To my fasting girls

Hello, i’m 21F and before i did extended fasts every month (between 72-92 hours) to improve my insulin resistance and to lose weight. After my 4th extended fast i lost my period for like 2-3 months. Now I have return back to normal and i would like to start fasting again but i don’t want to fucked up my body like before. Do you have any tips for this? When it’s the best time to start a fast to sync with your period?