Fasting is quite common in Jainism.. There are various fasts people take on, among which is atthai - no food or water for eight days or just no food for eight days.. I've done it once.. its quite similar to how its described in this article.

http://en.wikipedia.org/wiki/Fasting_in_Jainism

There are several benefits of fasting but primary reason to fast in Jainism is non-violence