Girls, how do I reassure my girlfriend that she's not fat?

[therealadamreed44]

My girlfriend is always worried about her figure and I have to keep on telling her that she has nothing to worry about but she doesn't listen to me.

My girlfriend is 5ft 8" and weighs around 120lbs. But she thinks that her being this size means that she's overweight. She also hates the size of her boobs, she's a 34D.

She also thinks that because she has to wear clothes in a size Large that also means that she is fat.

Obviously she isn't fat or overweight and I keep trying to tell her this but she never listens to me.

Whenever we go out she's always looking at the petite girls and girls in tight clothing and says that she wishes she looked like them. But she has a figure where she can wear tight clothing without looking ridiculous too and I've told her this but it goes in one ear and out the other.

Girls, how do I reassure her that she's already beautiful and that she's not fat or overweight?

[quaranta]

At this point I wonder if she is doing that on purpose with you as an easy technique to get praise and attention, through victimism.
In any case if she wishes to be extremely skinny, the only way is to eat less and move more. So if she is really determined to become skinny, and not just staying like that in order to have an excuse to complain, then try supporting her in getting skinny, changing your approach to see what happens: tell her you like her a lot the way she is, again, but that you also want to support her choices, so ask her what is her plan to become skinny anyway and if she wishes to share something of that with you (working out etc), that you're up for that. You might joke by saying you'll need to have more sex, or to invert roles more about who is more active in bed.
See how she reacts. If she is weirded out by the fact you're taking her wish to become skinny seriously and you're respecting it, then all she wanted to do is to keep a reason to complain about her body to get attention. If that's the case, next time she does, you can remind her she either let you like her body shape for real, or decides to become skinny. Not complaining continuously without a solution.
Instead if the problem is really that she feels really fat and thinks you're lying to her just to be nice, maybe you can start praising her looks in other ways: show her how horny her current curves make you, boobs and butt, and how you enjoy them, then when she complains about her weight tell her you would miss the best parts of her body and some satisfying sexual practices like eating her boobs with taste if she was skinny. Maybe tell also something generic about men who generally prefer way more curves and a skinny look (skinny look is promoted by models and girls themselves, but that don't constitute the real preferences most men have).

[Guy13]

you can not so STOP trying as you will make it worse...