Sforno on Leviticus 22:7/ספורנו על ויקרא כ״ב:ז׳

1כי לחמו הוא, and he need not await his atonement before he may eat what is his regular diet, לחמו. Our sages in Pessachim 35 stated that as soon as the sun has set the priest (who had ritually immersed himself after having contracted ritual impurity) may eat t‘rumah. [he may not yet eat sacrificial meats which are of a higher level of holiness until the following morning as those are not considered his לחמו, regular diet. Ed.]