i think the whole concept of keto gets blown out of proportion.. your body uses whatever you feed it, simple..
I see people on keto forums likE OMG! i just had 0.001 ounce of sugar, am i out of keto??? jeez..
I eat like 400 calories from carbs, and maybe 2000 from fat, and another 1000 from protein, and if my BODY only burned fat when i was in keto, then id be either dead right now(since my body can only use the carbs/protein right)? or id be super fat from my body storing all that fat..
bottom line is your body eats what u feed it, i dont buy into that out of keto/into keto.. if u eat 100g of carbs for the day, and 500g of fat, your body will USE that 500g of fat for energy, plain and simple..
If however, you eat 1000g of carbs, and 1000g of fat, then i can see your body burning thru the carbs and storing the fat for later... but as long as you dont meet your requirements with carbs alone, your body will be in some state of fat burning mode for calories..