Why is fasting important?
Fasting is recommended as tapasya, austerity, because it helps us control our senses, and sense control is very helpful in becoming Krishna conscious. If our senses are out of control and unregulated, we won't be able to come to the mode of goodness, sattva-guna, which is required for making sure and steady spiritual progress. Fasting is also good for health because it gives the digestive organs a rest.
- Speaking on Bhagavad-gita 7.9, Vrindavana August 15, 1974:
"tapasya means to undergo voluntarily some inconveniences of this body. Because we are accustomed to enjoy bodily senses, and tapasya means voluntarily to give up the idea of sense gratification. That is tapasya. tapasya. Just like Ekadasi. Ekadasi, one day fasting, fortnight. That is also tapasya. Or fasting in some other auspicious day. That tapasya is good, even for health, and what to speak of advancing in Krishna consciousness. So we should accept this tapasya. . .There are many prescribed days for fasting. We should observe."
- Room conversation, January 25, 1977, Puri
Srila Prabhupada: ". . .More we have sex, more we have eating, more we have sleeping, that means I am entangled. The more we conquer over it, we are free. That we have to try. Whether I am in the clutches of maya or not can be tested—whether I am sleeping more, whether I am eating more, whether I am more sexually inclined. He can test himself. And bhakti means vairagya-vidya, to conquer over these three things. . . It is part of this education, spiritual education. And not to eat more than necessary. Then you'll not sleep more. You'll find, if you observe fast, you won't feel sleepy. Have you tested this?
Gargamuni: Yes. I can remember.
Prabhupada: Therefore ekadasi. One day or two days in the month he should practice fasting, and then he'll be able to conquer over these things."
Srimad-Bhagavatam, 1.17.38, Purport:
"Even from the economic point of view, such two fasting days in a month [ekadasi] in the state will save tons of food, and the system will also act very favorably on the general health of the citizens."
- From a lecture on Bhagavad-gita 6.16-24 in Los Angeles, February 17, 1969:
"Because in the beginning, because we are accustomed to eat voraciously, so don't try to eat less artificially. You eat. But try to minimize. Therefore there are prescription of fasting. At least two compulsory fastings in a month. And there are other fasting days. The more you can reduce your sleep and eating, you keep good health, especially for spiritual purposes. But not artificially."
- Path of Perfection, Chapter 4:
"As far as the body is concerned, there are four demands—eating, sleeping, mating, and defending. The problem with modern civilization is that it is trying to increase these demands, but they should be decreased instead. Eat what we need, and sleep when we need, and our health will be excellent. There is no question of artificial imitation.
And what is the result obtained by one who is temperate in his habits?
'When the yogi, by practice of yoga, disciplines his mental activities and becomes situated in Transcendence—devoid of all material desires—he is said to have attained yoga.' (Bg. 6.18)"
- Srimad-Bhagavatam, 7.12.23: "When because of disease or old age one is unable to perform his prescribed duties for advancement in spiritual consciousness or study of the Vedas, he should practice fasting, not taking any food."
Below are some things Srila Prabhupada has to say on this topic: