Tetzaveh: Rav Hirsch: Mitzvah 100 – Concept 356
“They, who received atonement through them, to inaugurate them, to sanctify them shall eat them. An alien shall not eat for they are holy.” (Exodus 29:33) The Cohanim must eat the sacrificial meat in the Temple. (Rambam, Hilchot Ma’aseh Korbanot – The Laws of the Sacrificial Procedure)
The eating is here put in connection with the atonement to be attained, the eating itself must be regarded as the continuation and conclusion of the atonement. The eating of the meat of these sacrifices and the bread that went with it receives, in addition to its being a concrete enjoyment of their priestly position. (Rabbi Samson R. Hirsch)
I use my Break the Yom Kippur Fast as a celebration, and, therefore, the completion of, the Atonement of Yom Kippur.