, please do not stop eating for forty days for your first fast. It is best to start small and build up toward a longer fast.
My father used to fast from midnight to midnight, but he found himself staying up until after midnight in order to break the fast, so now he fasts from noon to noon. This is easier and perhaps a healthier way to fast.
Examples of one-day fasts in the Bible:
1. During the times of the Judges, the Israelites were fighting and they declared a one-day fast in order to seek God’s wisdom. “The Israelites, all the people, went up to Bethel, and there they sat weeping before the LORD. They fasted that day until evening and presented burnt offerings and fellowship offerings to the LORD” (Judges 20:26). Subsequently, God gave them complete victory.
2. The Israelites needed relief from the oppression of the Philistines so the prophet Samuel urged them to forsake their false gods and to dedicate their lives to the Lord. When they had all assembled together at Mizpah, Samuel began to intercede on their behalf. “On that day they fasted and there they confessed, "We have sinned against the LORD" (1 Samuel 7:6). When the Philistines attacked, God used thunder to vanquish Israel’s enemies. This victory was the beginning of a period of Israelite supremacy that lasted during the rest of Samuel’s life.
3. Saul commanded his soldiers not to eat one day while fighting the Philistines (1 Samuel 14:24).
4. David proclaimed a one day fast of mourning when Saul and Jonathan were killed in battle (2 Samuel 1:12).
5. Later David declared another fast when Abner was killed (2 Samuel 3:35).
The first three days of a fast are often the most difficult. A three-day fast is a real sacrifice that allows you to have time to develop a deeper relationship with God.
1. When the Jews were in danger of being exterminated by Haman’s evil decree, Queen Esther asked all her people to fast for three days. “Go, gather together all the Jews who are in Susa, and fast for me. Do not eat or drink for three days, night or day. I and my maids will fast as you do. When this is done, I will go to the king, even though it is against the law. And if I perish, I perish." (Esther 4:16). The purpose of this fast was to gain favor with the king in order to save the Jewish people.
2. Saul was on his way to Damascus to persecute Christians when a bright light from heaven blinded him. He fell to the ground and heard the voice of God. For three days after this encounter with the presence of God, Saul fasted (Acts 9:9, 17-19). The humbleness he demonstrated through his fasting was a key element in the restoration of his sight.
If you are seeking God’s will in a particular matter or if you want extra time to study God’s word intensely, this is the type of fast I recommend.
1. After King Saul was buried, his men declared a seven-day fast as they mourned for him (1 Samuel 31:13).
2. King David fasted for seven days when his child was sick (2 Samuel 12:16-23).
The men on the Apostle Paul’s boat fasted for fourteen days in the middle of a storm (Acts 27:33-34). Even though this fast was more because they were seasick then because they were spiritual, it is instructive to read about how Paul broke the fast. “He took some bread and gave thanks to God in front of them all. Then he broke it and began to eat” (Acts 27:35).
Twenty-one Day Fast
Daniel fasted in order to gain understanding and to humble himself. He wrote, “I, Daniel, mourned for three weeks. I ate no choice food; no meat or wine touched my lips; and I used no lotions at all until the three weeks were over” (Daniel 10:2-3). At the end of the twenty-one day period, an angel appeared to Daniel. The angel was sent from God at the beginning of Daniel’s fast but because of spiritual opposition, it took him three weeks to deliver God’s message.
This length of fast was observed by Moses twice (Exodus 24:18; 34:28; Deuteronomy 9:9, 18, 25-29; 10:10), Elijah (1 King 19:8), and Jesus (Matthew 4:2; Mark 1:13; Luke 4:2). I would not recommend this type of fast unless you are serious about seeking God’s face. Expect to be weak and tired after finishing. Because of spiritual pride or natural folly, some have made the mistake of trying to fast for longer than is physically wise. They have suffered health problems and in some cases have even died. It is best to begin by fasting for shorter amounts of time and work your way up to longer fasts.
This is an excerpt from Daniel's book: "The Power of Fasting." To order your copy, click HERE.