Hey guys, we’re back with the follow-on to last week’s video on fasting and autophagy.
And this one’s for you science nerds.
If you want wrap your brain around the nitty-gritty of how your body reacts to the progressive stages of a fast,
how it shifts from burning glucose to using fat for energy,
and how you can tap into that knowledge to track your own progress,
then you’re gonna love this video. Be right back.
OK, first off, I need to get some housekeeping out of the way.
Creating videos for this channel has been taking up way too much of my time.
I’ve got some other projects, like creating a longevity course,
that I’ve been trying to get off the ground, but these videos have taken priority.
So, I’ve decided to temporarily devote more time to those other projects.
Which might mean that videos for this channel might not post every Tuesday.
I’ll be posting new videos as often as I can,
but I’ll be putting more emphasis on putting out quality videos,
rather than putting one out every Tuesday.
This is the 3rd video in the Balancing AMPK & mTOR Pathways,
and the second part to the video I posted last week.
In this video, we’ll be going over the stages of a fast in detail
and trying to cover everything that happens during an extended fast, hour-by-hour.
Then I’ll share my own experience with fasting.
and I’ll try to relate readings that I took on my Keto-Mojo meter to the various stages of fasting.
Now first, I want to re-emphasize once again, that I’m not a doctor,
and that everyone should consult with their physician before embarking on a fast.
If you are diabetic, maybe you shouldn’t be fasting.
And if you have any form of metabolic syndrome, you should most definitely consult with a physician.
All right. We’re going to start off by taking a deep dive into the stages of a fast.
As you move through a fast, a lot of different things can happen,
and these events can be roughly grouped together to form stages.
But nobody agrees on what the stages of fasting are.
One source lists 3 stages, another lists 6 stages and yet another lists 10 stages.
So please keep in mind
that what particular stage you’re in doesn’t matter nearly as much as what’s actually going on.
But what’s going on can depend on a lot of things, like how ketone-adapted you are,
whether this is your first fast or, like me, you’ve been doing intermittent fasting for 10 years.
It can depend on how much fat you’re carrying around,
how many calories you consumed in the last meal that you ate before you began your fast.
It can also depend on your metabolism, whether it’s fast or slow.
Now, this chart represents glucose usage over time.
How much glucose is being metabolized, in milligrams per hour.
Everyone’s different, and this chart is just an approximation of when the stages begin and end.
You’ll notice that the stages overlap, and the further you get into a fast, the more they overlap.
When you start a fast, you’re in a fed state, also known as the Post-Prandial or
Gastrointestinal phase.
This is when you’re still digesting the food from your last meal,
and your glucose levels are on the rise.
This phase usually lasts anywhere from 4 hours to 8 hours in.
All the tissues in your body are using glucose for energy,
and excess glucose is being stored in the form of muscle and liver glycogen.
And these rising levels of glucose will stimulate the secretion of insulin.
But as you progress through stage 1 and exogenous calories get used up,
glucose from exogenous sources drop
and your body begins depending on your glycogen stores for glucose,
through a process called glycogenolysis, which converts your stored glycogen back into glucose.
The next phase starts whenever all of the food from you last meal has been metabolized,
after the first phase has finished, and the 2nd phase can last until 18 to 24 hours in.
The exogenous calories have been used up and your blood glucose levels start to drop, increasing insulin sensitivity.
Now, I’ve heard of this phase called the Post-Absorptive Phase,
and I’ve also heard it called the glycogenolysis phase.
It’s during this phase that you might experience dizziness, drowsiness,
brain fog and a sense of uneasiness.
All tissues in your body, except for the liver, are still using glucose for energy,
with the muscles and adipose tissue getting about 80% of their energy from glucose.
However, instead of coming from your food, most of this glucose now comes from your glycogen stores.
But not all of it.
Your body is now beginning to fire up a process called gluconeogenesis.
As the body become more and more unable to support normal glucose levels from exogenous sources,
it begins to synthesize glucose from non-carb sources such as lipids or fats, and amino acids, which are proteins.
While this process can initially start by converting a small amount of muscle protein into amino acids
and then into glucose,
it quickly shifts into using aminos from other sources like skin, cellular debris and pathogens.
Your body really wants to preserve your muscle mass
and is actively looking for sources other than muscle protein.
During this phase, your body uses up as much glycogen from storage as it can.
Your liver is converting that glycogen into glucose.
As the glucose that’s available from glycogen storage begins to drop,
and the glucose that’s available from gluconeogenesis begins to rise,
the total energy obtained from glucose remains fairly constant throughout the phase.
Cortisol and adrenaline levels may rise initially during this phase, as a stress response,
but they will soon drop back down.
Insulin also begins to drop during this phase, leading to a rise rise in insulin sensitivity
and in a corresponding rise in insulin’s antagonistic hormone, glucagon.
Also during this phase, your body starts to break down fat for utilization as energy.
Triglycerides are broken down into three molecules of fatty acid and a molecule of glycerol.
In the liver, most of the glycerol is converted into glucose,
but some of it gets converted into ketone bodies.
So it is during this phase that ketosis begins, but it is really just starting up.
