How-to-fast
Short answer: In Matthew 6:16-18 Jesus assumes his disciples will fast and tells them not to look miserable so people notice. Wash your face, go about your day, and fast before your Father who sees in secret. Practically, start with one meal or one day, drink water, keep it between you and God, and pair it with prayer rather than treating it as a hunger contest. Fasting is never a technique that manipulates God. It is a voluntary setting aside of food for a season to seek him. Scripture ties fasting to repentance, to urgent prayer, to listening for direction, and to works of mercy. Done for an audience, it earns only that audience. Done in secret, it is seen by the Father.
Jesus says when you fast, not if
Most teaching about fasting drifts toward the question of whether a Christian has to do it. Jesus settles that differently. In Matthew 6:16 he says, "Moreover when you fast, don't be like the hypocrites, with sad faces." He makes the same assumption elsewhere in the Sermon on the Mount: when you give, when you pray, when you fast. The command is not, you must fast. The assumption is that his disciples will fast, and the command is about how.
Notice what Jesus does not do. He does not prescribe a schedule, a duration, or a type of fast. He does not say how many meals or which foods. He does not rank fasting above prayer or giving. The whole paragraph sits inside a larger section about religious practice done for the Father rather than for people. Fasting is one of the three practices he names, alongside almsgiving and prayer.
That silence matters for anyone trying to build a rule book. Scripture gives examples of one-day fasts, of a fast lasting many days, of fasting from food and drink, and of corporate fasts called by leaders. It never gives a universal minimum. So the honest answer to how to fast begins with freedom: you choose the form, and you answer to God for the motive.
The one thing that ruins a fast
Jesus names the failure mode plainly. The hypocrites disfigure their faces so that they may be seen by men to be fasting. His verdict is that they have received their reward. The fast accomplished exactly what it was aimed at: human notice. Nothing was left over for God to reward.
The remedy he gives is almost comically practical. Anoint your head and wash your face, so that you are not seen by men to be fasting, but by your Father who is in secret. In other words, do the normal grooming. Don't announce it. Don't sigh loudly at lunch, don't post about it, don't mention it in conversation. Let your face look like any other day.
This is a heart issue clothed as a grooming instruction. The question is not whether anyone will ever find out. It is whom you are performing for. If the fast exists to be noticed, it is theater. If it exists because you are seeking God, the secrecy is not concealment from him but honesty before him. Your Father sees what is secret, and he rewards.
What fasting is actually for
The Bible's examples cluster around a few purposes, and none of them is earning favor. Joel 2:12-13 reads, "Yet even now," says Yahweh, "turn to me with all your heart, and with fasting, and with weeping, and with mourning." Fasting appears there as the bodily language of repentance, an outward expression of inward turning. It is not a penalty paid to God; it is a person casting themselves on his mercy
Isaiah 58 adds a second purpose. Israel complains that they fasted and God did not notice. God's answer is that their fast coexisted with oppressing workers and quarreling. The fast he wants looses the bonds of wickedness, shares bread with the hungry, and shelters the poor. Fasting and mercy belong together. A hungry stomach plus an unchanged life is not the fast God chose.
A third purpose appears in Acts 13:2-3. As the church at Antioch served the Lord and fasted, the Holy Spirit spoke and set apart Barnabas and Saul. Fasting here accompanies worship and listening, a way of clearing space to hear direction. And 1 Corinthians 7:5 treats it as a marital season, by consent, for prayer, not by one spouse depriving the other.
Starting small: a first fast that is actually doable
The most common reason people never fast is that they aim too high. They plan a week, fail on day two, and conclude they are not the fasting type. Scripture does not require heroics. Start with one meal. Skip lunch, spend that time praying, and eat dinner normally. Do that once a week for a month and see how it goes.
A one-day fast from food is the ordinary starting point, and it is what most examples in Scripture look like. Drink water. If you have never fasted, jumping to multiple days is unwise. If you have medical conditions, are pregnant, have a history of disordered eating, or take medication with food, do not fast from food without medical counsel. The principle is voluntary, not compulsory.
Some people fast from something other than food because of health limits: media, sweets, a habitual pleasure, sleep. This is a real discipline and can be offered to God, but it is worth being honest that it is not quite what the biblical examples describe. Food is the ordinary fast. Where health prevents that, a modified fast is a reasonable accommodation, not a lesser spirituality.
What to do with the hunger
Hunger is the point, but not because hunger is virtuous. Hunger is a signal, and fasting works by turning that signal into prayer. When you notice you are hungry, pray. That reflex is the discipline. Otherwise the day fills with irritability and you have simply skipped lunch.
Plan the time you would have spent eating. Use the meal break for Scripture, for intercession, for repentance, for a walk and prayer. Jesus was led by the Spirit into the wilderness, and Matthew 4:1-2 tells us he fasted there and was tempted. Fasting does not exempt you from temptation; sometimes it exposes you. Do not be surprised if you are more short-tempered than usual on a fasting day.
