She gained some weight but she is not fat at all!
He said in his post she has put on weight. Why lie when there are many other not lying answers that are much better?
She was underweight before because she hardly ate anything. She’s way better now. But some people comment on her change of weight because they compare it to how she was before.
When she was under weight, just tell her she looks a lot healtier then she did and most importantly that you like her no matter what.
With humans it’s just like with other animals, you shouldn’t be able to see the ribs, you need to be able to feel them, just. (You can go hunt for them and tickle her to prove it ;) )
It´s a trap. She seems to suffer from an eating disorder, so if you directly respond to the statement, you can only lose. No matter what you say she will find a way to turn it around. Instead ignore the “I am fat” part and immediately steer away from the topic. Try something like:
I’m sorry, it looks like this is freaking you out. You know it’s not useful to talk about it, right? So, let’s do something to change the mood. Shall we (insert activity you both enjoy) instead?
I wish you both all the best!
‘Tell your gf to just ignore it and not talk about being upset to you’ is a great way to ruin a relationship. A woman being upset is not a trap, and viewing relationships as adversarial is setting yourself up for failure.
ETA: This guy can’t stop editing comments to try to make it look like he had less of a meltdown than he did.
Has gained weight is different than is fat.
She could have gone from 97lbs to 98lbs. Gained weight, but not fat.
It’s not lying. Fat and overweight mean different things in this context. Fat is a pejorative word, carrying a negative connotation. Overweight is a statement of fact
The gf isn’t saying, “I’m fat,” as an acknowledgement of her weight being over the recommended bmi, she’s actually saying, “I’ve gained weight, and I feel ugly and I’m concerned you won’t be attracted to me anymore.”