I could swear I saw a study like this in humans decades ago. It would have been in the 80s when I read about it. It had similar results. Basically a slower metabolism leads to a lot of benefits. The only thing I could find that references historical studies is here, and it's a good read: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014770/

There's not really a way to test it in humans, to be fair. You can't take old people and say they'll live in your clinic for the rest of your life and will eat only what they give you