Your muscle and adipose tissue are only getting about 20% of their energy from fatty acids or ketones.
Once the 2nd phase wraps up around 18 to 24 hours in,
the “Gluconeogenesis” phase kicks in, and this phase lasts until somewhere around 36 to 48 hours.
That means that in the first day,
we’ve likely moved through 2 stages of fasting and are into the third.
The third stage starts maybe a little before the end of the first day,
and continues until about the end of the second day.
Now, gluconeogenesis started in the last phase, but this is where it really fires up.
Most of the glycogen stores have been used up,
and now the body is depending on glyconeogenesis to provide most of the glucose.
All of your tissues except for the liver are still using glucose for energy,
but not as much as before.
Your muscles and your adipose tissue are only getting 50% of their energy from glucose.
Because the breakdown of fat is also on the rise, and fatty acids are providing the other 50%.
As fat gets broken down into fatty acids and glycerol,
your liver is converting less of the glycerol into glucose and more of it into ketone bodies.
Your body is transitioning from burning glucose to using fat for energy.
But a couple of other things are starting to happen.
Your human growth hormone levels (HGH) are on the rise,
and this promotes an anabolic state in your body.
This will continue throughout the fast
and will really come in handy after you break your break your fast,
refeed, and provide new sources of protein for the repair processes that will really kick in after you break your fast.
The other thing that starts to happen during the gluconeogenesis phase is Autophagy.
Somewhere around the beginning of stage 3, somewhere around 24 hours,
is when most experts agree that autophagy is finally triggered and it starts to take off.
Your insulin levels are dropping,
your glycogen stores are just about used up,
and your glucagon, HGH and AMPK levels are on the rise.
As AMPK goes up, it begins to shut down mTOR.
All of these conditions are ripe for autophagy.
Somewhere around 36 to 48 hours, that’s about a day and a half to two days in,
you enter the “Ketogenic” stage of your fast,
and this stage lasts for approximately a day.
All of your glucose is now coming from gluconeogenesis, but it’s not as much as it was.
Somewhere around day 2, it starts to fall off and then stabilizes.
Only brain tissue, red blood cells
and tissue from the center of your kidneys, called the renal medulla, are still using glucose for energy.
But the brain is starting to use ketones.
Your muscle and adipose tissues are now deriving 100% of their energy from fatty acids and ketones.
This is the phase when your body has really shifted to using fat for energy.
And your liver has shifted from converting glycerol into glucose
to converting it into ketone bodies.
This is due to the large amount of energy required by the brain,
the limited amount of glucose available,
and the inability of fatty acids to cross the blood-brain barrier.
So the brain’s running out of energy, and ketones are what’s available.
But as it turns out, that’s a much better fuel for the brain.
Ketones are anti-inflammatory,
and when your brain uses ketone for energy instead of glucose, which is highly inflammatory,
it promotes the production of Brain-Derived Neurotrophic Factor or BDNF.
This restores mental clarity and nourishes the brain with high-energy fuel.
It’s during this phase that brain fog lifts and cognition improves.
Finally, as your body starts to break down fat, it also detoxifies.
Your body uses fat to store toxic metals and other toxins, to keep them from harming the body.
When fat is broken down, these toxins are safely expelled.
After about 3 days of fasting, when-things-happen really starts to vary among individuals,
so I’m not gonna be to very precise about the timing.
After you’ve been fasting for about 3 to 5 days,
your body enters a phase that some call the “Protein Conservation” phase.
This is when really good things start to happen.
Insulin levels are low and now considered to be normal.
Cortisol and adrenaline are also low.
Cholesterol and triglyceride levels are dropping.
Glucagon levels are high and your human growth hormone is 5 times it’s normal level.
Hormones are now stabilized and you enter a state of homeostasis.
You body is now relying primarily on fatty acids and ketones for energy.
Like your muscle and adipose tissue, your brain tissue is now ketone-adapted
and is using ketones for 80% of it’s energy needs.
Autophagy is in high gear, AMPK levels are high and mTOR has shut down.
Once you reach about 5 to 8 days,
and for the next week or so, your body is fully adapted to fasting and burning fatty acids and ketones.
You body has fully entered a healing mode.
Your digestive processes are shut down are taking a rest from the common, daily stressors of digestion.
There are fewer free radicals floating around and oxidative stress diminishes.
But fasting causes another kind of stress, similar to that of exercise.
And your body reacts to this stress in a similar way to exercise,
in that it becomes more healthy and better able to handle the stress of living.
Your immune system starts to regenerate healthy, new immune cells,
pushing your immune system through the roof.
Since it’s the immune system that removes senescent cells,
this can be another tool in your defense against aging
…not to mention staving off diseases.
This is when you start to see really dramatic improvements in cognition.
You experience elevated mood, increased energy levels
and a type of clear-mindedness that is unique to fasting.
This is a result of using ketones to fuel the brain and the rising levels of BDNF.
We’re now entering the realm where you really need to be under the care of a physician
if your want to push your fast further.
After about 2 weeks, you’ve reached a state of balance.
Other than the ongoing cleansing and healing, not a lot happens going forward.
