If your want to know about fasting from a spiritual point of view, keep reading...
According to some religions, like Hinduism, fasting is an important way to purify and achieve grace. It´s not an obligation, however it shows respect. Sometimes fasting involves just eating one meal a day, and in other cases, just abstaining from one meal.
"The most commonly-observed fast, Ekadashi, is practiced approximately twice a month, on the eleventh day of each ascending and descending moon."
Fasting also allows the digestive organs to obtain some rest and cleanse all the body's mechanism. This leads to the feeling of lightness in the body, clarity in the mind and an increase in energy. One is said to obtain spiritual benefits through fasting.