Fasting is a discipline of abstaining from something good, like food, that helps us focus our lives and our satisfaction in Jesus. When talking about fasting, Jesus begins, “When you fast…” Notice that he doesn’t say, “If you fast…” (Matthew 6:16).
People who fasted in Scripture:
Moses (Deuteronomy 9:9,18) , Daniel (Daniel 9:3-5), David (2 Samuel, 12:16, Psalm 35:13), Jesus (Matthew 4:2), Paul (Acts 9:9, 13:1-4), and many others.
People fasted for different reasons: to mourn, to humble oneself before God, and to focus on praying to God for guidance or preparation.During Jesus’ fast, he quoted Deuteronomy and said, “It is written: ‘Man shall not live on bread alone, but on every word that comes from the mouth of God.’” (Matthew 4:4)
Fasting can help us understand this truth with new meaning. We can better understand that Jesus is the true Bread of Life, who sustains us and supplies our greatest needs (John 6:26-35). You will be physically reminded of your spiritual need. God will show you that He is what we are truly desperate for.
Hungering for God's Leading in Antioch
The situation is that Saul (Paul) and Barnabas and some of the other leaders in the church in Antioch were worshiping—ministering to the Lord—and fasting (v. 2). Judging by what happened we may assume, I think, that the burden that drove them to fast was this: "Where do we go from here as a church?" They were fasting to seek the leading of the Holy Spirit in the direction of their mission. They were hungry enough for God's leading that they wanted to say it with the hunger of their bodies and not just the hunger of their hearts. "We want your leading, O God! O Holy Spirit, what is your will for the mission of this church?"