A small amount of glucose is still coming from gluconeogenesis,
which is being used primarily to power the red blood cells and the renal medulla.
The brain is only using glucose for about 20% of it’s energy needs.
Your body is now fully fat-adapted
and is using fatty acids and ketones for almost all of it’s energy requirements.
The main thing that’s going on here is healing and repair.
The longer you can extend your fast, out to about 30 days,
the more healing and cleansing that will occur.
Alright, let’s talk about my own experience with fasting.
As many of you know, I’ve been doing intermittent fasting for about 10 years.
Most of that time, I’ve been doing a 16/8 fast…
Fasting for 16 hours and then eating during an 8 hour window.
For the last several months, I’ve been decreasing that eating window,
and now it’s down to about 4 to 6 hours.
I’ve also done several extended fasts and the intermittent fasting has really helped with those.
But even with that, I’ve noticed that as I progress,
each fast gets a little easier to do, and lasts a little longer.
I’ve also noticed that when I’m eating a ketogenic diet, that also helps with the fasts.
I’m now at the point where a 5-day fast is pretty easy.
My goal is to get to the point where I can do a 2-week fast.
So, we’ll see how that goes.
What I want to do here is to take you through one of my typical fasts,
and give you my glucose/ketone index readouts during the fast,
and try to relate that to a stage in fasting.
As you may remember from my last video, the glucose/ketone index, or GKI,
is simple a ratio of your blood glucose level to your blood ketone level.
As I mentioned earlier, everyone starts out a fast in a fed-state.
Now, I typically eat at the end of the day,
so my last meal was around 10 PM and I started out with a glucose ketone index, or GKI of 19.6.
Actually, that’s pretty good.
My glucose was at 5.8, and my ketones were at 0.3.
Typically, I usually start with a GKI around 50 or 60.
But I was already doing a ketogenic diet, so my ketones were higher than the typical reading of 0.1-0.05.
My glucose was where it typically is, so it was the higher ketones that gave me a lower GKI.
The next morning, at 10 hours in,
my glucose had dropped to 5.1 and my ketone had risen to 0.4, giving me a GKI of 12.7.
Still not in ketosis.
I figure that I was ending the gastrointestinal phase
and starting the glucogenolysis phase, or post-absorptive phase.
My next reading was at 24 hours.
Glucose was at 4.9 and ketones was still at 0.4, so my GKI was 12.3.
Not much movement. This was to be expected.
Although my glucose from glycogen stores was dropping,
my glucose from gluconeogensis was on the rise,
so my total glucose was about the same, and my ketones hadn’t really kicked in yet.
I figure that I was near the end of the post-absorptive phase
and was about to enter the gluconeogensis phase.
I don’t really thing that I was in autophagy at this stage.
Next reading was at 48 hours.
Glucose was still about the same, at 4.7,
but my ketones had doubled, at 0.8, giving me a GKI of 5.9.
I was finally in a moderate state of ketosis, which meant that I was probably entering the ketogenic phase.
My glucose had stayed pretty level for the last 36 hours, which was normal,
but I was definitely in a fat-burning mode.
And I’m pretty sure that autophagy had finally kicked in.
At 60 hours, I took another reading and my glucose had actually gone up a scosh, at 4.8.
My ketones had doubled again, at 1.7.
This gave me a GKI of 2.8, which puts me in a high level of ketosis.
The next reading was at 72 hours, and while there wasn’t a big change in my GKI,
there was a drop in my glucose level, so I figure that I was still in a ketogenic phase.
Glucose was at 4.3 so that was significant,
that was the biggest drop in glucose since I started,
so I figure that I had just about used up most of my glucose resources from glycogen
and was running on pure gluconeogensis.
I expected my glucose to stay about the same for the rest of the fast.
But my ketones were still 1.7, giving me a GKI of 2.5
So, not much change overall.
But 10 hours later, at 82 hours into my fast, things really started to move.
My glucose was still 4.3, no surprise there,
but my ketone had doubled once again, rising to 3.0 for a GKI of 1.4.
I was now in the maximal level of ketosis,
and I figure that I was now in the protein conservation phase.
It had taken me 3 days and 10 hours, but my body was now fully adapted to using fat as fuel.
This was where I wanted to be.
By 96 hours, my glucose had dropped to 4.1, not a big change,
but my ketones had risen to 3.9, for a GKI of 1.0.
At 108 hours, glucose was still at 4.1, but my ketones were also at 4.1, so my GKI was still 1.0.
My final reading was at 112 hours
and my glucose had dropped to 4.0, not a big change,
but my ketones had risen to 5.5, a really big jump, putting my GKI at 0.7.
I had just spent 30 hours in maximal ketosis,
where I was utilizing fat as my primary source of energy,
autophagy was fully ignited and I was clearing out a lot of waste products
and preparing my body for a major regeneration and rejuvenation phase when I ended the fast,
did a re-feed and provided my system with the resources that it needed to start making repairs.
Whew! We got through it.
I hope you guys enjoyed this video and thanks for hanging in there until the end.
Check out the rest of the videos in this series on balancing AMPK and mTOR, right here.
That’s it for me. Until next time, I’m outta here.