The ability to flip flop between fuel sources without all the hell. Eat Fat, burn it for fuel. Eat Carbs burn them without feeling like you’re hungover afterwards. Realistically they way we should be.
You’ll find many mixed ideas on it (here) but it’s pretty popular and should be. Purists think it’s all about being able to cheat without the carb hangover, but it’s not at all. We talk of how our metabolisms are so screwed up that we can’t burn fat for fuel anymore which is the case for most of us when we start. But then we do super strict keto and keep carbs out for so long that we recreate the exact same problem just with carbs. Our metabolisms are designed to have multiple fuel sources, so why it’s ok that we always have to have one of them basically damaged is crazy, at least to me. Took me a while to think of it that way, I was at one point a card carrying Keto cult recruiter.
What’s different when you’re flexible aside from the obvious is If I eat near keto all week, then my kid wants a pizza, I used to either eat something else or eat my own homemade concoction or a fathead or something, clearly not even remotely as good as the real thing. But the “payback” wasn’t worth it. I’d feel hungover the next day, retain tons of water aside from the glycogen reload etc. Now If I do that I eat the pizza and that’s it. No payback, no pain, no water, no nothing. The next day I’ll be making ketones again once I burn it off. Not some drawn out long term thing waiting to get “back into ketosis”. It just happens. If I eat a super fatty meal there’s no upset stomach or an hour on the toilet, my body just deals with it.