Why some people eat a lot of meat?

My brother, 13, is a true carnivore and eats a lot of meat. He doesn't eat any other food so much. I have seen him eat 3 tandoori (full) chicken, almost 2 kgs of pot roast and much more in one sitting. His appetite for vegetarian and other food is normal but he never seem to have enough of meat. He doen't eat a lot but eats a lot of meat. Is this a problem?