When we fast we are telling God that He is the most important thing in our life and that we are dependent on Him for our substance.
Our God is a jealous God and He wants us to realize how much He matters to us. He already knows our hearts and our priorities, so by giving up what we love to eat or to do, proves to ourselves, that we really love the Lord.
Although fasting in Scripture is almost always a fasting from food, there are other ways to fast. When we fast without food and water to focus our hearts and minds on God and His purposes, we are humbling ourselves and tell God that He matters more than anything else. This is because we intentionally cut off our energy source- food and rely entirely on God for His sustenance of power.
It helps us to think more deeply and form a greater connection with God by showing our dependence on him.
If we are willing to give up things that matter to us and spend that time interacting with God instead, we are putting him at a higher priority in our lives than these other things.
As we fast we are putting God before everything else including food. This shows God we are reliant on him to fully sustain us!
You are clearing away things that rob you of precious time spent on those things that shift you away from a God centred focus and making God the central focus by eliminating them .
Eliminating all distractions and to focus on Him