From the McGovern Report:
“The question to be asked, therefore, is not why should we change our diet, but why not? What are the risks associated with eating less meat, less fat, less saturated fat, less cholesterol, less sugar, less salt, and more fruits, vegetables, unsaturated fat, and cereal products—especially whole grain cereals? There are none that can be identified and important benefits can be expected.”
So the question, contrary to @RobC (sorry Rob) is not as much a fallacy. We have done untested trials before. This trial is the McGovern report put into action and continually refined rather than reviewed. That it is refined speaks to the fact that everyone seems to have overlooked the commission itself wasn’t willing to wait any longer and had a strong desire to act.
Those actions have been seriously detrimental. Under those guidelines we as a country and world have become more obese, more T2D, more Alzheimer’s, more depression, more more more.
So Rob C other point then should be considered: What diet can I follow that is not dangerous, long term. Here, you are alone. You must decide for yourself!! I accept that the evidence for the LFHCMP diet is flimsy at best. I also agree that the evidence I see from long term -10 plus years ketogenic living in a steady supply of N=1 anecdotes is enough to compromise a minimum epidemiological study that actually works pretty good at removing answer bias. Under this I am willing to move ahead as I DO KNOW that short term benefits are astounding- far better than any other eating plan other than the possibility of carnivore.
That is my take anyway.