Fasting – rationale

It is common belief that when one undertakes fasting, the stomach is emptied and the digestive tract is cleared. However, this is not the only reason for undertaking fasting.
One part of the food we consume becomes the mind. If one takes food before he digests his earlier meal, the food just consumed mixes with the undigested food in the stomach. Thus, the effects of the undigested food on one’s mind lingers. If one has thus consumed stale/unsuitable food, there are higher chances of its ill-effects on the mind, if he continues to eat subsequent meals.
On the other hand, by fasting one full day, the stomach is emptied of any undigested food and any new food taken is unlikely to mix up with older remnants. Thus the ill-effects of such food on the mind is also avoided.