In many spiritual traditions fasting is a requirement. Sometimes it is for a certain period of time, like the daylight hours of Ramadan for Muslims or before some celebrations for Earth Religions. At other times it is part of repentance when some transgression has been committed.
Not eating anything as a form of protest is a hunger strike, not a fast. Not eating to lose weight is a bad diet, not a fast. A fast is a time of abstaining from all food, or just certain foods; all drink, or just certain drinks. It sets aside dietary pleasure in order to grow spiritually.
A fast should have some spiritual benefit for the one doing it since it is primarily a spiritual discipline. One should know the purpose or goal of the fast before entering the period of fasting; otherwise it can be simply a legalistic requirement that leads to bitterness or superficial faith. The fast will be a time when routines are upset within the body, but if one only thinks about the physical hunger then there will be no spiritual gain from it. The feelings of hunger should lead one to focus more acutely on prayer and meditation and the reason for the fast. Those reasons can range from doing penance to increasing one’s mindfulness of God in the world.
If you have not tried fasting, I would encourage you to try it. Start small and with a specific purpose. Don’t talk about your fast in spiritual arrogance; no one needs to know. Fast from only those things that you can abstain from safely; diabetics and others need to be careful and not go against medical advice. Do it willingly. It is not a legal requirement. Let the fast change you.