“Fit for Life” is a fad diet book based on “Natural Hygiene” and on the legendary woomeister Herbert Shelton’s reality-oblivious theories of food combining – if one eats the food in the wrong order they “cause fermentation” in the stomach, and “dead foods clog” the body, whereas “living foods cleanse” it. The ideas have been refuted by research, but this seems not to matter for Harvey and Marilyn Diamond, who have sold millions of books promoting the bullshit. Harvey Diamond has his degree in nutrition from a diploma mill, and it shows – most of the book is firmly based on the ecological fallacy, including the ridiculously false and misleading but exasperatingly common idea that “animals in nature are magnificently healthy in comparison to the health that we humans experience” whereas pets and zoo animals develop “many of the problems of humans” (there are alternative and better explanations for why it is rare to see debilitating diseases in the wild than invoking natural as some sort of white magic). The main claims of the Diamonds are covered here, though see also this admirably comprehensive list of dubious health practitioners.
Diagnosis: There are quite enough of these loons around, and exposing them will probably help little or nothing. Still, we have a duty to try, and the Diamonds constitute yet another scheme to exploit human biases and anecdotal evidence for purposes that have little to do with truth or well-being, regardless of what the Diamonds themselves may believe.