Question: "How to fast - what does the Bible say?"
Answer: The New Testament nowhere commands followers of Jesus Christ to fast. In fact, even in the Old Testament, the Jews were only commanded to fast on one day out of the year, the Day of Atonement (Leviticus 23:27, 29, 32). Any religious leader who commands a fast or restricts certain foods is doing so without biblical warrant. However, Jesus sometimes fasted (Matthew 4:2), and He assumed that His followers would also fast on occasion (Matthew 6:16–18; Mark 2:20). So, if fasting is something that Christians do, what is the proper way to fast? What does the Bible say about how to fast?
The Bible mentions different types of fasting. There is limiting yourself to a certain type of food (Daniel 1:8–14). There is fasting from food entirely (Daniel 10:2–3). There is fasting from food and water (Luke 4:2; Acts 9:9). There is also “fasting” from a certain activity, such as a husband and wife abstaining from sex for a predetermined period (Exodus 19:15; 1 Corinthians 7:5). With the different types of fasting in mind, how to fast depends greatly on what type of fasting you are doing.
Always ask God for wisdom (James 1:5) in regards to how and for how long He wants you to fast. Setting a time frame seems to be the biblical approach (Esther 4:16). Also, fasting should have a clear purpose. People in the Bible fasted and prayed because they wanted something specific to happen. They either wanted God to change them, to change their circumstances, or to reveal something to them. Ultimately, fasting is far more about focus than food. Fasting is taking your focus off of the things of this world in order to focus more on the things of God. Fasting can thus be a means of growing closer to God.
A note of caution concerning fasting: those with medical conditions, especially conditions involving dietary restrictions (diabetes, for example), should consult a doctor before fasting. Remember, there is no biblical command that followers of Jesus Christ must fast. Therefore, it is not wrong to take a medical condition into account when determining how to fast.
Also, it is good to examine your motives for fasting. Fasting is not about manipulating God. Fasting will not cause God to do something that is outside of His will. Fasting is about changing yourself to be in agreement with God’s plan and to be prepared to carry out your role in His plan. When you are deciding how to fast, it is crucially important to remember what fasting is all about—changing yourself, not changing God.