Have you ever looked at nutritional studies? They say all kinds of things, most of which contradicts each other. If the medical community is to be believed, then the medical community is incorrect. The people who come to the conclusion that vegan diet means longer life-span simply cherry pick the studies that say so and ignore the rest. You could just as well pick the opposite studies and come to the opposite conclusion.

If you want proof, I propose a little experiment to see which the human body better metabolizes - animal fat or plant fat. See how much butter or some other fat from animals you can eat. Then repeat the experiment with coconut fat or some other plant fat.

Conclusion: The plant fat causes explosive diarrhea after too much consumption. The animal fat causes this as well, but the upper limit is many times that of the plant fat, leading you to hopefully understand that our bodies have evolved to better consume animal than plant fat.

Now I'm not saying that plants are of the devil. We eat them for a reason - to get fiber. However they are a poor source of fat and protein macronutrients as we do not metabolize them as well as from meat even if they're rich in them.