Sometimes we fast to demonstrate our sincerity to God concerning something we truly desire. Ezra proclaimed a fast to ask God to protect His people as they journeyed to Jerusalem from exile. God responded by leading them safely to Jerusalem, delivering them from their enemies and ambushes along the way (Ezra 8:21 31).
Although fasting may show our sincerity, it does not guarantee we will receive what we desire. Maybe our request is not within God’s will, or we may be asking with the wrong motives. David fasted for seven days when God struck with illness the child Bathsheba conceived by David. David repented of his adultery with Bathsheba and the murder of her husband. He humbled himself, fasted and prayed, but the child still died (2 Samuel 12:15-18).
Through fasting, we can determine the sincerity and correctness of our requests.