I started having health problems after I moved back to the US (years ago, have since left permanently). So I started researching and found that a lot of what they teach works. I found a photo that summarizes it quite well:

The only reason I bring this organization up is that it was the first "big step" on my journey towards health. A lot of what they say works. They especially teach against eating western-produced bread. I noticed that when I eat bread produced/farmed in a western country, I start to have pain in my teeth and bleeding/weak gums. Whereas bread produced/farmed in some 2nd and most 3rd world countries was fine; it had no such effect on me.
Weston Price was a canadian dentist who worked in the US. He traveled the world and visited its most "primitive" people and researched their diet, from the Inuit of Canada to the natives of Papua New Guinea (and many, many more). He noticed, without exception, that the more "primitive" their diet was, the healthier, stronger, and more good-looking the people were. Whereas when they adopted a traditional western diet (processed food, mass-produced bread, genetically modified vegetables and starches, hormone treated meats, etc), the people's health declined immediately, cavities began to appear (whereas they had none before, despite never seeing a dentist in their life); the next generation (after beginning a western diet) was shorter, their jaws were smaller (so they "needed braces") and they had a lot of psychological problems. Some of the natives even ended up taking their own lives after beginning a Western diet, because the pain was so bad from the cavities they developed. (They had no access to a dentist, obviously.) He also mentioned that a person's "soul" seemed to develop to a greater extent with proper ("primitive") nutrition, by this he meant that they were kinder, more caring, more good-natured, and more deep-thinking than their peers (often their blood-relatives) who ate "the white man's food". If you haven't understood what I'm talking about, think of it as the difference between the average American white male (asshole), and the average villager you meet in a 3rd world country. Huge difference, and it is hard to grasp it unless you have met people like them.
Weston Price has a book, "Nutrition and Physical Degeneration", you could buy it if you're feeling generous, or just google the name of the author, book, and "PDF" and you should be able to download the whole book for free (you can, I checked). Use a VPN (free ones are available). It's a huge book, but you can skim for the details you need. His journey is impressive.
I never recommend that anyone dedicate themselves to a diet without knowing what works first. But that's the point of all these organizations, you get ideas from people that claim to be dietary saviors, you try them, and whatever works for you you use throughout your life to maintain health.
Of course, the "medical establishment" in the US has "discredited" him, which means everyone who actually wants good health should pay notice to what he is saying..
http://www.westonaprice.org/health-topi ... uidelines/