Answer:
The first thing to remember about fasting is why Jesus did it. Here’s the situation: Matt 4:2-4 After fasting forty days and forty nights, he was hungry. The tempter came to him and said, "If you are the Son of God, tell these stones to become bread." Jesus answered, "It is written: 'Man does not live on bread alone, but on every word that comes from the mouth of God.'"
So Satan wants him to break his fast by tempting him to display his power. And Jesus quotes Moses: "Man shall not live by bread alone, but by the Word of God." This verse is why we fast (and why we give too). And in so saying, Jesus was modeling for us this principle: people who live by faith, must train themselves to focus on God-realities as the highest realities by denying themselves physical satisfaction sometimes.
Paul tells us in Col 3:1-2 "Since, then, you have been raised with Christ, set your hearts on things above , where Christ is seated at the right hand of God. 2 Set your minds on things above , not on earthly things." How do you set your mind on things above? How do you take you mind off of earthly things? I mean, God made you from the dust of the earth, how exactly are you – fleshy and carnal and physical and corporeal creature – going to do that? This is not going to be easy! But we have been brought to believe by Christ that ultimate reality is not now, but coming later.
Cor 7:29-31 says, "What I mean, brothers, is that the time is short. From now on those who have wives should live as if they had none; 30 those who mourn, as if they did not; those who are happy, as if they were not; those who buy something, as if it were not theirs to keep; 31 those who use the things of the world, as if not engrossed in them. For this world in its present form is passing away ." How do we live like that? There is only one way: You have ruthlessly develop habits in your life that are designed to take your eyes off of physical BREAD and onto spiritual BREAD that comes only from your Creator and Redeemer.
The way is through disciplined, intentional, artificial desperation. You build into your life, habits that create physical desperation, to remind your heart that is wasn’t built for this earth – it’s home is elsewhere. Giving is intentional, artificial, financial desperation/ Fasting is intentional, artificial, physical desperation. Why would a person go hungry when they don’t have to? For the same reasons that we give… to train our hearts to focus on God, to train our hearts that man does not live by bread alone…
This is the lesson in fasting… you get intentionally hungry, so you create space in your heart for God to show up. To say, God I’m hungry and my body needs food, but I need you MORE. My body could die, but without you giving me life, my soul dies. So SOUL BREAD is the bread I really need.
So when should you fast? There are seasons and reasons for fasts in Scripture which fall under these main ideas:
FOR DIRECTION: 2 Chron 20:3 Alarmed, Jehoshaphat resolved to inquire of the LORD, and he proclaimed a fast for all Judah. NIV (when three invading armies threaten their survival)
FOR CONFESSION/REPENTANCE: 1 Sam 7:6 On that day they fasted and there they confessed, "We have sinned against the LORD." NIV (Ark stolen by Philistines and returned)
FOR MOURNING: Neh 1:4 When I heard these things, I sat down and wept. For some days I mourned and fasted and prayed before the God of heaven. NIV (Holy City is vulnerable and in shambles)
FOR HUMILITY Ps 35:13 Yet when they were ill, I put on sackcloth and humbled myself with fasting. NIV (David prays for his enemies)
FOR PETITION/POWER: 2 Sam 12:16 David pleaded with God for the child. He fasted and went into his house and spent the nights lying on the ground. NIV (Bathsheba’s love child of adultery is dying)
ALL OF THE ABOVE: Dan 9:3-4 So I turned to the Lord God and pleaded with him in prayer and petition, in fasting, and in sackcloth and ashes. I prayed to the LORD my God and confessed:
Fasting turbo charges prayer. The persistent widow is heard because of her persistence. Sometimes our prayers are unanswered because frankly, we don’t really care enough to mention them more than once. But what if we were pressed in, devoted, desperate, pleading? How would we show that to God…? How about going without food? It's not a work we do for God, so much as something we do for us, to train and focus a heart of faith.
So if you have never done this there’s a great book on my shelf called “God’s Chosen Fast” that can get you started. Some common misunderstandings about fasting:
"I can’t go without food for a day without hurting myself." Actually the average person has reserves to go many days without food. You only risk damage to yourself after many weeks without food.
"Fasting will give me a head ache which means I’m getting sick." Actually the pains you experience fasting will be mostly be your body’s demand for caffeine, tea, coffee or refined sugars.
"I can’t work while I’m fasting." Actually you can work while you’re fasting, unless you have a job that involves deep physical labor. At the end of a ten day liquid fast I actually played basketball – which I wouldn’t recommend – but I made it. If you take it easy, most normal working tasks will be possible.
"God made us to need food, so how can it be helpful to go without it?" You can be addicted to good things. People are addicted to sex all the time. We can be addicted to food and the pleasure it gives. So that’s all part of the exercise: "God I need food, but I need you more than food." Fasting will often reveal the hold that things have on you, crutches and idols, not just food. Some addictions more insidious than alcohol or drugs, and they may be an issue for you and you don't know it. LIke an addiction to control, to popularity, to reading, a hobby, sleep, work, pornography, you name it.
Practically, I suggest you consult your doctor first if you have any risky medical conditions like diabetes or hypoglycemia. I also suggest you start with a single meal. When you work your way up to a full day fast, you will experience severe hunger pains the first day. These go away almost completely by the third day. You experience a lot of discomfort because your body is getting rid of toxins that have built up for years. Poisons come out all over the place, your tongue may develop a coating, your breath will be very bad and even your skin will feel unusual. You’ll probably experience a head ache if you drink a lot of coffee or tea and other withdrawal symptoms. After these pass, you may get dizzy so be ready to ease off on your schedule and drink lots of water.
