If you’re constantly moving sugar is a necessity for maintaining glycogen. There’s nothing inherently wrong with any food type, it’s all about context.
Human body prefers ketones as a source of energy. But glycogen is faster.
My simplified mental model is like this. Ketones are normal gasoline. And glycogen is racing fuel (ethanol). If you run a stock car on racing fuel it may start and drive for a while but it’s damaging the engine and creates unnecessary wear.
Ketone supplements have been available for a while, and nobody was able to show any benefit of using them. 100% snake oil.
If on the other hand you want to produce ketones endogenously, you basically have to put your body in a state of starvation. It’s not really gasoline then, more like burning the passenger seats as fuel so you can arrive at the destination.
Also not really supported by anthropology or science.
The only folks who think like this are folks who choose to believe weird dietary theories to support a pre chosen stance, like the carnivore diet or some form of excess(in the form of self-care/diet)