Is fasting good for your physical well-being, your spiritual well-being or your holiness? Yes! and No!
It can be beneficial for our physical balance if we have a regular fast. It allows our bodies to detoxify. It can help prevent obesity by allowing you to subjugate your desires for excessive food intake, but it is not a recommended means to lose weight. (Isaiah 58:8-11). However, if overdone then obviously the body will weaken and eventually, if prolonged too much, result in bodily damage or even death. (Rule of thumb: 3 minutes without air; 3 days without water; 30 days without food.)
Fasting from physical input allows us to focus on spiritual food, such as feeding our understanding of our own authority and power given to us as part of our position in God. We will benefit from fasting by our focus away from ourselves and focus on others. This will give us an outward focus compared to self focus. As “God is Love”, then as we are made in His image and likeness, then we too should be Love. This is not a feeling, but is to be the self-sacrifice that benefits others. Thus our sacrifice of food in fasting should be to the benefit of others.
Matthew 17:21 “However, this kind does not go out except by prayer and fasting.” This verse implies that said prayer and fasting must occur before the actions are needed. This kind of fasting is to keep us attuned to our rightful position of power and authority and not let ourselves be weakened by doubts.
Fasting does not increase our holiness. We are already holy, (set apart, different, unique), before God by the decree God made by making Adam/Eve in His image and likeness and giving them dominion over the rest of creation, however fasting can help us to improve our understanding of our holiness as the result of focusing on that which we already have.
God’s Fasting Preference:
In (Isaiah 58:6-7) God’s chosen fast is to loosen the bonds of wickedness, undo the bands of the yoke, free the oppressed and break every yoke. Feed the hungry, help the homeless and cover the naked. (Compare Isaiah 61:1-3 & Luke 4:16-21.)