I was thinking about macrobiotics.
That's an interesting area. The late Abe Seiseki said that Morihei ate macrobiotically when he came to visit him, but not at other times.
The common link between those two is Kenzo Futaki, a disciple of the late-19th/early 20th C. neo-Shinto revivalist Bonji Katsuwara. Futaki espoused both Katsuwara's (divinely inspired) misogo-no-gyo and the brown rice-based diet later made famous by George Ohsawa as macrobiotics. Futaki's source for the brown rice diet isn't so clear to me.
All that said, the impression I always had was that while a number of people who were deeply devoted to macrobiotics had associations with Morihei (and vice versa), and while he followed a "when in Rome....: practice with regard to his diet, he wasn't himself a rigorous macrobiotic eater.
But perhaps my information is incomplete....