God bless, Fathers. I have a question; how do we offer the Eucharist to God if we're the ones eating it?

Like, specifically the act of eating our Lord's body, blood, soul, and divinity in the Eucharist.

How is it an offering to God if we're the ones eating it? It's like if I made someone a sandwich, said it's for them, then proceeded to eat it myself.

Just wanting some clarification, I do acknowledge that it is an offering. Just want to know the hows :)