This need to not see that she's always thought that she was ten pounds, no more, no less over a target weight no matter how much she currently weighs helps, as I said before, to explain another seemingly inexplicable phenomenon: the fact that she's convinced that this habit of hers of looking in the mirror and seeing someone who suddenly ballooned up and lost her self-confidence is always a new thing. Always and ever, she wails to her friends and family that before now, she was a happy woman who never obsessed about her looks or her weight but now that she's gained ten extra pounds, she can't stop obsessing about something that never used to bother her. At some point, the family must have realized that they weren't going to get anywhere trying to remind her of all the times in the past that she's declared that she's a blimp.
While this is because they don't want to get into a row, they don't understand why they're avoiding said argument. Elly would rather not admit that she's always thought that she was ten pounds, no more, no less over her target weight no matter what because she'd then have to bear the public stigma of having a psychological disorder. Well, that and confront the even more terrifying possibility that no one cares especially as long as she's happy.