I can tell you one thing – it will be a little weird on your stomach. I've gone months (not quite years though) where I had a vegetarian diet, and when going back to meat, it didn't "sit right" in my stomach at first.

So my advice from personal experience is to ease into it and things should be fine. Everyone has a time in their life where they start eating something new, and this isn't any different, so I don't see any dramatic problems arising.