My sleep patterns get completely messed up on my fasts. I'll sleep for 4 hours and then wide-awake. I switch back to normal eating and I get a full 8hrs sleep that night.
It made me think I was doing something wrong but then the more I thought about it, maybe I just don't need more than those 4hrs of sleep when I'm fasting.
This was mentioned in Matthew Walker's book "Why We Sleep." Ghrelin and dopamine levels are high which keep you awake. It is suspected to be an evolutionary boost that you are alert more in order to find food.
The actual feeling of being hungry doesn't persist when fasting.
There's a phase, but it passes. It's fairly well known that operating in fat-burning mode puts one in a different head space. It's one of the features commonly touted by advocates of the ketogenic diet, which experientially is very similar. There's a mental alertness and clarity, in my experience it's accompanied by elevated energy levels as well.
It seems to me that it arguably benefits the species to fire on all cylinders in periods of scarcity, as it improves chances of locating food before starvation. In periods of plenty, there's no urgent need, so a more conservative baseline mode of operating is advantageous as it saves fuel as fat for the scarcity periods. Humans didn't evolve with grocery stores and refrigeration, scarcity was a regular and mortal issue, our bodies evolved to address it.
Whenever I fast it feels like I'm on a sustained upper of sorts, once the hunger phase passes. It's kind of like being permanently wired, keyed up, sometimes a little over eager. And yeah it can interfere with going to sleep, similar to drinking coffee late in the day. It's not a problem in my experience if the day is spent being physically active though. Which I think makes perfect sense if we accept that this is an evolutionary trait improving odds of finding/killing a meal. We're supposed to be actively locating next meals when awake in this mode, not sedentary.
I've found it to be a valuable life hack and would argue everyone should at least be familiar with the experience enough to know the initial hunger phase is short-lived and what follows afterwards isn't unpleasant at all, and actually advantageous in some aspects. There are many activities where not having to bother with food/cooking/eating for a few days is game-changing, this combined with elevated energy levels and alertness as well? It's like magic. I never take food on day hikes anymore for instance. Instead I don't eat for the 24-hours prior and just bring water. I'm well clear of the hangry phase, and feel like running the entire thing (and if I'm alone, often do), it's unreal. There's plenty of fat on my person to last weeks of fasting.
I'm a very experienced faster, been doing it on and off for 17ish years; my longest fast was five days. It's not true (for me) that "the actual feeling of being hungry doesn't persist when fasting."
When I fast I'm fucking hungry, and that doesn't go away, though it becomes a bit more manageable; the intensity of the hunger waxes and wanes.
>It's fairly well known that operating in fat-burning mode puts one in a different head space... There's a mental alertness and clarity, in my experience it's accompanied by elevated energy levels as well
Definitely never experienced anything like this. Quite the opposite really.
Though I do enjoy the sheer uncomfortableness I feel when fasting in a weird sort of way, almost like feeling it makes the feed state feel so much better.
Maybe there's a significant diet/lifestyle component? For example I don't derive much of my happiness from the food I eat when not fasting. I have known multiple people over the years who eat almost exclusively comfort foods and it's the only thing keeping them out of depression. They would probably be very agitated by a multi-day fast.
My diet is pretty restricted in general, there's not a whole lot missing after the transition into fasting in terms of my daily life experiences and rewards. It's mostly a small burden has been removed.
I'm with you. My mental alertness and clarity during fasting is me being hungry, angry and impatient. When the hunger wave goes away, I'm left with angry and impatient. So yes, productivity rises.
Maybe when people who are naturally aloof and easy-going are fasting, they get alertness and clarity. I'm already a somewhat aggressive person maybe it pushes me a bit too far.
My coworker and I are very good friends. When went on a restrictive diet for a month, we both were hangry all the time and eventually she stop talking to me (even though I'm her boss). When we look back at that month, we can laugh, but at the time we had no idea we acting like that. A third coworker just rolled her eyes at us because she knew what was going on.
Yeah, one of the reasons I switched to a low-carb, sometimes zero carb, diet is for that constant "up" feeling.
I was about to add that I've never tried fasting, but I just realised that a lot of people do this "intermittent fasting" stuff where you don't eat for sixteen hours. I normally eat dinner at 5:30 pm and breakfast around 9 am, so I guess I'm almost there? I've never noticed any real benefits though.
I wonder, is it that your body is worried about getting food and will cut off sleep to give you more time to find it, or is it that the build up of chemicals like adenosine(which seems to play a role in sleepiness, and gets cleared out during sleep.) in the body has slowed so that less sleep is required?
Same here. Worse, I've even observed my body has difficulty producing enough heat to warm my bed. Also, when I do an important sport effort I often have troubles sleeping the next night.
It made me think I was doing something wrong but then the more I thought about it, maybe I just don't need more than those 4hrs of sleep when I'm fasting.