For what it's worth, the last author cited here, Valter Longo has a book called the longevity diet.

I've worked through that book and done some rounds of FMD personally. Where FMD is defined as roughly 5 days of reduced calories. 400 calories from veggies, and 400 calories from healthy fats like olive oil.

After one of the rounds in particular, I felt amazing afterwords. I won't pretend to care about "longevity", but I really do think there's something to it when the author suggests that reduced calories kicks the body into a recovery cycle.