Jesus didn't say IF you fast. He said WHEN you fast. It is a requirement for all Kingdom Citizens to fast because there are some things you cannot get done without fasting.

Moreover, when you fast, do not be like the hypocrites, with a sad countenance. For they disfigure their faces that they may appear to men to be fasting. Assuredly, I say to you, they have their reward. – Matthew 6:16 NKJV

One day Jesus’s disciples came up to Jesus upset because they couldn’t cast a demon out of a boy. Jesus told them that there are certain demons that cannot come out expect with the power that is manifested through prayer and fasting!  For kingdom citizens to pack this kind of power they MUST fast in the spirit or It's just another religious activity.

However, this kind does not go out except by prayer and fasting.” Matthew 17:21

Fasting in God's Kingdom is not about starving yourself to get God's attention, it's about quieting your flesh so you can hear His voice more clearly. When you fast, you turn down the noise of this world — its appetites, its distractions, its cravings — and you turn up your sensitivity to the Spirit. It’s not a punishment, it’s a positioning. In fasting, your spirit takes dominion over your body, your authority sharpens, and your anointing grows heavier. The Kingdom doesn't move by might or by willpower, but by men and women who have learned to live not by bread alone, but by every word that proceeds from the mouth of God.

Jesus tells us not fast outwardly, but to fast inwardly so the Father can reward us with power.

But you, when you fast, anoint your head and wash your face, so that you do not appear to men to be fasting, but to your Father who is in the secret place; and your Father who sees in secret will reward you openly. Matthew 6:17-18

If you fast in the flesh, you get no results.  All you get is hungry and miserable.  If you pray in the flesh, you get no results.  All you do is wear yourself out.  God can't do a thing for you if it's not His realm. Only in the realm of the spirit will fasting work.

The kingdom of God is not meat or drink but righteousness joy peace in the holy spirit.  It’s not about what you eat but about how you eat. It’s about not allowing yourself to be ruled by your appetite.

You can fast for external purposes and that’s ok and its good for you.  But kingdom citizens fast for internal purposes. For better activation and volume of the kingdom.

A man who fasts – leaving off all those things his appetite improperly craves – does a good thing. But the Kingdom Citizen who is fasting from his own desires and his own will and who feeds upon Gods will alone, does far better.

The kingdom is a real spiritual world. Fasting increases your compacity to receive spiritual power. Here is an example, imagine the Spirit flowing through a pipe that runs straight down your center being.  Food is like gunk, it makes the hole in that pipe smaller for the Spirit to flow through. The spirit still flows through it but it’s very restricted. Fasting is like drain-o. It flushes out all the distractions and makes you solely, completely open to God.

The first act Jesus did after he got baptized and started His ministry was fast because fasting activates the kingdom. How are you going to overcome the power of that demon if you can’t overcome the power of your belly.

For many walk, of whom I have told you often, and now tell you even weeping, that they are the enemies of the cross of Christ: 19 whose end is destruction, whose god is their belly, and whose glory is in their shame—who set their mind on earthly things. Philippians 3:18-19