Are all sentences OK?
I eat it three meals a day.
I eat three meals a day.from it.
I've been eating three meals a day from it.

Question

Answer

The first sentence is fine.
I eat three meals a day of it OR I eat three meals of it a day.
I've been eating three meals a day of it OR I've been eating three meals of it a day.

Answer

1.  This is fine. It tells us that you have breakfast, lunch and dinner every day.

2 and 3.  These are strange. We have no idea what 'from it' means.