What makes fasting such a gift is its ability, with the help of the Holy Spirit, to focus our feelings and their expression toward God in prayer. Fasting walks arm in arm with prayer — as John Piper says, she is "the hungry handmaiden of prayer," who "both reveals and remedies."He concludes:
She reveals the measure of food's mastery over us — or television or computers or whatever we submit to again and again to conceal the weakness of our hunger for God. And she remedies by intensifying the earnestness of our prayer and saying with our whole body what prayer says with the heart: I long to be satisfied in God alone! (When I Don't Desire God, 171)That burn in your gut, that rolling fire in your belly, demanding that you feed it more food, signals game time for fasting as a means of grace. Only as we voluntarily embrace the pain of an empty stomach do we see how much we've allowed our belly to be our god (Philippians 3:19).
And in that gnawing ache of growing hunger is the engine of fasting, generating the reminder to bend our longings for food Godward and inspire intensified longings for Jesus. Fasting, says Piper, is the physical exclamation point at the end of the sentence, "This much, O God, I want you!" (Hunger for God, 25–26).
Fasting, like the gospel, isn't for the self-sufficient and those who feel they have it all together. It's for the poor in spirit. It's for those who mourn. For the meek. For those who hunger and thirst for righteousness. In other words, fasting is for Christians.I think a better question is "Why don't we fast?"
It is a desperate measure, for desperate times, among those who know themselves desperate for God.