Good for you. I am guessing that your family is fairly big, also? Most of my family are very tall. I am 6'8" and some change and run around 210 during running season and about 220 during the off-season. Do I attribute that to my diet? No. I attribute it to the fact that my family members before me were/are very tall. Average height for the ladies runs around 6'2" or so, and average for the guys is around 6'5" or so.
I think that it is funny that you keep insinuating that meat-eaters tend to be fat (yes, you do insert the word "usually", but still). I actually don't know many vegetarians, and no vegans. Of the few vegetarians that I do know, over half of them I would consider to be a bit "chubby". Eating right is part of it. Another big part, IMO, is exercise. Even if you are only consuming veggies, but still wolf down massive amounts of calories and don't do anything but sit on the couch and watch TV, you are probably going to gain some weight.
Taste.
Everything aside, I truly do love vegetarians and vegans. Means more meat for me. :rockin: