The Natural Hygiene lifestyle & protocol was formulated by the late Dr Herbert M Shelton , who singlehandedly collated all of the health/disease information from the written works of the pioneers who preceded him, and who were mostly medical Doctors of their era.
These medical Doctors abandoned the drugging practice of "therapeutics" which was seen as worthless, and relied solely on Nature as THE authority on achieving wellness and freedom from disease: their success in the eradication of disease in their patients was unequaled, most notably during the American Civil War, where many more lives were saved thru the Hygienic care of wounded/diseased soldiers, than by the conventional medical paradigm at that time.
Shelton wrote prolifically of their and his own experiences during his lifetime, but we also owe a great debt to the "The American Natural Hygiene Society" for their staunch defense of health rights in the political arena, as well as for organizing an impressive array of books on the natural laws of health thru Natural Hygiene.
However, the popularization of Natural Hygiene came about in the mid 1980's by Harvey & Marilyn Diamond's best-selling books, FIT FOR LIFE I & II--- which sold over 11 million copies worldwide! I would strongly urge you to purchase these two books which explains the NH protocol better than anything else I have ever come across.
You will also find via google that there is much misinformation and "debunking" of the Diamonds books by so-called "experts" such as the American Dietetic Association, who claimed that the NH lifestyle was "injurious" to health, for the only reason that they disagreed with it: despite the thousands of testimonials by people who had followed this protocol from their books with much success.