Some interesting happenings here. For one, Moses, Aaron, and the two sons were all assigned to tell the children of Israel what food was clean and what was not. Rashi says they were all asked to do this because they had been silent when Nadab and Abihu died. They “accepted the Omnipresent's decree with love.”
For another, this seems to be about what is clean and what is not clean. All my life I thought clean/not clean had to do with health. Last week a rabbi said that was not a consideration back then. Rather, it has to do with what draws people to G_d, and what takes them away.
And I think, as all the rituals did, it has to do with being very intentional about what one eats and what one leaves. And the leaving seems like it has to do with leaving some for G_d. It is preaching against gluttony. Don't just stuff yourself. Look at what you are doing!