Yes, I’m on my 6th 72 hour fast since the end of August, and now it just feels like routine. I know there will be a ghrelin spike, I’ll be hungry tomorrow and frustrated, and I know those feelings will disappear by tomorrow night after which I can just cruise. Understanding these feelings and their causes makes it much easier.
I’m not sure there is any evidence that your body increases expression of enzymes due to past fasts.