Remember that fasting helps preserve muscle during weight loss
this isn't true
eta: to be productive, the three controllable things that actually make a difference for this, in order of importance:
1. doing some amount of resistance training
2. not losing weight too fast
3. eating a reasonable amount of protein
everything else is like on the margins stuff that maybe matters if you're getting super lean (by your body's standards) and trying to step onto a bodybuilding stage at the end