There's now a number of studies on effects of fasting on chemo therapy patients, and they all make the same claim of regeneration through autophagy for some types of leukocytes.
Well, if he was a mouse you still would have those same questions in the air until you do the proper blood tests, right?
Of course this is a naive, over-simplified interpretation of science findings, but it doesn't mean the science it's inspired by is bad.
One thing that I couldn't find any research on is what are the effects of repeated fasting cycles (and that's how most of people do it now). Traditional fasting is something you do few times a year, and then you have a recovery period afterwards. Can't find that research now, but I remember reading a paper saying that it takes about 2 weeks of normal food intake to get back to the initial white blood cells counts. What happens if you don't let the body recover and instead create a new calorie deficit stress seems unclear?
> I've hit a key milestone in cellular regeneration
What's key about it? In what way is it a milestone? What's the expected health impact in human patients?