What is the purpose of fasting? To lose weight? To spend time with God? To deny ourselves?
Imagine that you're driving a car with two passengers. In the passenger seat is a loud, opinionated person. In the back is a wise, soft-spoken person. All you can hear is the person next to you, barking instructions. After a while you realise he is only looking out for himself, so you have your passengers swap places.
With the wise person in the front seat, perhaps you’ll get somewhere, but the loud one still shouts him down. Though you want to listen to your soft-spoken friend, you can’t hear him. Eventually you tell the backseat driver to be quiet for five minutes, so that you can listen. In those few minutes, you actually get somewhere.
I Fast to Train My Body
The driver represents your soul (mind, emotions, feelings). The loud person represents your body (flesh, selfish desires), and the soft-spoken person represents your spirit. Our spirit has been renewed by God and communicates with him. Before we are saved, we have our selfish desires in the front seat. Once we give our lives to Jesus, we switch our spirit to the front. Very often as Christians, we want to listen to our spirit but can't hear it over the voice shouting from the back. We need to tell our bodies to be quiet every now and then in order to hear our spirit. It needs to learn it is no longer in charge.
“Do not be conformed to this world, but be transformed by the renewing of your minds, so that you may discern what is the will of God—what is good and acceptable and perfect” Romans 12:2 NRSVA
This is why we fast, to train our body to take second place to our spirit and to the voice of God.
Our mind is a powerful tool. We need to get it fighting for us (in line with God's Word) and not against us (in line with our sinful desires). If we combine fasting with prayer and the Bible, we’ll be focusing on what God is saying while our body is having a time-out.