The unusable parts of the animal soul are expelled during the Shemona Esrai prayer when we say “forgive us Hashem for our sins”, and in the Tachanun prayer afterwards when we say “we have become guilty”, in order to remove the waste of the animal soul and push them away.
However, we find that there are two types of eating: 1 - weekday eating, 2 - Shabbos eating. These two types of eating are referred to in the verse (Mishlei 13:25): “A righteous man eats for the satisfaction of his soul, but the belly of the wicked will be lacking.” The Alter Rebbe will explain how the above verse references these two categories of eating:
The purpose of eating during the weekdays is in order to spiritually refine the food, removing any unholiness. This is expressed in the verse as “the belly of the wicked will be lacking,” meaning that the forces of unholiness are deprived of their sustenance when a Jew eats in a holy manner, disconnecting the food from unholiness.
We see this idea also in the Zohar that says: “With Wisdom-Chochma they will become refined,” (Zohar Vol 2. p. 254b), meaning, that the food becomes “blood, which life depends on”, and with the energy of that food he prays to Hashem, thus, the food which was originally under the control of the ‘Ministering Angels’ that gave it life from kelipas noga, becomes transformed into holiness through becoming the energy used to pray to Hashem. It therefore, because it came from kelipas noga, contains spiritual waste that needs to be refined.
However, the purpose of eating on Shabbos is “for the satisfaction of his soul”, meaning as described in the verse (Yeshaya 58:13-14): “And you should call Shabbos a delight... and then you will have enjoyment in Hashem’s revelation.” This idea is also found in the prayer said before Kiddush on Shabbos day (from the Arizal): “This is the meal of Hashem Who is called Atika Kadisha-the Holy Ancient One.”
