How about considering different viewpoints? Main stream advice should always be questioned. Also, different diets work for different types of people, and there are 10000 other factors. You can't simply isolate one variable, complex systems don't care about your linear ideas.
A an upcoming documentary an alternative theories related to this: http://perceivethinkact.com/
Also checkout the forums yourself, and then decide if these people are unreasonable:
https://raypeatforum.com
That is assuming you are not suffering from a bias towards authoritarian sources. ;)