Fasting seems to be quite a powerful spiritual practice. I think this is because by denying the body food you are working on craving at it’s most fundamental level.
All suffering is caused by desire or wanting. You suffer because you either want something to happen that isn’t happening or you don’t want something to happen that is happening. It all comes down to addiction. We are all addicted to getting what we want whether that is food, drugs, entertainment, or not-being-hurt.
I think that because food is such a fundamental need that all other desire is derived from it. Therefore by denying yourself food you are working on desire in all its forms.
Hunger pangs are good as anchors. When you are fasting and are being attacked by the desire for food meditate upon the physiological manifestations of that hunger which are the hunger pangs. After a while you will be able to disconnect the hunger pangs from the desire for food. The hunger pangs become phenomena, stuff that is happening like any other stuff that is happening. This is liberating because now you are no longer dominated by them. No longer must you act in a particular way because your belly grumbles.
I’ve also found that by using hunger as a spiritual practice it stops becoming something that causes me to be antsy. Instead – because I become mindful of the hunger – it stimulates peace.
Also fasting is healthy. According to a Horizon documentary I watched recently when you fast your body stops replacing cells and starts healing them. That is of course if done properly. I’ve only been doing fasts of 24 hours every Saturday for the last few weeks and I’ve noticed I’ve been feeling generally better for the rest of the week.
In a fast I find that there are periods of clarity where I experience a peace and stillness far greater than that which I normally experience and periods where I am shaking and feel quite low. I think this is another one of the reasons why fasting is such a powerful spiritual practice and is a practice in almost all spiritual traditions.
The samsara, the oscillation from pleasant to unpleasant is more noticeable when one is fasting. It occurs at a quicker rate. This shows us the temporary nature of pain and pleasure. Now I am feeling very hungry, my belly is hurting but 5 minutes ago I was alert and felt serene. That is the lesson of life being taught far more frequently than usual.