Female friends always pursue perfection. I would rather endure the thirst for beauty than be a' paper man'! This is entirely because of psychological effects! If you find that she is not very keen on losing weight, you should persuade her! In order to prevent her from affecting her normal health because of a temporary idea. I believe your words still carry a lot of weight!
The rest is up to you.
Well, that's all my advice. I hope I can help you! I wish you happiness!