A few people (including E and Echo) have pointed out something only tangentially related, but quite troubling, and of interest to many of us.
What I see from their comments is a reminder that society as a whole sees certain types of bodies as transparent reflections of the person, and as worthy of moral judgment.
If you're heavy, people assume you must be: unhealthy, lacking in self-control, disgusting, sloppy, etc. etc. If you're quite curvy (independent of size although these things interact), you must be: slutty, sexual, indecent, asking for it, etc. I'm sure there are other stereotypes of other body types, but these are the two that have come up.
Obviously, this is ridiculous. You can't know anything about someone's health, lifestyle, or morality based on what they're shaped like - you can only know what they're shaped like. (I'm not going to veer off into race, disability, other kinds of concerns ... but it's worth noting that there are a lot of similar issues there.)
One thing that's especially insidious is that if you're of a shape/size that means that people wrongly feel entitled to make moral judgments about you, there's a tremendous amount of pressure to dress to counteract those "automatic" judgments. (You may see, again, why I find myself drawing parallels with other topics.)
I always worry that to some extent, doing so only reinforces the stereotype. If we dress to avoid the stereotypes that "All [heavy, curvy, etc.] women are X" are we convincing people that it's not true, or are we only convincing them that "[Particular woman] is special and thus not X"?
(At the end of the day, I do keep in mind the issues about curves when I dress, because I've experienced that kind of judgment - but I don't like that I do!)
Forgive the ramble - I'm very interested in how people of different sizes and shapes are perceived, and I'm curious what others think.