Hunger Satisfied
Bottom line: When we fast for revival, our increased spiritual hunger is satisfied by God.
Prayer is the hand with which we reach out to God. Fasting is the hand with which we let go of the world.
There are at least four reasons why we should want to fast for revival: 1) fasting strengthens our prayers, 2) fasting expresses our repentance and desire to return to God, 3) fasting expresses our concern for God's work in us, among us, and through us to advance God's kingdom, and 4) fasting helps us to overcome temptation and sin in our lives.
The way Jesus spoke in the Mat. 6:16-18 implied that He expects us to fast, i.e. that we would and should fast. But we also have an expectation of God when we fast, i.e. that He will reward us. Isaiah chapter 58:11 gives us five rewards for fasting correctly: 1) God's guidance, 2) soul satisfaction, 3) inward strength, 4) outward fruit, and 5) hidden resources.