Pope Shenouda III
Fasting that is not for God is invalid:
Some may fast on doctor’s orders. Another may fast to have a graceful body and good looks,. Both fasts are not performed for God and or spiritual gain. A third person may go on a hunger strike and not for spiritual aim or for God's sake. A fourth may forsake food in distress or despair. Non of these fasts can be considered genuine. Again, we reiterate by saying that any fast which is not for God and spiritual gain, cannot be considered a fast and is not accepted by God.