Am I supposed to fast? Yes, Jesus taught us to fast and receive the Father’s rewards.
Matthew 6:16-18 Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward. But thou, when thou fastest, anoint thine head, and wash thy face; That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly. Matthew 9:14-15 Then came to him the disciples of John, saying, Why do we and the Pharisees fast oft, but thy disciples fast not? And Jesus said unto them, Can the children of the bridechamber mourn, as long as the bridegroom is with them? but the days will come, when the bridegroom shall be taken from them, and then shall they fast.
What is fasting for? To humble ourselves, seek guidance, and allow our born again spirit to rule.
Ezra 8:21 Then I proclaimed a fast there, at the river of Ahava, that we might afflict (humble) ourselves before our God, to seek of him a right way for us, and for our little ones, and for all our substance. Daniel 9:3 And I set my face unto the Lord God, to seek by prayer and supplications, with fasting, and sackcloth, and ashes: Galatians 5:17 For the flesh (nature of mankind) lusteth against the Spirit (nature of Christ), and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.
What does fasting accomplish?
Victory in your life. Isaiah 58:6 Is not this the fast that I have chosen? to loose the bands of wickedness, to undo the heavy burdens, and to let the oppressed go free, and that ye break every yoke?
Victory for others. Mark 9:26-29 And the spirit cried, and rent him sore, and came out of him: and he was as one dead; insomuch that many said, He is dead. But Jesus took him by the hand, and lifted him up; and he arose. And when he was come into the house, his disciples asked him privately, Why could not we cast him out? And he said unto them, This kind can come forth by nothing, but by prayer and fasting.
Victory in the church. 2 Chronicles 20:3, 15, 17, 22 And Jehoshaphat feared, and set himself to seek the LORD, and proclaimed a fast throughout all Judah. … And he said, Hearken ye, all Judah, and ye inhabitants of Jerusalem, and thou king Jehoshaphat, Thus saith the LORD unto you, Be not afraid nor dismayed by reason of this great multitude; for the battle is not yours, but God’s. … Ye shall not need to fight in this battle: set yourselves, stand ye still, and see the salvation of the LORD with you, O Judah and Jerusalem: fear not, nor be dismayed; to morrow go out against them: for the LORD will be with you. … And when they began to sing and to praise, the LORD set ambushments against the children of Ammon, Moab, and mount Seir, which were come against Judah; and they were smitten. Judges 20:26-28 Then all the children of Israel, and all the people, went up, and came unto the house of God, and wept, and sat there before the LORD, and fasted that day until even, and offered burnt offerings and peace offerings before the LORD. And the children of Israel enquired of the LORD, (for the ark of the covenant of God was there in those days, And Phinehas, the son of Eleazar, the son of Aaron, stood before it in those days,) saying, Shall I yet again go out to battle against the children of Benjamin my brother, or shall I cease? And the LORD said, Go up; for to morrow I will deliver them into thine hand.
True repentance. Jonah 3:5 So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them. 1 Samuel 7:6 And they gathered together to Mizpeh, and drew water, and poured it out before the LORD, and fasted on that day, and said there, We have sinned against the LORD. And Samuel judged the children of Israel in Mizpeh.
Personal healing. Isaiah 58:8 Then shall thy light break forth as the morning, and thine health shall spring forth speedily: and thy righteousness shall go before thee; the glory of the LORD shall be thy rereward.
Quick answers to prayers. Isaiah 58:9 Then shalt thou call, and the LORD shall answer; thou shalt cry, and he shall say, Here I am. If thou take away from the midst of thee the yoke, the putting forth of the finger, and speaking vanity;
Anointed ministry. Isaiah 58:10-12 And if thou draw out thy soul to the hungry, and satisfy the afflicted soul; then shall thy light rise in obscurity, and thy darkness be as the noonday: And the LORD shall guide thee continually, and satisfy thy soul in drought, and make fat thy bones: and thou shalt be like a watered garden, and like a spring of water, whose waters fail not. And they that shall be of thee shall build the old waste places: thou shalt raise up the foundations of many generations; and thou shalt be called, The repairer of the breach, The restorer of paths to dwell in. Acts 13:2 As they ministered to the Lord, and fasted, the Holy Ghost said, Separate me Barnabas and Saul for the work whereunto I have called them. Acts 14:23 And when they had ordained them elders in every church, and had prayed with fasting, they commended them to the Lord, on whom they believed.
To hasten the coming of the Lord. Joel 1:14-15 Sanctify ye a fast, call a solemn assembly, gather the elders and all the inhabitants of the land into the house of the LORD your God, and cry unto the LORD, Alas for the day! for the day of the LORD is at hand, and as a destruction from the Almighty shall it come. Joel 2:12-13 Therefore also now, saith the LORD, turn ye even to me with all your heart, and with fasting, and with weeping, and with mourning: And rend your heart, and not your garments, and turn unto the LORD your God: for he is gracious and merciful, slow to anger, and of great kindness, and repenteth him of the evil.
See also; Four reasons to fast