As I'm sure everyone will suggest, she should see a therapist. You can't magically make this view of herself disappear, but you can help by continuing to compliment her and lift her up with your words and gestures every chance you get. Be very specific with compliments, be sweet, be naughty...all of it. When other people say nice things about her or when you catch another dude checking her out, tell her! Be affectionate, and generous with hugs, back rubs, etc...human touch is very powerful, and you're the only guy in the world right now who gets to do those things for her. Isnt that awesome? Ask her opinion on things, any subject, just try to get her talking and then just LISTEN. Show her you care about what she says, that you think she is (intelligent/witty/empathetic etc) and that her thoughts and words matter. Write her a letter explaining why she is the most stunning human being ever, inside and out. Do not discouraged if you don't notice an improvement in her self esteem..you are making a difference, no matter how slow or small...just be patient. Everyone should be active and exercise, since she is very sensitive right now you should come up with an activity that isn't like HEY LETS GO WORK OUT, but rather something that bonds the two of you and gets you moving at the same time. Sign up for salsa or ballroom dancing, tennis lessons, go on long hikes and have a healthy picnic, that sort of thing. Yeesh, sorry this is so long- I have struggled with body dysmorphic disorder my whole life...I do still have bad days/weeks but thanks to my loving, patient husband that negative view of myself is no longer my constant reality. I wish you and your girlfriend the best, it may take a while but change is possible! Sending positive vibes your way!