For me as a vegetarian it came down to an equation. When I was younger I enjoyed eating meat, but then I started to think about the suffering of the animal. Take a hamburger or steak you eat for instance. That came from a cow who spent his entire life in a feed lot, an enclosed, filthy, dirt field where literally millions of cows stand shoulder to shoulder, unable to move. They are pumped with drugs so they don't get sick and die. It's a terrible life. I started wondering if those 5 or 10 minutes of enjoyment I get eating a hamburger were worth that cow spending his entire life in such horrible conditions. The answer for me was no. The intense suffering of all those animals was something I did not want to be a part of.
So it's not so much about eating meat as it is about the condition the animals you eat are living in. If everyone hunted their own meat and ate it, I would actually have no problem with that because that means the animal got to live it's normal life until an organism higher up the food chain killed it and ate it. That's life, that's how nature works and I have no problem with that. But these feedlots and chicken/pig farms with millions of animals are nowhere near natural.
So actually, if the only meat you eat comes from hunted animals, I consider you to be very similar to a vegetarian from an ethical standpoint, as odd as that may sound.
Of course, humans have to ability to step outside of the natural food chain and that ability skews the ethics a little bit, but that opens up a whole new philosophical debate. So I'll just stick with what I typed above
