St. Seraphim of Sarov on Fasting:
“Fasting consists not just of eating rarely, but also of eating little. And not just in eating only one meal, but in not eating much. Foolish is the faster, who waits for a specific time [to eat a meal], but then at the time of the meal is completely consumed, body and mind, with insatiable eating.
In proportion to how the body of the faster becomes thin and light, so the spiritual life attains perfection and reveals itself in wonderful ways. Then the soul acts as if in an incorporeal body. Carnal feelings are shut off, and the spirit, released from the world, ascends to heaven and completely immerses itself in contemplation of the spiritual world.
Every day one should partake of just enough food to permit the body, being fortified, to be a friend and helper to the soul in performing the virtues. Otherwise, with the body exhausted, the soul may also weaken.”