What's the best thing to say to a girl who THINKS she is fat?

[Zhukov]

My girlfriend imagines that she is overweight, and that I find her unnatractive.

She's gorgeous, and not large at all. She's not just fishing for compliments, either, she actually thinks she's fat. I spend all the time I possibly can telling her how beautiful she is, and touching her, I definitely AM attracted to her.

I'm wondering what other people would say. I reinforce how desirable I find her, and usually wind up using reason and logic. Doesn't really work.

Damn fashion industry.