Epigenetic clocks are really hit-and-miss and are mostly used at population levels and not a good way to measure changes in a single human. They may be accurate

Epigenetic clocks are really hit-and-miss and are mostly used at population levels and not a good way to measure changes in a single human. They may be accurate +/- 5 years, which he even says in his footnotes. Which is not to say he didn't get a lot healthier, but the focus on biological age/epigenetic clocks seems to be more of a marketing instrument than anything else.