People don't live like their instinct says anymore. If you see a rabbit, do you start running after it to catch it and eat it raw? I don't think so. Working on an office isn't following our instinct either. A lion has instincts, you can't stop him and I don't want to, lions are nature. When I use the internet, ride my bike to school, use a pen to write, it isn't nature, I'm not following any instinct. Actually only things you like are things your instinct tells you, when you follow your instinct, it gives you satisfaction. I get just as much satisfaction from eating a burger as I get from eating a vegan burger. Actually I get even more satisfaction from eating a vegan burger, because I know I'm saving someone, by not eating meat. Because our instinct also tells us to help others. So if we have to follow our instinct like you say, we have to go veg. Why would vegan be unhealthy? You can still get all your nutrients.