Question:

Should Christians fast?

Answer:

"...[R]eligious oaths, vows, solemn fastings, and thanksgivings upon special occasions ... are in their several times and seasons, to be used in a holy and religious manner" (Westminster Confession of Faith, 21.5). Two Bible passages that support this summary statement of the Bible's teaching on fasting are the following:

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 friends of the bridegroom 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.

1 Corinthians 7:5. Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again, that Satan tempt you not for your incontinency.

The prophet Joel speaks more fully about the appropriateness of fasting, weeping, and mourning when there is repentance to be expressed to the Lord.

Joel 2:12-19. 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. Who knoweth if he will return and repent, and leave a blessing behind him; even a meat offering and a drink offering unto the LORD your God? Blow the trumpet in Zion, sanctify a fast, call a solemn assembly: gather the people, sanctify the congregation, assemble the elders, gather the children, and those that suck the breasts: let the bridegroom go forth of his chamber, and the bride out of her closet. Let the priests, the ministers of the LORD, weep between the porch and the altar, and let them say, Spare thy people, O LORD, and give not thine heritage to reproach, that the heathen should rule over them: wherefore should they say among the people, Where is their God? Then will the LORD be jealous for his land, and pity his people. Yea, the LORD will answer and say unto his people, Behold, I will send you corn, and wine, and oil, and ye shall be satisfied therewith: and I will no more make you a reproach among the heathen.

Our doctrinal standard, The Westminster Confession of Faith, chapter 21, section 5, when teaching about religious worship and the Sabbath day, teaches what the Bible says about fasting, as already noted. Here it is again, in the fuller context:

The reading of the Scriptures with godly fear, the sound preaching and conscionable hearing of the Word, in obedience unto God, with understanding, faith, and reverence, singing of psalms with grace in the heart; as also, the due administration and worthy receiving of the sacraments instituted by Christ, are all parts of the ordinary religious worship of God: beside religious oaths, vows, solemn fastings, and thanksgivings upon special occasions, which are, in their several times and seasons, to be used in an holy and religious manner.

May you use this answer to your question in a manner in keeping with the Scriptures and our historic standards unto the glory of God!