Isaiah 58:6

(Rather) is this not the fast which I choose, to undo the bonds of wickedness, to tear to pieces the ropes of the yoke, to let the oppressed go free and break apart every (enslaving) yoke?

Fasting before God helps to remove the bondage of sin. We are no longer slaves to that sin when we turn our flesh over to God to be redeemed and deny ourselves a short time of food. God wants His people to be free from any hindrances so that we can fulfill our call here on earth. Fasting helps cut through those barriers.