Shedding and going on/off feed

I have noticed that the snakes that I had go off feed usually seem to do so just after a shed. Not saying every shed of course, but just before they go off feed, they always seem to shed once first. For example, they would eat fine, shed, eat again, shed eat again etc. Then suddenly one shed, then refuse food for weeks or even months.

I have also noticed that many (not all) that may have refused food for a long time, that even when they start eating again and eat a TINY meal, they will all of a sudden shed. I have two snakes that are 1000+ grams that went off feed for a couple months, I got them back to eating by offering a F/T Mouse instead of rat, and those big snakes that haven't eaten for months, eat a tiny little mouse maybe 30 grams and they shed suddenly.

Why is this? Any one got any ideas?