Fasting must have been an integral part of the spiritual life for Jesus to give instructions on it. He did not try to diminish or dissuade disciples from fasting, but His instructions were to help them do it with the right attitude.

There are many people whose religion is external, for show, who hypocritically practice their religion for the eyes of man and not for the pleasing of God. So when they fast, it must be done with certain cues that signal to others that they are pious. Jesus says their only reward will be the attention they receive from men.

Jesus says to fast in a way that God sees and He will reward the person.

Does all fasting have to be done in secret? No. Jesus fasted and so it was not secret. The disciples of John fasted and it was pleasing to God. This was not secret. The early church fasted when having to make big decisions, Acts 13:2,3; 14:23. The fasting was for spiritual purposes and it was not private. Doesn’t this contradict Jesus’ words? No. We need to learn to recognize the difference between visible faith done to please God and visible religious acts done to please men.  Jesus did not suggest that Christians practice all of their righteousness in private otherwise how would the world see disciples being salt and light on a hill? Whether it is giving, praying, or fasting, the motive must be to please God and not men. God knows the difference and only one does He reward. So always check the motives for why you fast.

Does all fasting have to be for spiritual purposes?  No. Abstaining from food can be a purely health maintenance choice. There are good reasons to hold off on eating because of the physiological benefits it brings. The benefits are so clear that it must be part of the Creator’s design. Fasting places the body in a reparative or regenerative state where the body itself begins to heal itself on the cellular level. Toxins are eliminated. Inflammation is reduced. The immune system gets a kickstart. Plaque amyloids in the brain are broken down and removed. I can’t name all of the benefits of fasting from food but they are many. So there are good reasons to have fasting from food, drinking only water, as a part of body health maintenance. I would add the caveat that even though the purpose may not be the private seeking of wisdom or drawing near to God, still a person must maintain their faith by being humble and avoid the vain pursuits of the flesh.

So if it sounds like I’m contradicting Jesus, I’m not.  Whether the fasting is for spiritual tuning or for physical health benefits, everything should be done in the name of the Lord. Keep your faith. Know that the devil will use all such things to ruin you if he can. In all things, draw near to God. Always check the motives and avoid vanity. As you pray public prayers, check the motive and do it for God. When you give and men see, always check the motive and do it for God. God knows. And when you pray, check the motive and do it for God.