No one on here can help other than guessing, she needs to speak to her doctor
>She wants to lose weight, she tried all diets, but nothing helped.
Thats not correct thoughEating less calories than your body uses makes you lose weight, thyroid issues or not.Thyroid issues just mean the calories out are typically lower than you actually think.
Also can she use medication like T3 to if not fix it at least compensate for the issues.Thats a question to her doctor
I would recommend Dr Stephen Cabral’s podcast, you can go on his site & search his podcasts by keywords. He has a lot of useful information in regards to thyroid, hormones, & also fasting. Hopefully that will provide some insight on how best to proceed for your friend. Good luck!