There are junk food vegans just as there are (in much greater quantities) junk food meat-eaters.
I'm a little overweight- not clinically overweight, but I have some extra lbs on me. I have a hard time saying I'm vegan because of this too, but I'm also getting more into raw, stand for health and whole foods, and am active. So, yeah, I'm vegan, but I also drink green juice as meals, eat tons of salads and fruits, and work out most days of the week. Plus, I have an acne problem.
All of that makes me uncomfortable telling people. Here I am, so health-conscious, but it just doesn't reflect in my body.
But things are changing for me. I am the way I am right now from binging after losing weight way too quickly and obsessively. The more raw I eat, the better my acne gets, and I've lost 4 lbs so far- though it's been a struggle... but I'm getting there.
I live in the States, so being fat is much more accepted in our society, so it may not be much to you to say that whenever I DO tell others I'm vegan, I always get a response along the lines of, "Oh, I could never do that" or "I could never give up meat/cheese". Nobody gives me a puzzled look...