What is fasting in the Bible?

Understanding Matthew 6:16-18

Fasting is one of the most practiced yet least understood spiritual disciplines in Christianity. It appears throughout both testaments, from Moses on Mount Sinai (Exodus 34:28) to Jesus in the wilderness (Matthew 4:1-2) to the early church commissioning missionaries (Acts 13:2-3). Yet many modern Christians have never fasted or misunderstand its purpose.

What fasting IS:

At its simplest, fasting is voluntarily going without food for a set period of time for a spiritual purpose. It is not a hunger strike to pressure God, not a diet plan, and not a way to earn spiritual merit. It is an act of focused dependence — temporarily setting aside a legitimate physical need to focus entirely on God.

The Hebrew word for fasting (tsum) literally means 'to cover the mouth.' The Greek word (nesteuō) means 'not to eat.' Both are straightforward: fasting means not eating.

Biblical types of fasting:

1. Normal fast — Abstaining from food but drinking water. This is the most common biblical fast. Jesus fasted 40 days this way (Matthew 4:2 says He 'was hungry' but does not mention thirst).

2. Absolute fast — No food or water. Extremely rare and dangerous beyond 3 days. Esther called for this type: 'Do not eat or drink for three days, night or day' (Esther 4:16). Moses and Elijah both did supernatural 40-day absolute fasts (Exodus 34:28, 1 Kings 19:8) — these were miraculously sustained and should not be imitated.

3. Partial fast — Restricting certain foods. Daniel ate only vegetables and water for 21 days (Daniel 10:2-3). This is sometimes called a 'Daniel fast' in modern churches.

Why fast?

Scripture presents several purposes for fasting:

• Humbling yourself before God: 'I humbled myself with fasting' (Psalm 35:13). Fasting is a physical expression of spiritual dependence. Hunger reminds you that you are not self-sufficient.

• Seeking God's direction: The church at Antioch was 'worshiping the Lord and fasting' when the Holy Spirit spoke (Acts 13:2). Fasting clears mental and spiritual noise.

• Repentance: The people of Nineveh fasted in response to Jonah's warning (Jonah 3:5-9). Fasting accompanies genuine turning from sin.

• Intercession: Nehemiah fasted while praying for Jerusalem (Nehemiah 1:4). Esther fasted before approaching the king to save her people (Esther 4:16).

• Spiritual warfare: Jesus said some spiritual battles require 'prayer and fasting' (Mark 9:29 in some manuscripts). Fasting sharpens spiritual discernment.

Jesus' teaching on fasting (Matthew 6:16-18):

Jesus does not say 'if you fast' — He says 'when you fast,' assuming His followers will practice it. His concern is not whether to fast, but how. He warns against performative fasting — making yourself look miserable so others notice your piety. True fasting is between you and God. Wash your face. Go about your day. Let it be a secret between you and the Father.

The fast God chooses (Isaiah 58):

Isaiah 58 is the most important corrective passage on fasting. God rebukes Israel for fasting while simultaneously exploiting workers and fighting with each other. The fast God wants is not mere food abstinence — it is justice: 'Is not this the kind of fasting I have chosen: to loose the chains of injustice... to share your food with the hungry and to provide the poor wanderer with shelter?' (Isaiah 58:6-7). Fasting without justice is religious theater.

Practical wisdom:

• Start small: skip one meal and spend that time in prayer
• Stay hydrated during normal fasts
• Break your fast gently with light food
• Consult a doctor if you have medical conditions
• Fasting is not mandatory for salvation — it is a discipline for spiritual growth
• The goal is not suffering — it is focus