I don't think it's that she's fat (she isn't) it's more of a perception. She never seems to stop eating, she has noticably put weight on, some of her clothes are tighter making her hips hang over giving the impression she's fatter than she is and she does wobble about more which some people equate to being fat.
Add to that the terrible hair and the general slobbiness, it's not overall the look some people associate with a glamour model
I think she looks fine other than the hair and knockers.