What are some guidelines for fasting? How should I fast?

Isaiah 58:3-7“‘We have fasted before you!’ they say. ‘Why aren’t you impressed? We have been very hard on ourselves, and you don’t even notice it!’ I will tell you why!” I respond. “It’s because you are fasting to please yourselves. Even while you fast, you keep oppressing your workers. What good is fasting when you keep on fighting and quarreling? This kind of fasting will never get you anywhere with me. You humble yourselves by going through the motions of penance, bowing your heads like reeds bending in the wind. You dress in burlap and cover yourselves with ashes. Is this what you call fasting? Do you really think this will please the Lord? No, this is the kind of fasting I want: Free those who are wrongly imprisoned; lighten the burden of those who work for you. Let the oppressed go free, and remove the chains that bind people. Share your food with the hungry, and give shelter to the homeless. Give clothes to those who need them, and do not hide from relatives who need your help.”

The importance of fasting is not in the act or ritual but in our motives. It is not what you do but why you do it. We must truly want to hear from God and be prepared to act on what we hear. Our outward action of fasting needs to express the deepest desire of our hearts.

Matthew 6:16-18“And when you fast, don’t make it obvious, as the hypocrites do, for they try to look miserable and disheveled so people will admire them for their fasting. I tell you the truth, that is the only reward they will ever get. But when you fast, comb your hair and wash your face. Then no one will notice that you are fasting, except your Father, who knows what you do in private. And your Father, who sees everything, will reward you.”

Fasting, like prayer, should not be a public performance but part of our private relationship with God.

Daniel 9:3So I turned to the Lord God and pleaded with him in prayer and fasting. I also wore rough burlap and sprinkled myself with ashes.

Fasting and prayer often go together as two sides of a single coin. The purpose of fasting is to help us open our ears so we can hear from God.

Acts 13:2-3One day as these men were worshiping the Lord and fasting, the Holy Spirit said, “Appoint Barnabas and Saul for the special work to which I have called them.” So after more fasting and prayer, the men laid their hands on them and sent them on their way.

Fasting can also be used in corporate worship when a group of believers needs certain guidance from the Lord.