Fasting is when we deny ourselves of something in order to go deeper in our spiritual life and glorify God. It is a way of demonstrating that we are serious with our relationship with God and our dissatisfaction with sin. The Holy Spirit reveals our true spiritual condition which results in brokenness and our desire to repent and live a transformed life.
And as a widow till she was eighty-four, she did not depart from the temple,
worshipping with prayer and fasting.
Why do we fast? We fast because we need to confirm what we hunger and thirst for like the Psalmist in Psalm 42:2 and be truly devoted to prayer. We also take our eyes away from the things of the world and focus completely on God. It is a biblical way of humbling ourselves in the sight of God.
What do we fast from? Fasting is abstinence not only from food but from any legitimate thing for spiritual purpose. We can fast from watching television, computer, social media and so on. Even married couples were advised by St Paul to abstain from sexual intimacy for a limited time so that they can devote themselves to prayer (1 Corinthians 7:5).
The Prophet Isaiah encourages us in the book of Isaiah 58 to engage in true fasting which should be a lifestyle. It involves being humble, loosening the chains of injustice, freeing the oppressed, feeding the hungry and care for the needy.