I do feel there is something very substantial regarding the various human metabolic states as they relate to these seemingly "everywhere" diseases that have no definitive causes.
Ketogenesis is arguably the most ideal state for our bodies to operate in, but it is also arguably the hardest one to maintain in our society. It is difficult for most to consistently ignore that big-ass box of krispy kreme donuts your asshole coworker brings in every day. Just one of those per day is probably enough to keep you stuck in glycogenesis for the rest of the morning and into part of the afternoon.
If you look at the push of HFCS and other crappy food options with incidence rates of cancer over the last 3 decades, I am pretty sure you will see some correlation there. Obviously, it is hard to draw a causal link between these, but at a certain point I am going to give up on the academic explanation in favor of a series of practical observations and whatever inferences I can draw from those. I am also acutely aware of the influence of profit seeking in the medical & academic communities. When I see a study come out that says something along the lines of "sugar isn't actually that bad for you" I immediately think big sugar or corn financed this research piece for their own benefit.
I have personally fasted for stretches as long as 5 days, been on one-meal-a-day, and have been on ketogenic diets for months at a time. I have also been a complete waste of a human, eating and binging on all manner of sugary, carb-loaded foods and other unspeakable horrors. I can tell you that 100% of the time, I felt better in the ketogenic state. Sure, you can argue for that very brief feel-good you get from slamming that donut, or the mental fortitude required to force yourself into keto. But, at the end of the day, once you are keto it's easy. It's just the transition phase that sucks. As with most things.