What is meant by Fasting time (Upavasa Kaalam) ?

The meaning for the Upavasam, is not to take any food and also even not to swallo the spittle.

The Upavasam  is for remembering the God constantly and spend the time in the yearning

of Him only.  The Mind does not have the power of seizing the Athma Swaroopa (Self Knowing ) immediately because of its nature to spread widely to accquaire the worldly things (Prapancha vishayasakti). In general the Mind has the power of grasping things. But due to the previous Samskaras and also by the nature it runs after the world, which is Illusion (unreality).

So in this contest, observing the Fast, not for taking food, but  it is only for meditating 

constantly the Self. 

By observing the Fast ( fasting) so many bad elements  (foulness) will be removed

in the body. The fasting means by worshipping the God besides the body also. So, 

the Mind and the Body are to be worshipped in this way.

In the olden days the people used to observe fasting so strictly to come out of their sins.

In the Mythologies it was said, one should have to do the fasting in the auspicious days

to get rid of their sins if they did by mistake.

The fastings are observed when the friends and relatives do not visit our house.