Arcadia said:
[...] I'm no dietitian, to be sure, [...]
That's the problem, me neither. Considering that we are surrounded with foods that, even if they're not wholly artificial, have been mutated over hundreds of years of selective breeding, we are in a position where we no longer know what the human diet really is. Dietitians or not, we're facing a puzzle.
I have tried various types of vegan diets for over two years, but none made me feel any good, especially when it comes to digestion. I've then re-introduced meat, eggs, and dairy, and felt better, but digestion was still wonky. I am currently experimenting with eating only animal products. So far, digestion is light years better than before, and my mood is very stable. So far it's the only way of eating that had a noticeable beneficial effect on my well being. The day I ate some vegetables, I could feel my tummy protesting to some degree. Isn't that interesting?
From personal experience, I'm confident that the idea of shitting once every full moon is wrong. I know Joe Rogan recently had a fat guy with some tales of woe, but I don't think it is to be generalized. It could be that a single diet is not applicable to all people, but at the same time, there is barely any serious research concerning meat only diets. All we have is epidemiological studies, and those are grossly inaccurate by default.