On such days they do not eat at all, eat once or make do with fruits or a special diet of simple food. Fasting in Sanskrit is called upavaasa . This explanation is supported by concepts in yoga and self discipline that the body should be made accustomed to pain and rigor, for this helps keep the body healthier and the mind cleaner. On lighting a lamp In almost every traditional Indian home a lamp is supposed to be lit daily before the God. All auspicious functions commence with the lighting of the lamp, which is often maintained right through the occasion.
Light symbolizes knowledge, and darkness, ignorance.
Hence light is worshiped as the Lord himself.lighting the traditional earthen diya has its own meaning. The oil or ghee in the lamp symbolizes our vaasanas or negative tendencies and the wick, the ego. When lit by spiritual knowledge, the vaasanas get slowly exhausted and the ego too finally perishes. The flame of a lamp always burns upwards. Similarly we should acquire such knowledge as to take us towards higher ideals.