Been on many fasts over the last 40 years or so. The longest being 30 days. Never felt like there was a recovery time. In fact I was always working.
Many of them I exercised the whole time not knowing any better. There is theory that rest is better to get the maximum from your fast, and it makes sense to me.
Your body will tell you if you need to end the fast early. [Provided you are paying attention] I stopped a fast once when I felt a pain in the liver/gall bladder area that felt like I was trying to pass a stone. Whatever it was it was over in a day or so.