So we fasted and besought our God for this: and he was intreated for us. ~Ezra 8:23 KJV
Many times when fasting is mentioned in the Bible we need to notice where and when it was written. There is a difference between Old Testament and New Testament fasting.
Before the cross, people fasted because Jesus had not yet satisfied the payment that was owed. There was no sacrifice made so there was a certain sacrifice that was acceptable to God. People were seeking an answer from Him so they would subject themselves to a certain suffering and he was faithful to answer.
God is still faithful to answer us in the New Testament life but now there was a sacrifice that Jesus made for all of us. He made a payment that was owed with his own blood. He suffered, died and was buried for us. No sacrifice is needed now. When a New Testament believer fasts these days he is fasting to build himself up. He is bringing his flesh into submission to the Spirit of God. Before the person accepted Jesus into his heart the body ruled. Whatever it wanted was what was priority. Now it needs to be trained to listen to the Spirit of God. That is why we fast now a days. We need to bring our body into submission but also so we can hear the Lord speak to us more clearly.
And Jesus said unto them, Can the children of the bridechamber mourn, as long as the bridegroom is with them? but the days will come, when the bridegroom shall be taken from them, and then shall they fast. ~ Matthew 9:15 KJV
When Jesus walked with the disciples there was no need to fast because you could speak to him directly. But after he was crucified they needed to fast to put their flesh under subjection to be able to hear the Lord speak to their hearts clearly. If you have ever fasted and started to experience shakiness or head aches, it’s your body trying to tell you to go and eat. But when you speak to your body with authority you are making it do what you want it to do. It is so powerful! You will be training yourself to hear the Lord clearly and your body is obedient to what you tell it to do. Not the other way around.
So when you fast remember you are bringing your body in to control of what the Spirit wants instead of what the body wants. You can do this! You are an overcomer!