I disagree with you

It is not "ridiculous" if she has a serious problem with self image which might be already interfering with her present or future idea of a sex life.
I'm no enthusiastic advocate of cosmetic surgeries per se, and I do believe that there is a frenzy of dangerous and unnecessary surgeries being done these days, but I do recognize that reconstructive surgeries when performed by certified, reputable surgeons, can have a very positive result in the life of whomever may be in need of them.
As far as I can tell, the labia is not a part of the sexual organ that would interfere with sensations, such as a clitorectomy and/or infibulation (yikes!!!). With a good surgeon, there is no reason to assume a damaged sex life. If indeed the skin in question is hanging out in disproportion, then there are no diets or excersices that would help, only going under the doctor's knife can resolve this. This is not a choice I would want to pick for myself, but I'm not her, and ultimately this is one of the most intimate decisions anyone can make, and it is thus solely hers to make. I wish her much happiness regardless of what she does.