Why should one Fast on Eakadasi etc; What is the importance of same?

Fasting on any specific day is to clean and refresh the body mechanism. This helps to keep one healthy for a long time as frequent fastings allow the body system for overhauling. Please read the article on Eakadasi fastings Page in the Srivaishnavam practices for a full coverage. (www.trsiyengar.com/id18.shtml ) and also the a story from Narada Purana.