It certainly is interesting.
Apart from the extremely poor, people seemed to eat far more healthily; lots of veg.
Mr Kellogg certainly had bizarre ideas but some people from London may remember a character who preached the doctrine, 'meat causes passion'. He walked the streets of central London with a sandwich board and handed out (probably sold, I don't remember), leaflets which he printed himself. He was around for many years, one of London's well known characters. I saw him lots of times and recall an article about him, with photograph, in a Sunday supplement.
Here he is!
https://en.wikipedia.org/wiki/Stanley_GreenSorry if I am sidetracking but the article you have linked to brought him to mind.