Explanations of such things often get to be a fine line because people seem always to then want to go to rediculous lengths. If you answer a long time then people say oh my, when I go to the bathroom then that would be bad because I don’t want to flush God into the sewer. If the answer is short it’s another problem.
Anyway, theologically, the answer is really forever. In that effectively you become the element. Why are we all one body, it’s because of the one bread, well just bread can’t do such a thing. So it’s the presence of Jesus that unites us into one body, his body, the church. You aren’t just a member of the church for a few moments and then you aren’t again until you partake again. And the blood, well lot’s and lot’s of the bible is dedicated to teaching you that the life is in the blood. When you receive the blood of Christ you receive his life. Really eternal life. Again wine cannot do such things, it is because it is Christ. And that life isn’t just there for a moment and then gone again, it remains forever.
The bread, the wine, they are gone eventually, some incorporated into one’s body but basically gone just like any other bread and wine. But Christ is not then fundamentally gone because the bread and wine are gone. Christ remains in you. If he doesn’t you are in big trouble.
JJ