I'm personally skeptical of keto for anything other than a specified medical reason, such as diabetes, for whom I understand that there is some evidence of lowering blood sugar. My main gripe with it is that your brain runs almost exclusively on carbs, and it requires a lot (like 120-150g depending on the person). A rule of thumb is that the average adult's brain is 2% of their mass and uses 25% of their daily calories. This is mainly due to how energy intensive it is to keep building up severe ion gradients across all the neuronal membranes, and some other cells too. An ion gradient is potential energy, so it requires work to maintain the potential. The idea behind keto, if I'm not mistaken, is that it forces fat out of storage, because the backbone of a triglyceride is half a sugar molecule, so if you put two of them together you get a whole sugar, which then can be used as brain food. But then what happens to the 3 fatty chains that are cast off the triglyceride? I guess they're floating around your liver and blood until they're metabolized to a ketone body that can be excreted??? Also, basically every single large study that's ever tried to correlate diet to overall health or mortality comes up with the same conclusion, which is that the more plant protein you eat, the longer you live, whereas meat/dairy and especially egg protein kills you faster (lots of caveats in there). Overall, keto seems dangerously unhealthy to me, although I don't have evidence to support that beyond the epidemiology and a few anecdotes about people going nuts on keto. I think the only nutritional advice anyone really needs is: eat more plants.
Thanks for the biology! It's a thing that never really caught my interest in school, and probably my weakest area of understanding. The core thing about Keto that you kinda got wrong is that it is primarily leafy greens - like, 70% of your diet - and the rest is fats and proteins in various forms. Like the Adkins Diet, you eat a "palm-sized" bit of protein with a big ole salad that dwarfs the protein. So it is basically a heavy-plants diet, but fortifies that with specific proteins, and no carbs. The interesting part about the low carbs, is that plants store their energy as sugars (carbs) in their roots. So in Keto the shorthand is to eat "above-ground vegetables; mostly the leaves". It's a little weird to get used to, but, in essence, you have a steak salad as much as possible: a bed of fresh spinach with crunchies like celery and cucumber and onions, with slices of really nice flank steak on top, and a light vinaigrette dressing. (Which, to me, is pretty much a meal I would eat every day, for every meal, as often as I could! :-) Over the years I have been doing it, I have tweaked and adjusted it according to my body's particular needs, and I would no longer call food intake "Keto", the health benefits I have seen from eating this way have been too numerous to count. Which is, honestly, like DUUUH... of COURSE eating more veggies, fewer sugars, and zero "processed foods" is going to make you healthier. But the way that worked for me to get to that kind of diet was via the phenomenal weight loss I encountered the first year. 40 pounds lost, and have been kept off for close to 3 years now. Better sleep. Sharper brain and thinking. No afternoon crash. Zero reliance on coffee to get at it, in the morning. Keto for me was just the path to the healthy diet we all know we should eat. The early rewards kept me diligent, and the long-term effects have kept me thinking the "Keto way" ever since.