A 24 hour fast for a mouse is like a 2 week fast for a human. Hard to say that this would result in the same outcome for humans. I've also read that lab mice are nothing like normal mice.
This has got to be HN's favorite intermittent fasting meme. It combines a "well actually" with a false sense of mathematical precision - both are crack for HN. But it's more false than true.
The truth in it is that mice lose a greater percent of their body mass in the first 24 hours. Also mice will die if deprived for food for ~5 days. So at 24 hours, they're much closer to death than a human.
But that's not really what we care about with IF. Most people care about the metabolic transitions prompted by fasting,[0] which are strikingly homologous across mammals. The variance that does exist is pretty well captured by the models that underlie those metabolic stages.
This article is about something going on in the brain, which is harder to assess in humans for obvious reasons. But one of the big benefits of fasting that kicks in around the 24 hour mark is macro-autophagy. We know macro-autophagy is occuring in the brains of mice by 24 hours [1] and we know that macro-autophagy has a similar time course in humans and mice in the tissues we're able to sample.[2]
I mean, based on my extended fasting experience I'd say it's something that's worth exploring. I can't speak specifically to memory, but the mental clarity whenever I fast longer than a few days tends to be awesome.
A seven day fast is something I'd encourage everyone who's otherwise healthy to try at least once in their life.
I tried fasting Tuesdays and Thursdays for a few weeks in college. A couple weeks after I stopped I had severe and sudden dizzy spells for months. I’m not willing to try again unless I go hand in hand with a doctor.
That sounds interesting. Do you have any tips or guides to get started, or is it more like “just stop eating”? I have never fasted for more than some hours before.
I'd start with "just stop eating" and then solve for any issues that pop up for you because people have a lot of different reactions. For me, I do alternate day fasting... sometimes 2-3 days of fasting in a row. I had some common issues such as not being able to sleep and diarrhea while fasting. So instead of 0 calories, I eat a bowl of oatmeal (high fibre) on my "fasting days". Also, when weight training while fasted I'd feel so light-headed I'd have to stop. But I fixed that by drinking 1 bottle of Gatorade (some calories + hydration + electrolytes) before exercise. You'll just have to find what works for you. Other patterns are 5:2 (2 days of fasting) and one-meal-a-day. Sometimes after a break from fasting, I'd get too hungry the first day back on fasting so I'd ease into it with one-meal-a-day.
You should have some salts to keep well hydrated, also be healthy and don’t have any problems like diabetes, or with your kidneys. Anything over 36-48 hours would be better to check with a doctor first.
The only times I've got dizzy when '24h water fasting' are when I've been eating normal/high amounts of carbs in my diet around the fasts.
I've been doing a few days/week of 24h water fasts again, but on a very-low-carb diet, and can report no dizziness whatsoever.
An additional benefit (also mentioned by others) is that I don't have any insatiable hunger pangs on the water fasts (which I did when I attempted them on a normal/high carb diet).
Obviously your mileage may vary (etc etc), but for me, it's all about removing carbs. It's the difference between water fasting being (honestly) easy .vs. A herculean feat that I couldn't manage.
I wonder if there is any benefit from shorter periods, since I do not have the body fat to easily sustain a 2wk fast... also sounds like a good way to lose a lot of muscle?
The body protects its nitrogen. You do lose some lean tissue mass but its relative share goes down with fast time (as long as you have the fat stores) and compared to a lean person it's less from the onset.
