The problem is sugar and refined carbs. Nothing wrong with meat and fruit, veg, nuts. Vegans must supplement. If I were to give up anything it would be plants, not meat. All meat diet requires no supplements. Vegan diet requires supplements to prevent early mortality.
I'm not recommending it. Just countering the bad advice given above my post to give up meat. What I said was simply that if I had to give up one or the other, it would be plants. A vegan diet does not provide all the nutrition necessary to keep a human being alive without supplements. A carnivorous diet does. If you are going to give up a food, why give up the one food that will sustain life without an supplements. Think of it this way: The purpose of eating is to take in the nutriments that will build, repair, and sustain human (animal) tissue. What makes you think that broccoli is better suited for this than a ribeye? The real poison is sugar. The next is refined grains and cereals. I have no beef with plants. But I'd rather eat no plants than no beef.