What Does the Bible Say About Fasting? (Simple A-Z Guide)

Larry Martinez

Fasting is mentioned in the Old and New Testaments, yet it is often misunderstood, particularly in its application under the New Covenant.

In this study, we will explore the biblical foundations of fasting, its expressions in both the Old and New Testaments, and how believers can approach fasting today.

What is Fasting?

In the Bible, fasting generally refers to abstaining from food and drink for a designated amount of time for a spiritual purpose.

It is not merely about refraining from certain foods or giving up a particular snack.

Sometimes, the term "fasting" is used explicitly, while other times, phrases like "afflict yourself" or "afflict your soul" are used.

Fasting in the Old Testament

The Command to Fast: The Day of Atonement

The only commanded fast in the Old Testament occurred on the Day of Atonement.

This was a sacred day of repentance and atonement for Israel's sins, involving fasting, sacrifices, and the symbolic sending of a scapegoat into the wilderness.

Leviticus 16:29–31 (ESV) — 29 “And it shall be a statute to you forever that in the seventh month, on the tenth day of the month, you shall afflict yourselves and shall do no work, either the native or the stranger who sojourns among you. 30 For on this day shall atonement be made for you to cleanse you. You shall be clean before the LORD from all your sins. 31 It is a Sabbath of solemn rest to you, and you shall afflict yourselves; it is a statute forever.

I want you to notice the phrase "afflict yourselves," which I stated refers to fasting.

Participation was mandatory on the Day of Atonement; failure to comply resulted in being cut off from the community. No work was permitted, emphasizing solemn reflection and repentance.

This is important to remember because many believe the Bible demands fasting for many reasons, but in the Old Covenant, this is the only one that was mandatory for all Israel.

Other Instances of Fasting

Fasting was practiced for various reasons. Let’s look at three main ones:

1. Mourning - After the deaths of Saul and his sons, the people fasted for seven days. (1 Samuel 31:13)

2. Penitence - The people of Nineveh fasted in response to Jonah’s warning, seeking God’s mercy. (Jonah 3:5–10)

3. Guidance in War - The Israelites fasted and sought God’s direction during a civil war against Benjamin. (Judges 20:26–28)

There are many other scriptures where men and women fasted, along with groups of people, but I believe they can be placed generally within these three categories I listed above.

So far, we see one mandatory command and three other types of fasts performed under the Old Covenant.

Now, let’s jump over to the New Testament and see what it says regarding fasting.

Fasting in the New Testament

Fasting remains present in the New Testament, but its purpose and understanding shift in light of the New Covenant.

Jesus Fasted

Matthew 4:1–2 (ESV) — 1 Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil. 2 And after fasting forty days and forty nights, he was hungry.

Jesus Himself fasted for 40 days in the wilderness.

John’s Disciples and the Pharisees

Matthew 9:14–15 (ESV) — 14 Then the disciples of John came to him, saying, “Why do we and the Pharisees fast, but your disciples do not fast?” 15 And Jesus said to them, “Can the wedding guests mourn as long as the bridegroom is with them? The days will come when the bridegroom is taken away from them, and then they will fast.

The disciples of John make it clear to Jesus that they fast, as do the Pharisees.

This would make it evident that the religious people of Jesus’s day spent time fasting, and further study will show that they did so often.

The Early Church

(See Acts 13:1-3; Acts 14:23)

We will look more into the early church and its way of fasting and purpose further into the lesson.

It’s essential to see the disciples apart from Jesus because they spent time fasting after his ascension to heaven.

There are fewer instances of fasting in the New Testament than in the Old Testament. I believe this is an important clue that can help clarify the difference.

How Many Days of Fasting?

The Bible provides details about the number of days various individuals fasted. Here’s a list, and I encourage you to look them up.

1 Day- 2 Samuel 1:12
3 Days- Esther 4:16
7 Days- 1 Samuel 31:13
10 Days- Daniel 1:11-14
21 Days- Daniel 10:1-13
40 Days- Matthew 4:1-2

As you can see from the examples above, people fasted for different lengths of time, which is a wonderful reminder as we approach fasting.

Remember, there’s no need to feel pressured to fast for as many days as someone else.

A New Covenant Perspective

Now that we have examined fasting in the Old and New Testaments, we must grasp the difference and how we should fast today.

Under the New Covenant, fasting is no longer a legal requirement for atonement because Jesus’ death on the cross has accomplished complete forgiveness and reconciliation.

It’s important to understand that we live on the other side of the cross, and because of the finished work, we must approach fasting with this in mind.

The finished work of Jesus changes our perspective and relationship to fasting. We live in a better and greater covenant and have a deeper relationship with God than those in the Old Covenant.

Only three texts list fasting after the cross. I want us to look at each text, pay attention to how and why they were fasting, and see if there is a difference between what they did and how the Old Testament saints did it.

Acts 14:23 (ESV) — And when they had appointed elders for them in every church, with prayer and fasting they committed them to the Lord in whom they had believed.

As the church grew, they fasted and prayed explicitly to appoint leaders. This highlights their commitment to seeking God’s guidance in making these critical decisions.

The second scripture is found in Acts 13. Again, the church fasts to ask God for direction and guidance as they appoint leaders.

1 Corinthians 7:5 (ESV) — Do not deprive one another, except perhaps by agreement for a limited time, that you may devote yourselves to prayer; but then come together again, so that Satan may not tempt you because of your lack of self-control.

In the context of marriage, Paul explains that couples may temporarily abstain from sexual relations to devote themselves to prayer.

Interestingly, some translations, such as the NKJV, KJV, and YLT, also include fasting in this context.

If fasting is included, it can be understood as a dedicated time of drawing closer to the Lord through devotion.

Under the New Covenant, fasting takes on this deeper purpose: Seeking direction from God and cultivating a closer relationship with Him.

God’s Concern with Our Attitude During Fasts

God cares not only about our fasting but also about our attitude and how we present ourselves during it.

Matthew 6:16–18

This passage emphasizes that fasting is a personal act between us and the Lord. We must avoid drawing attention to ourselves or announcing our fasting to everyone around us.

When you leave the house or go to work, don’t look so gloomy and appear to everyone as fasting.

As I stated, you don’t need to announce it to everyone (no Facebook posts saying you’re fasting).

Isaiah 58:3–9

This scripture emphasizes that fasting without a heart for justice and righteousness is meaningless.

True fasting involves humility, breaking oppression, and showing compassion to others.

God sees the act and motive, and remaining humble during this time is vital. This is not a time to boast and tell God how much you have fasted and expect Him to do.

For New Covenant believers, fasting should be:

Voluntary: No longer a command but a choice to seek God.

Purposeful: Focused on prayer, devotion, or seeking direction.

Private: Between the believer and God.

Conclusion

Fasting remains a powerful tool, not as a requirement for righteousness but as a means to deepen one’s relationship with God.

By understanding its biblical foundations and New Covenant context, believers can fast with greater clarity and purpose, honoring God in both heart and action.

How has fasting impacted your life in the past?

MATTHEW24

COURSE

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