Q. In Genesis 9:3, God says, "Every moving thing that lives shall be food for you. And I have given you all things, even as the green herbs." However, in Deuteronomy, it restricts food to "Things that split of the hoof, and chew of the cud." It's confusing.This is a really good question, because it appears as if God is saying one thing in one place, and then later changes His mind. So this is where being a good Bible student comes into play. We must look at the entire evidence from the Word of God and not simply take one verse to establish doctrine.
God does say that there are clean foods we can eat and unclean foods that we should avoid. In Isaiah 66:16, the Bible says, "They that sanctify themselves and purify themselves in the garden, behind the tree in the midst. Eating swine's flesh and the abomination and the mouse, Shall be consumed together, saith the Lord." In other words, those who eat those things that God clearly condemns are an abomination.
In Genesis 9:3, we have to take into account what it also says in Leviticus and Deuteronomy. That's the complete statement from God, and you can bet that Noah knew this because he took clean and unclean animals into the Ark with him.
However, if you keep reading in Genesis 9:3, the very next word after "green herbs" is "but." So God is saying, "But I've got something else to tell you about what you ought to eat." From there, He says we shall not eat flesh with its life, that is, its blood. So on one hand, He's saying, I'm giving you everything. But on the other He's saying, but there are some things that I know you're not supposed to eat, and so I'm going to tell you about those things.
It's difficult to change your diet. But if you're willing to be faithful to what God says, He will bless you immeasurably. It's well known that if you have high blood pressure, one of the very first things that the doctor says is you need to get off of pork and fat. God has always known it, and He was warning us about it. I think we should follow His advice.