The fact that your current cup size isn’t too large (you might not even have so much fat to lose there) and that you will be fasting over a long period of time (which helps reduce extra skin/sagging) means that this might not end up being a problem for you.
I’ve lost 80lbs so far and there was a brief moment where I wondered if I would start to have a problem, but in the past few months the girls have been perkier than ever. This could also be due to my frequent hot yoga practice, so if you’re concerned definitely pick up some exercises that you enjoy because that could go a long way towards preventing the problem.
Personally, I wouldn’t mess with your estrogen because extended fasting already leads to periods of time when your body pumps up estrogen production far beyond normal levels.
I’m not sure why, and it might sound silly, but I’ve always been under the belief that autophagy would sort things out aslong as I wear a firm fitting bra. Saying it out loud makes me realize that just doesn’t sound feasible.