For the most part, when I’m having minor skin issues or just some inflammation in general it helps more than anything.
I have ulcerative colitis, and although I do take medication, fasting was the thing that stopped my bleeding and got it under control more than anything. When I was obese it was easier to fast however now I’m in good shape it’s hard to do long fasts and when cutting weight I opt for adf now.
We are seeing this occuring in mice and drosophila flies and a few other model organisms, however the verdict with regards to humans are still out there.
One of the expected hypothesis for why this might be is that cellular respiration produces oxidative stress (Oxygen is a GREAT way to drive biochemistry, its just unfortunate that oxygen is also slowly killing us) and when we fast this is severely reduced. We see this occuring negatively in the opposite side, eating more than you need increases inflammation and oxidative stress which may end up taking part of the many “lifestyle diseases” we see in our society.
Edit: Keep in mind, the verdict is still out there which means its not easy to conclusively measure, and if it isnt easy to conclusively measure it the effects from it is probabilistically minor.
You might be interested in Dr. Peter Attia and his work on this. He’s big on lifespan and healthspan (living long and being healthy in old age). Here might be a good page to start with him if you’ve not found him already. He can get rather technical. I just kind of listen but take away the big picture from his work.