So. Starving yourself. Sounds like great fun right? You’ve been told for years, assuming anyone’s bothered to explain it, that not eating sends your body into starvation mode and will tell your metabolism to hold on to every shred of energy you give it.
Turns out… Lies. Filthy dirty lies. Sort of. As always, it’s an annoying version of “it depends” and needs context.
This is another conversation that needs to start by talking about acute stress and chronic stress.
The short version is: starving yourself is chronic stress. Whereas fasting is acute stress. Chronic is bad. Acute is good. Hormesis is winning.
But now, the long and nerd-ily detailed version.
What do you think your body does when it thinks its going to starve? Even more, what does your brain do? Mostly, it freaks you out and dumps a whole bunch of cortisol and adrenalin to give you energy and drive to fix this very unwelcome situation. This is good, for a little while, because that cortisol and adrenalin helps move energy (like stored fat…) and nutrients to body parts that let you find/catch/cook/open the microwave/drive to the restaurant to eat said food.
It's when your body gets the idea that this starving is going to go on for a while, weeks and months kind of thing, that it decides to hold on to all its energy you might be putting in because its really not sure when this stressful state of affairs is going to end. Basically, you get fat because your body needs to protect itself from the winter and potential white walkers that are coming…
But, what happens when you fast for a relatively brief period of time knowing full well that there’s a brightly shining food light at the end of this “starvation tunnel”? Honestly, great stuff. Amazing stuff. Maybe the coolest of stuff human bodies are capable of. With the obvious exception of growing a new human. That is very cool and seriously underrated. Fist bump, ladies.
I keep dropping the word autophagy into previous blogs, but now it finally gets its time to shine!!!
There is a few different types of fasting, so I’ll start from the beginning and work my way up.
Intermittent fasting is the most common and manageable version. It’s what I do. Usually it looks like 16 hours of eating nothing (I say and mean EATING, you should still definitely drink water, and can drink green tea and black coffee without mucking your fast up too. They can even help the fast), with an 8hour window of eating what you normally would. The 16hour phase is the time it takes for the body, typically and generally anyway, to start to initiate the processes that make fasting valuable. Because you aren’t diverting effort, energy and metabolic process to processing food constantly, your body can actually do some awesome housekeeping.
In this 16 hours, you drop your insulin levels, increase your sensitivity to it (which means you’re less likely to store energy, especially fat, AS fat when you do eat), you go into ketosis (which is the shortly worded version of how you prime your body to burn its already stored fat), your gut gets a breather and can invest in making new hormones and keeping your biome up to scratch, reduce systemic inflammation (which is the root of all evil when it comes to pain and disease, in most cases at least), a heightened release of HGH (human growth hormone) to ensure that you don’t lose all your gains when not eating much (yet another future blog subject) AND potentially autophagy. There’s just too much cool stuff about autophagy to not make it into its own blog post, but I’ll try to do it justice in a paragraph.
When your body doesn’t have incoming food to deal with, it goes into efficiency mode. It gets really “survival of the fittest” on a cellular level. You have more cells than you need floating around on you. Some of them suck, some are dying, some of them are taking up space. So, your systems get to pruning off those unneeded cells. Breaks them down into ammino acids and uses them to feed other, cooler cells. Keeps them running and humming. So, when you do eventually eat, you ONLY feed the cooler and hotter cells, which keeps you strong and healthy and functioning sweetly.
Best bit? Those crap cells that got chewed up in the fasting revolution? If they divided and made new cells once they’d been fed energy, they make new, crap, mutated cells. Those mutations are typically how cancers start. Not exclusively, but often enough to really really matter. Kind of why its important to bin them… Again, pretty short version, but I promise I’ll go into more detail next time I properly talk about autophagy. And sorry, that’s was two paragraphs. Couldn’t help it…
Anyway. On with the fasting!!!
Because of this period of efficiency, when you do eat again, you process and absorb the nutrients much more effectively. Used, not stored. Which, for the most part, means you can eat the same amount of food in a lesser amount of time and not suffer fattening from it. Your body practically encourages you to eat more food! But take it easy. Everyone knows what happens when the rebound effect of a diet takes hold. Sorry to say, donuts and ice cream aren’t great for you, post fast or not.
There are a few different combinations of fasting times, but it’s all academic really. Mostly longer, but the longer a fast the more those benefits I mentions really have a chance to do more cool stuff. You can do a 20/4 fast, sometimes called an OMAD (One Meal A Day), which makes a combination of time restricted eating and calorie restriction, both of which help use fat stores and initiate those reactions the body has.
Or there’s 24, 36, 48 or 72 hour fasts, all of which just mean you send more time in those states to make use of those systems (I’ve heard of people doing longer ones, like 9 day therapeutic water fasts, but that’s pretty hardcore). Obviously, there’s a fair amount of discipline when considering these kinds of fasts, progressing yourself to these sorts of fasts is a practice in the mental discipline on top of the physical tolerance and adaptation you make.
There’s vegan fasting too, which is done to give the digestive system a rest from processing all that nutrient dense meat. Because that can take some doing, so a little bit of time off from that can help with the minimising of some potential inflammatory responses just general heavy duty processing can cause. Not really interested in engaging that whole vegan versus omnivore conversation, suffice to say there are pros and cons and value for individuals on both side of the fence and leave it at that.
From an evolutionary and hunter gatherer standpoint, fasting makes a lot of sense. The human body needs systems in place to ensure that if can’t find or catch food back when we were all called Zug or Gog, you need to be able to do the same thing the next day to try again. Adrenalin to keep the brain sharp enough to outthink fast, hard to find and tasty stuff, cortisol to move energy around the body to chase the stuff, and the human growth hormone so you have the ability to recover from the physical strain of your chasing efforts in case you didn’t catch something today either. So, fasting is what we do to take advantage of those epic old backup systems.
As always, there’s nuance and fiddly bits and individual preferences and individual reactions and physiological predisposition and blah blah blah. This said, if it’s something you’re interested in, there is a version for you that will work. Just need to play the fasting field a bit.
Be kind, be smart, be your best you. No barfights.
“If a man has nothing to eat, fasting is the most intelligent thing he can do.” Hermann Hesse
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