>So, it’s pretty clear that any spike in insulin, even ones from non-sugar sweeteners, kicks you out of ketosis, and thus essentially breaks your fast.
That is not clear. Ketosis does not equal fasting and a little sugar or sweetener does not kick you out of ketosis. You don’t need to fast to be in ketosis, just eat under 20g carbs a day.
As to the autophagy, first, it is always happening. Fasting just ramps it up. Second, it’s not well studied. We know that mTOR activation can slow the acceleration that fasting gives. Protein and carbs activate mTOR, fat does not. That’s why there’s some debate about if eating pure fat (like coconut oil) instead of a straight fat might still get you the benefits of autophagy ramp up.
But nobody actually knows, it’s all conjecture.
I think the answer to this question is that we just don’t know. We really don’t have enough research on autophagy in humans to answer most questions about it. We are making a lot of assumptions based on animal models, mostly rodents.
I have no idea where this mistaken belief of fed vs fasted as some kind light switch mechanism of all or nothing comes from. Human physiology and specifically hormonal response, secretion, etc. is not even remotely this simplistic. Though I am sure medical students around the world sure wish it was.
It would make more sense to instead view it as a spectrum which responds to a plethora of stimuli to varying degrees. There is no “clock”. Dose dependent would be another good way of looking at it. You really need to wrap your head around this reality first before further explanation will resonate with you.
Also bear in mind that Ketosis is not required for weight loss. How do you suppose that weight loss routinely occurs in people who do not adhere to any fasting protocol whatsoever and eat 250+ grams of carbohydrates per day?