Definition of Fasting

Medically:
Glucose  is the body's primary fuel source and is essential for the brain's functioning. When denied glucose for more than 4–8 hours, the body turns to the liver  for glycogen, a storage form of glucose, to be used for fuel. A process called glycogenolysis converts glycogen into a usable form of fuel. At this point, the body also uses small amounts of protein to supplement this fuel. This fuel will last for up to 12 hours before the body needs to turn to glycogen stored in muscles, lasting for a few more days. If glucose is still denied at this point, muscle wasting is prevented by temporarily switching to fat as the fuel source, meaning fat is converted into ketone through catabolism. Ketones, while not sugars, can be used by the brain as a fuel source as long as glucose is denied.

Spiritually:
Today’s contemporaries are desperately trying to find a new spiritual identity. We have surrounded ourselves with a plethora of techno-gizmos that furnish an illusion of being in control. The feeling of mobility provided by computers, TV and internet are able to hide the powerlessness we have over our own inner will and emotions.

It’s time for a change.

At the start, it is going to hurt.

Fasting is a knife that cuts away superficiality, getting to the bone. Effective, because it is able to break up daily patterns upon which you have become so dependent. When those patterns of pleasure are removed, you are left with your own internal resources. If those resources are bankrupt, then during fasting, you will come face to face with a vacuum that only God can fill.

Fasting accomplishes two purposes. First, it will reveal how much the flesh has taken control of your emotions. And secondly, it will serve in breaking the flesh’s hold upon the will.

During fasting, patterns of living are broken. Fasting can be an oasis of spiritual refreshment in a life that has become a desert of uselessness. A spiritual desert that has been left in the wake of selfish materialism.

Fasting is not something which we are offering up to God, but, instead, it assists in offering ourselves up to God (Rom. 12:1-2).


(From Wikipedia & http://www.freedomyou.com/fasting_book/spiritual%20fasting.html)