I'm not trying to avoid the subject, I just put in my two cents. I would not accuse someone of having an eating disorder without facts. If you look at her size now compared to the first season or so of edgemont, it really isn't that much different. She plumped up for a few seasons of Smallville, and then lost dramatically when she did Partition. The first time I ever noticed it was in S5, especially so when it seemed like wardrobe was trying to bulk her up with extra layers of jackets and shirts. Here is a picture from comparison of her wearing the same shirt in S3 and S6:
It is apparent that in S3 the shirt fit just right, snug tight on her frame, whereas in S6 it seems to have been pinned back, which is clear by the way there is extra loose fabric under her arm. It's obvious that it doesn't fit her the same way, but it's not that much of a difference, and in S3 KK was a little more filled out (but by no means chunky or fat) than in others. I would say she's lost 15, maybe 20 pounds tops.