Gifts of Yoga:
The Psychology of (Food) Craving
from the scriptures,
and how Yoga helps overcome this
1) Hlada, the Non-sensual pleasure
People sometimes crave food even when not hungry due to stress, emptiness, boredom and a variety of other unwholesome mind states. The well known meditation teacher, Gil Fronsdal, mentions this in his dharma talk titled "Insight and concentration practice" (at time 20:10). He says that when there is a lack or emptiness within us, there is only so much one can do to try to fill it externally using "comfort" food or other means. However, when one tries to fill it from inside, through meditation (or other yogic practices), then it is far more effective in filling the void.
Comparison of joy from the deep state of Samadhi to an underground spring that bubbles up in a lake
The Buddha, uses similes to describe Samadhi, the deep settled state of mind in which one merges with the object of focus and there is no distinction between the subject (oneself) and the object of mental focus. Patanjali also describes this state as the ultimate state reached through Yogic practices. The Buddha describes the joy from a settled state of mind as being non-sensual and he uses the example of a underwater spring that bubbles up, to describe the sensations that arises and suffuses the body with joy. He uses the term non-sensual pleasure to distinguish this pleasure that comes from meditation, from the sensual pleasure, like eating, that comes from the senses. In Sanskrit this word is called "Hlada", or out-worldly pleasure that is not obtained from worldly objects via the senses.
When one starts doing Asanas, especially with awareness of the prana using bandhas to channel it and mudras to access it, there is a deep sense of joy and rest. Then little by little, the sense of lack vanishes and the contentment and lightness (Angha Laghavam) that comes from these states is much more valuable than the temporary gratification that comes from eating excessively, which then results in the body feeling heavy and bloated and the mind dull.
2) Craving: The analogy of a person with leprosy and the skewed perception of being pleasant
The Buddha, as previously said, used similes to illustrate various behaviors of the mind. For craving, he uses a rather gruesome analogy of a person with leprosy (a skin disease caused by bacteria that results in sores and itching) cauterizing his lesions over a fire to relieve the itch. The Buddha says tells his disciple Magandiya in the Magandiya sutra,
"In the same way, Magandiya, sensual pleasures in the past were painful to the touch, very hot & scorching; sensual pleasures in the future will be painful to the touch, very hot & scorching; sensual pleasures at present are painful to the touch, very hot & scorching; but when beings are not free from passion for sensual pleasures — devoured by sensual craving, burning with sensual fever — their faculties are impaired, which is why, even though sensual pleasures are actually painful to the touch, they have the skewed perception of 'pleasant.'"
3) Food and yoga
In Yoga, especially Hatha Yoga, it is believed that a healthy flow of prana is necessary to maintain a healthy body and mind. To maintain a healthy flow of Prana, one needs to have a healthy Agni (fire) in the body. Just as dumping a heap of material over a fire, douses it, eating a lot of food also douses the fire in the body. The "unburnt" food accumulates in the body as toxins causing disease. That is why all yogic texts talk about eating a moderate diet. It is said that a Yogi eats one meal a day. While one meal a day could be very difficult for most of us, considering the frantic pace and stress in our lives, two meals a day is considered a good optimum for people who are serious about pursuing yoga, be it asana or meditation or study of the scriptures. Depending on one's Dosha one has to adjust the quantities and frequencies. For a vata dominant person, for example, it may make sense to have smaller meals more than twice a day.
4) Conclusion: Overcoming food craving
Overcoming food craving by a force of will is a very difficult task. But, by tapping into the feelings of lightness (angha laghavam), well being and joy that come from yoga, one's body eventually will be able to turn toward the lasting pleasure offered by yogic practices and away from the temporary gratification offered by binging on food.