Huh, interesting. I’ve generally heard the recommendation of fasting beforehand instead.

Fasting is the fastest (heh) way to get into a ketogenic metabolism! It's true. I'm just optimizing for minimal cravings when people switch.

I suspect the quickest way to switch is to do intense exercise between the last non-keto meal and the first keto meal. It’d burn through a lot of the glucose glycogen stored in the liver and muscles, forcing the liver to release ketones immediately instead of waiting a day for them to deplete normally. Though you’d probably get the shakes from hypoglycemia in the meantime.

Fasting + intense cardio would deplete the glycogen reserves it's true, but gluconeogensis will replace them. I think the key is to just keep insulin levels down and give the body enough time to adapt. Some people struggle with cravings, some people temptation, some people just need to get it done - so they will all have different strategies

For me, I’ve just switched to keto foods and let the switch happen on it’s own over the course of a few hours. No need to rush it. Thankfully I have a harder time going off of keto than getting on

That is awesome! Well done.