Keep it modest. Do not pile up extraordinary spiritual expectations on yourself. The fast is not a bargaining chip. You are not buying an answer. You are placing yourself, hungry and ordinary, before a Father who already sees you, and asking him to do what only he can do.
Fasting together and in marriage
Fasting has a corporate dimension in Scripture. Joel calls the whole people to turn to God with fasting. In Acts 13:2-3 the leaders of the church fasted together and the Holy Spirit spoke. 1 Corinthians 7:5 treats fasting in marriage as something done by consent for a season, followed by coming together again, and it warns that Satan can exploit a lack of self-control.
That last verse is worth sitting with. Paul is not anti-fasting. He is anti-unilateral deprivation. A spouse who announces a fast and withdraws is not fasting; they are imposing. The rule is consent. Agree on the season, agree on the end, and return to normal. A church fast should be announced with clear dates and no coercion.
Corporate fasting can be powerful precisely because it removes the secrecy problem's easy escape. When everyone knows, the temptation is to perform. The safeguard is the same as in private: aim the fast at God, not at the group. Keep the day's tone toward worship and mercy rather than toward who is fasting the hardest.
Fasting and the rest of obedience
Isaiah 58 is the necessary correction to any fasting practice that becomes detached from life. Israel's fast was technically observant and morally hollow. God's rebuke is not that fasting is bad but that fasting without righteousness is a sham. The fast he chooses is bound up with loosing chains, feeding the hungry, and housing the homeless.
That does not mean every fast must include a charity project to count. It means the direction of your life during a fast should be consistent with the God you are seeking. If you spend the day fasting and sniping at family members, the fasting is not the problem; the heart is. If you skip meals and ignore the poor, Isaiah has words for you.
The connection runs the other way too. Mercy can show us our need for God and drive us to prayer, and fasting can make us more attentive to the needs around us because we are less occupied with ourselves. The two are meant to move together, a life turned toward God and toward neighbor, sustained by quiet dependence on the Father who sees in secret.
Biblical fidelity check
What Matthew 6:16-18 establishes is clear. Jesus assumes his disciples will fast, and he forbids fasting as a performance for human approval. He promises that the Father, who sees in secret, will reward. The passage does not establish a required frequency, duration, or diet. It does not say fasting earns forgiveness or guarantees any particular answer to prayer. It does not make fasting mandatory for salvation or for every believer's weekly routine. It addresses motive and manner, not mechanics, and it leaves the form to wisdom and circumstance.
A common misreading turns the passage into a prohibition on anyone knowing you fasted. That is not what it says. The issue is aiming at notice. A church that calls a corporate fast is not violating Matthew 6; a person who brings the fast up to be admired is. Another misreading treats the reward as a formula: fast secretly, and God owes you a result. But the text commends the secrecy, not a technique, and God remains free. Faithful Christians differ on how often and how long to fast, and Scripture does not settle that question for them.
Other passages that speak to Matthew 6:16-18
The rest of Scripture fills in what Matthew 6 assumes. 1 Corinthians 1: Called, United, and Boasting in the Lord shows a congregation whose life together had to be reoriented away from human approval. 1 Corinthians 10: Warnings and Freedom deals with appetite, discipline, and the freedom to abstain or partake for the Lord's sake. What Does 1 Corinthians 1:10 Mean? Context, Theology, and Application and What Does 1 Corinthians 1:9 Mean? Context, Theology, and Application both touch the unity and calling that make a shared fast possible. Read them alongside Matthew 6 and the practice stays anchored in the church rather than in private technique.
Frequently asked questions
Do Christians have to fast?
Scripture never commands a universal minimum of fasting, and no one is saved or justified by fasting. But Jesus says in Matthew 6:16, "Moreover when you fast, don't be like the hypocrites, with sad faces," which assumes his disciples will fast rather than treating it as an optional extra for the especially devoted. The New Testament church fasted in Acts 13:2-3. So fasting is expected as a normal spiritual discipline, but its frequency, length, and form are left to wisdom, health, and circumstance rather than fixed by command.
How long should a fast be?
Scripture gives examples rather than a rule. Many fasts are one day. Some last longer. Jesus fasted forty days in the wilderness before his temptation, which is a unique and extraordinary case, not a template for imitation. For most people the honest starting point is a single meal or a single day. Build from there only if you are healthy and it is proving fruitful. Extended fasts from food should not be attempted without medical counsel, and they are never a measure of spiritual maturity.
Is fasting from something other than food legitimate?
Setting aside a legitimate pleasure for a season to seek God is a real discipline, and many believers do it when health prevents fasting from food. But be honest about the difference. The biblical examples of fasting are about food, and calling a media break a fast can blur that. If you can fast from food safely, food is the ordinary practice. If you cannot, a modified fast offered to God is a reasonable accommodation, not a lesser Christian life.
