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.