At some point in their spiritual quest, seekers are generally confronted with the question of ‘fasting’. Some paths recommend fasting as a method to lighten the heaviness of the ‘earth consciousness’ and make the being more receptive to higher vibrational energies. Some point out that fasting aids in achieving a ‘vision quest’. Some practice fasting to habituate the body to become less reliant on the material energy and switch its source of energy to higher vital and eventually spiritual realms. In the daily ordinary life, people undertake various forms of ‘fasting’ as a means of gaining control over their weight, although they call it in that context ‘dieting’.
There is no doubt that fasting changes the energetic flow of the being, that one feels lighter and more in tune with the vital and mental energies and less subject to the downward pull of the physical body. There is also no doubt that in certain contexts, the achievement of a ‘vision’ is aided by the practice of fasting.
It is, however, also true that the physical body requires adequate nutrition and that fasting, if practiced over the longer term rather than as a very short-term exercise, can undermine the physical substance and stability, and can create a nervous condition of the being that is not healthy for the spiritual practitioner who is not simply trying to abandon the outer life of the body.
Sri Aurobindo notes: “It is a fact that by fasting, if the mind and the nerves are solid or the will-force dynamic, one can get for a time into a state of inner energy and receptivity which is alluring to the mind and the usual reactions of hunger, weakness, intestinal disturbance, etc., can be wholly avoided. But the body suffers by diminution and there can easily develop in the vital a morbid overstrained condition due to the inrush of more vital energy than the nervous system can assimilate or co-ordinate. Nervous people should avoid the temptation to fast, it is often accompanied or followed by delusions and a loss of balance. Especially if there is a motive of hunger-strike or that element comes in, fasting becomes perilous, for it is then an indulgence of a vital movement which may easily become a habit injurious and pernicious to the sadhana. Even if all these reactions are avoided, still there is no sufficient utility in fasting, since the higher energy and receptivity ought to come not by artificial or physical means but by intensity of the consciousness and strong will for the sadhana.”
“The first thing I tell people when they want not to eat or sleep is that no yoga can be done without sufficient food and sleep (see the Gita on this point). Fasting or sleeplessness make the nerves morbid and excited and weaken the brain and lead to delusions and fantasies. The Gita says, yoga is not for one who eats too much or sleeps too much, neither is it for one who does not eat or does not sleep, but if one eats and sleeps suitably — yuktahari yuktanidrah — then one can do it best. It is the same with everything else. How often have I said that excessive retirement was suspect to me and that to do nothing but meditate was a lop-sided and therefore unsound sadhana?”
Sri Aurobindo, Integral Yoga: Sri Aurobindo’s Teaching and Method of Practice, Chapter 10, Difficulties in Transforming the Nature, Food, pp 314-317