The answer
Fasting is first and foremost an exercise of love for God, renewing of the heart toward God, and restraining the influence of one's will toward God's will. Fasting redirects our inner selfish pleasures to higher spiritual enhancement. Food satisfies one of the basic survival needs. However, it can also be a source of gluttony, over-indulgence, greed, and neglect of those in need. What we are denying when we fast is not the need to eat but the demand of immediate satisfaction, being led by the eyes and stomach, not the spirit. When we fast, we return to our basic needs and focus on the greater need to be satisfied with Christ Jesus our Lord. We fast by eating the simple foods produced in the earth to satisfy hunger. We ought to use the money saved to give alms and remember those in need, who not by choice, but rather by circumstance, are nourished by fasting portions throughout the year. In addition, prayer is a necessity to accompany fasting and almsgiving, as Archangel Raphael declared, "Prayer is good with fasting and alms and righteousness" (Tobit 12:8). Not only the Church Fathers, but the Holy Scripture also teaches us the importance and need for fasting from foods. The Church has set days, seasons, provisions, and guidelines for fasting, that we all worship together, united in our fasts and understood by the congregation, for example, Queen Esther, the Three Holy Youth, the Ninevites, and many others: "So we fasted and entreated our God for this, and He answered our prayer" (Ezra 8:23).Please encourage your son to read: "The Spirituality of Fasting" by Pope Shenouda III: http://tasbeha.org/content/hh_books/fasting/index.html.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)