Oh you who believe, fasting is prescribed for you as it was prescribed for those before you so that you may attain God-consciousness. [Qur'an 2:183]
Fasting produces physically measurable conditions. It also produces conditions not yet scientifically defined that we may describe as spiritual or mystical.
Perceived reality changes with the physical conditions prevailing within a person. To enjoy something one day and be bored or even repulsed by the same thing another day is not unusual.
When we fast, our perceptions change as the body responds to reduction in levels of energy, mental activity and functions dependent on nutrients. A satiated person thinks in a particular way and formulates theories, understands facts and reaches conclusion quite differently from that of a fasting person.
Fasting produces changes in how we sense, understand and respond to perceived reality. What we see and how we act changes when we fast. When we end the fast, we remember and appreciate the effects, but cannot easily reproduce the state achieved.
Even more significant is the process of spiritual awareness that fasting can evoke. The manner in which fasting stimulates such God-consciousness is difficult to explain or even describe. A way of looking at this process is to consider human reality as extending to two extreme conditions, one of complete rebelliousness and one of complete submission.
As a person becomes satiated, then glutted, he feels ever more independent, self-sufficient, even proud and arrogant. Affluence, unchecked, can generate these states.
By contrast, as a person becomes hungry and needy, he feels dependent, insecure, humble and submissive. How common it is for persons in need of help – food, shelter, safety, any basic need – how common it is for us to turn to God at such times of need.
Fasting simulates an “artificial” state of need. It produces a spiritual condition that cries out for God. This is a natural process that God has ordained. Thus, we fast for God.
Beware that thou forget not the LORD thy God, in not keeping his commandments, and his judgments, and his statutes, which I command thee this day: Lest when thou hast eaten and art full, and hast built goodly houses, and dwelt therein; And when thy herds and thy flocks multiply, and thy silver and thy gold is multiplied, and all that thou hast is multiplied; Then thine heart be lifted up, and thou forget the LORD thy God, which brought thee forth out of the land of Egypt, from the house of bondage . . .[Deuteronomy 8:11-14]