Buddhism and Fasting
Buddhism came into existence in the midst of Hinduism. The founder, Siddhārtha Gautama, became enlightened and as part of his revelations discovered that that the ascetic excesses of Hinduism, which he was taught and lived with as part of his culture, were unnecessary. Since its founding the ideas, concepts, and practice of Buddhism have changed. Different cultures and the times it is practiced in each bring their own nuances to Buddhism. Beyond the core principles of the Four Noble Truths and the Noble Eightfold Path there are many ideas as to what the practicing of Buddhism means. Fasting thus is not considered a core principle or idea of its teachings. Even so, traditionally Buddhism is a practice that teaches moderation and austerity as part of living what is called the Middle Way. Siddhārtha Gautama did also suggest that monks, or bhikkus as they are called, should limit their diet after noontime.
Some Buddhists do fast to help focus on subsuming their bodily desires. This is done in part to work towards the ultimate goal of generally rising above all desire – hence ending suffering and thereby achieving Nirvana.
Devout Buddhist monks, in some traditions, live in communities that observe strict rules designed to focus attention on the Noble Truths and Noble Eightfold Path. In some cases food is only consumed in the morning, before noon, and fasting is practiced from noon until the following morning. In other communities and retreat centers fasting may be practiced for different lengths of time. Often these are water fasts that can last numerous days or even many weeks. This is done, along with other measures, to serve as an opportunity to sharply focus on align oneself with the Buddhist path in a way that cannon be done in normal, everyday life.
You can read one example of how fasting is viewed and practiced in one Buddhist tradition at UrbanDharma.org