As somebody who grew up in Michigan not far from Battle Creek, I've always been interested the history of wacky self-improvement regimes. (You may remember "The Road to Wellville" as one look at that. [1]) E.g., the inventor of Graham flour believed in all sorts of self-harshness: "Graham created a theology and diet aimed at keeping individuals, families, and society pure and healthy - drinking pure water and eating a vegetarian diet anchored by bread made at home from flour coarsely ground at home so that it remained wholesome and natural, containing no added spices or other 'stimulants' and a rigorous lifestyle that included sleeping on hard beds and avoiding warm baths." [2]
I know these things are cyclical, so I expected it to come again. And as a someone who's currently trying eTRF [3] I think there's real value in self-experimentation. But it's really weird to see a full-blown health fad complex turn up in the tech industry where we see ourselves as so very rational.
[1] https://en.wikipedia.org/wiki/The_Road_to_Wellville