What does the Bible say about fasting?

Understanding Matthew 6:16-18, Isaiah 58:6-7, Joel 2:12, Acts 13:2-3

Fasting is one of the most ancient and universal spiritual practices in the Bible — yet it is also one of the most misunderstood. It appears in every major section of Scripture, practiced by patriarchs, prophets, kings, Jesus Himself, and the early church. Understanding what the Bible actually teaches about fasting requires separating the practice from both legalistic distortion and modern neglect.

What fasting is

Biblical fasting is the voluntary abstention from food (and sometimes drink) for a spiritual purpose. It is not a diet, a hunger strike, or a health regimen — though it may have physical effects. The biblical focus is always on the spiritual dimension: fasting is directed toward God, not toward the body.

The Bible describes several types of fasting:

Normal fast: Abstaining from food but not water, for a defined period. This is the most common form. Jesus fasted forty days in the wilderness and 'was hungry' (Matthew 4:2), suggesting He abstained from food but likely not water.

Absolute fast: No food or water. Esther called for this: 'Do not eat or drink for three days, night or day' (Esther 4:16). Paul neither ate nor drank for three days after his encounter with Christ (Acts 9:9). These are exceptional circumstances, not normal practice.

Partial fast: Restricting certain foods rather than all food. Daniel ate 'no choice food; no meat or wine touched my lips' (Daniel 10:3). This is sometimes called a 'Daniel fast.'

Old Testament fasting

Fasting pervades the Old Testament:

Moses fasted forty days and forty nights on Mount Sinai while receiving the law — 'he did not eat bread or drink water' (Exodus 34:28). This was a supernatural fast sustained by God's presence.

David fasted when his child was ill (2 Samuel 12:16), when his enemies were sick (Psalm 35:13), and as part of his regular devotional life (Psalm 109:24).

Elijah fasted forty days on the journey to Mount Horeb, sustained by angelic food (1 Kings 19:8).

Esther called a corporate fast before approaching the king to plead for her people's lives — a moment of national crisis requiring national spiritual preparation (Esther 4:16).

Daniel practiced regular fasting as part of his prayer life (Daniel 9:3, 10:3), and his fasts were associated with receiving profound prophetic revelations.

Ezra proclaimed a fast before the dangerous journey from Babylon to Jerusalem, seeking God's protection (Ezra 8:21-23).

Nehemiah fasted and prayed upon hearing of Jerusalem's ruins (Nehemiah 1:4).

Israel also had prescribed fasts. The Day of Atonement (Yom Kippur) was the only fast commanded in the Mosaic Law — described as a day to 'deny yourselves' (Leviticus 16:29). After the exile, four additional commemorative fasts were added (Zechariah 8:19).

The prophetic critique

The most important Old Testament passage on fasting may be Isaiah 58, where God rejects Israel's fasting because it had become empty ritual:

'Is not this the kind of fasting I have chosen: to loose the chains of injustice and untie the cords of the yoke, to set the oppressed free and break every yoke? Is it not to share your food with the hungry and to provide the poor wanderer with shelter?' (Isaiah 58:6-7).

God was not rejecting fasting itself but fasting divorced from justice, compassion, and genuine repentance. The same critique appears in Zechariah 7:5: 'When you fasted and mourned...was it really for me that you fasted?'

Jesus and fasting

Jesus both practiced and taught fasting:

His own fast: Before beginning His public ministry, Jesus fasted forty days in the wilderness and was tempted by Satan (Matthew 4:1-11). The fast prepared Him for the spiritual battle ahead.

His teaching: In the Sermon on the Mount, Jesus addressed fasting alongside prayer and giving — the three pillars of Jewish piety. He did not say 'if you fast' but 'when you fast' (Matthew 6:16), assuming His followers would fast. His concern was motive: 'Do not look somber as the hypocrites do, for they disfigure their faces to show others they are fasting' (6:16). True fasting is directed toward God, not toward an audience.

The bridegroom saying: When asked why His disciples did not fast (while John the Baptist's disciples did), Jesus answered: 'How can the guests of the bridegroom mourn while he is with them? The time will come when the bridegroom will be taken from them; then they will fast' (Matthew 9:15). This implies that fasting would resume after His ascension — as indeed it did.

Fasting and prayer: In some manuscripts, Jesus said certain demons could only be cast out 'by prayer and fasting' (Mark 9:29, KJV). While textual scholars debate whether 'and fasting' was original, the association between fasting and spiritual power runs throughout Scripture.

The early church

The book of Acts shows fasting as a normal practice in the early church:

The church at Antioch was 'worshiping the Lord and fasting' when the Holy Spirit said, 'Set apart for me Barnabas and Saul for the work to which I have called them.' They then 'fasted and prayed, placed their hands on them and sent them off' (Acts 13:2-3).

Paul and Barnabas appointed elders in each church 'with prayer and fasting' (Acts 14:23).

Paul himself mentions being 'in fastings often' (2 Corinthians 11:27, KJV).

Fasting was woven into the church's decision-making, commissioning, and spiritual discernment.

Purposes of biblical fasting

Repentance and humility: 'Even now, declares the LORD, return to me with all your heart, with fasting and weeping and mourning' (Joel 2:12). Fasting expresses the soul's seriousness about turning from sin.

Seeking God's guidance: The early church fasted before major decisions (Acts 13:2-3, 14:23). Fasting clears spiritual noise and sharpens discernment.

Intercession: Esther's fast was intercessory — pleading for her people's survival. Ezra fasted for safe travel. Daniel fasted while seeking understanding of prophecy.

Spiritual warfare: Jesus' wilderness fast preceded His direct confrontation with Satan. Fasting weakens the flesh's grip and strengthens spiritual resolve.

Mourning and grief: David fasted during his child's illness. The people of Jabesh Gilead fasted after Saul's death (1 Samuel 31:13).

Dependence on God: At its deepest level, fasting is a physical declaration that 'man shall not live on bread alone, but on every word that comes from the mouth of God' (Matthew 4:4). It is choosing God's sustenance over the body's demands.

Practical wisdom

The Bible does not prescribe a specific fasting schedule or method for Christians. It assumes fasting as a regular practice and focuses on the heart behind it. Key principles:

• Fast in secret, not for show (Matthew 6:16-18)
• Combine fasting with prayer — fasting without prayer is just going hungry
• Let fasting produce justice and compassion, not self-righteousness (Isaiah 58)
• Those with medical conditions should exercise wisdom — fasting is a spiritual discipline, not a mandate to harm the body
• Start small if fasting is new — missing one meal with intentional prayer is a legitimate beginning

Why fasting matters today

In a culture of constant consumption and instant gratification, fasting is countercultural in the deepest sense. It says: my appetites do not rule me. God's voice matters more than my stomach's voice. The discipline of saying no to the body's most basic demand — food — trains the soul to say no to every lesser temptation and yes to God's purposes. As Dallas Willard wrote, fasting 'reveals the things that control us.' What emerges when food is removed — irritability, anxiety, obsessive thoughts about eating — exposes what we normally medicate with consumption. Fasting strips away the padding and puts us face to face with our true spiritual condition — which is exactly where God can do His deepest work.