i used to be vegetarian when i was in middle school simply because i didn't like the taste of meat that much, and i don't support the inhumane meat industry. i ended up having to stop though, because my mom wasn't willing to buy me separate groceries. now though, i buy my own groceries and decided to give it another try. the same reasons still apply really; i just don't like the taste of most meats and morally i can't support the meat industry. having an easy out for fast food, junk, etc. and losing weight is just a great side effect, i suppose. it also makes it harder to binge since there's less for me to actually be able to binge on.
soooo tl;dr: it's not the main reason i started, and if i didn't have an ED i'd probably still be vegetarian. but the ED benefits are a good plus and a reason to keep going with it