Everything Under the Moon

can anyone tell me the purpose of fasting?
I've read a few things but none of it was very informative.
none of my books really talk about it either.

I can think of a couple of reasons.
1) Fasting can be used as a way of walking in another's shoes. Muslims fast during Ramadan for this reason. If you understand what it is like to live without food you appreciate what you have more.
2) Fasting (properly) helps your body rid itself of toxins, thus it's used for cleansing and purification. Just be careful, because simply not eating is very unhealthy for you. If you want to go on a fasting diet for detox reasons talk to a healthcare practitioner for advice.