The Collected Works of Mahatma Gandhi -Vol. XVII, p. 104, 20-3-1920
Fasting in Satyagraha has well-defined limits. You cannot fast against a tyrant, for it will be as a piece of violence done to him. You invite penalty from him for disobedience of his orders, but you cannot inflict on yourself penalties when he refuses to punish and ren¬ders it impossible for you to disobey his orders so as to compel infliction of penalty. Fasting can only be restored to against a lover, not to extort rights but to reform him, as when a son fasts for a parent who drinks. My fast at Bombay, and then at Bardoli, was of that character. I fasted to reform those who loved me. But I will not fast to reform, say, General Dyer who not only does not love me, but who regards himself as my enemy.
The Collected Works of Mahatma Gandhi -Vol. XVIII, p. 420, 12-4-1924
What you say about fasting is quite true. It has no absolute value and it certainly does not produce the slightest spiritual effect if the motive behind it is not really spiritual. Fasting with a mixed motive ends with purely material results. But fasting for the sake of unfoldment of the spirit is a discipline I hold to be absolutely necessary at some stage or other in the evolution of an individual. I always considered Protes¬tantism to be deficient in this particular. Every other religion of any importance appreciates the spiritual value of fasting. Crucifixion of the flesh is a meaningless term unless one goes voluntarily through pangs of hunger. For one thing, identification with the starving poor is a meaningless term without the experience behind. But I quite agree that even an eighty days' fast may fail to rid a person of pride, selfishness, ambition and the like. Fasting is merely a prop. But as a prop to a tottering structure is of inestimable value, so is the prop of fasting of inestimable value for a struggling soul.
My Dear Child, p. 85, 20-8-1926
Fasting should be inspired by perfect truth and perfect non-violence. The call for it should come from within and it should not be imitative. It should never be undertaken for a selfish purpose, but for the benefit of others only. A fast is out of the question in a case where there is hatred for anybody. But what is the inner voice? Is every one capable of hearing it? These are big questions. The inner voice is there in every one of us, but one whose ears are not open for it cannot hear it, just as a deaf person is unable to hear the sweetest of songs. Self-restraint is essential in order to make our ears fit to hear the voice of God.
Selected Letters-II, pp. 46-47, 30-10-1932
The fast has become the normal course of my life. It is the spiritual medicine applied from time to time for diseases that yield to that particular treatment. Not everyone can gain the capacity for it all of a sudden. I have gained it, if I have, after a very long course of training.