Muscle loss with low bf%?

Hi,

I’ve done several dry fasts before, and I love the feeling and the health benefits of it. I really want to do some more fasting, but I’m holding back in fear of losing lean mass - (I’m leaner now than I’ve been before when doing regular fasting.)
I lift weights several days a week and have a fair amount of muscle mass. Female, 41yrs, 66,7 kg(147lb), 170cm(5’7) and ~18% BF.
Does anyone have good data from dexa scans (after refeed) or similar, from before and after dry fasts to show? How many days are “safe” to do when I want to preserve muscle? TIA