Vegetarians get a lot of stick. People like to try to make vegetarians justify their decision in a full and rational manner. It’s not really fair that this conversation comes up every time that they go out to diner.
One reason for being vegetarian is because it’s a lot less wasteful in terms of natural resources to feed, say, corn directly to people, rather than corn to cows to people. That logic seems solid to me. I wonder why people like to receive a fully logical answer to “why are you vegetarian”?
If I was a veggie, I’d have a canned response, something funny like: “It’s not that I like animals, it’s more that I really hate vegetables”. I think using humour is a good way to bounce the conversation onwards and not feel victimised.