It seems to me that all of the studies on autophagy have been done on mice. This is just my opinion, however I don’t think the timeline is anywhere near the same in humans.
To me there is something magical that happens around the 5-7 day mark and continues up until I break my fast. I am sure other fasters can attest to this.
Seriously, how does 3 days of fasting for a mouse translate to a human? I don’t think the true benefits occur until well into a fast.
Mice lose a significant portion of their body weight after 48-72 hours of fasting. It’s on the order of 20-30%. This alone tells you can’t compare effects on the same time scale. That said, my understanding is that autophagy is a spectrum. It’s not like an on/off switch. You probably have some cells doing autophagy right after a meal, and some that will never do it. Three days could very well be a threshold where you can say “yeah, you probably have some autophagy going on right now.”
I do enjoy the twiiter account https://twitter.com/justsaysinmice which clarifies every dramatic headline about new drug results or diets… in mice lol.
Might have to wait till 2023 for results from this study Time Course for Fasting-induced Autophagy in Humans.
Right, we know that mice enter ketosis four hours after a fast starts. For humans it’s something like 12 or 18 hours. Also mice are nocturnal, and their normal eating habit is at night whereas humans have the best health when they eat during daylight hours. There’s no one-to-one comparison so I agree completely that timelines for autophagy for humans are speculation. But we do know certain substances lower autophagy so we can at least know if we are avoiding those substances for long enough we should get some benefits. It’s also harmful to have too much autophagy, but I think most people don’t have to worry about that risk. If someone is prone to severe hypoglycemia, they do have to watch their blood glucose because that’s one instance when autophagy can be kind of harmful. I’ve read research that brain cells can be marked for death when blood glucose gets too low, and when the person eats again, that is the point when the brain cells get destroyed.
We can’t observe autophagy in humans because we’d have to surgically remove muscle and/or organ tissue to put under a microscope. Also, 3 mice days is about 4 human months (according to one paper), so I wouldn’t assume our 72 hour fasts have the exact same effect. I’d just go off of what you observed individually; that adrenaline and euphoria. I get that rush around 3-4 days. Hope that helps!