I was nearly a vegetarian before my pregnancy -I ate meat rarely and only in small portions. Then I suddenly hated most vegetables! I was never sick, I just could not make myself eat them. Also, I've completely lost my appetite. Even if I feel starving, I can eat about half a plate of food before I feel Thanksgiving-style-full. I'm 18 weeks now and have felt full like that for months! It's weird.
I finally gave up on eating healthy and just started eating whatever I wanted once I realized I was pretty consistently losing weight. All I want are hamburgers, boxed mac'n'cheese, and canned tomato soup. A couple of weeks ago, I finally got over my veggie aversion so at least I can eat those on the side!