Author Topic: Intermittent fasting. Health benefits?  (Read 2509 times)

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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #165 on: January 13, 2020, 11:29:05 PM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.
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Offline CarbShark

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Intermittent fasting. Health benefits?
« Reply #166 on: January 13, 2020, 11:41:08 PM »

In starvation mode the body does not easily discriminate from lean tissue that can be safely catabolized and lean tissue that cannot. That is where a potential danger lies.


You've been corrected on this twice already. 
Not with any evidence or citations. Just you and bachfiend saying uh uhhh


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« Last Edit: January 13, 2020, 11:43:45 PM by CarbShark »
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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #167 on: January 13, 2020, 11:43:13 PM »

In starvation mode the body does not easily discriminate from lean tissue that can be safely catabolized and lean tissue that cannot. That is where a potential danger lies.


You've been corrected on this twice already.  Now you're just lying.
Not with any evidence or citations. Just you and bachfiend saying uh uhhh


You're making (up) the (ridiculous) claim that the brain and other vital organs are catabolized during intermittent fasting.  The burden of proof is on you.  Good luck with that.
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Offline bachfiend

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Re: Intermittent fasting. Health benefits?
« Reply #168 on: January 14, 2020, 12:05:11 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.  The only thing that you can point to is loss of a trivial amount of muscle protein if the fasting is short term (up to several days).  Of course, it’s not a good idea to starve yourself for weeks or months.  How long is too long is the question.
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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #169 on: January 14, 2020, 12:10:21 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.
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Offline bachfiend

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Re: Intermittent fasting. Health benefits?
« Reply #170 on: January 14, 2020, 12:30:36 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.
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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #171 on: January 14, 2020, 01:03:38 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.


Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
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Offline CarbShark

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Re: Intermittent fasting. Health benefits?
« Reply #172 on: January 14, 2020, 01:16:50 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.


Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

But the body does not have an unlimited supply of broken down muscle.

So when that is depleted the body begins to catabolize lean tissue.


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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #173 on: January 14, 2020, 01:22:49 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.

Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

Yes.

Quote
But the body does not have an unlimited supply of broken down muscle.

Huh?  The process that goes on all the time that I was referring to is the breaking down of muscle protein, ie, proteolysis.  It is a constant process.

Quote
So when that is depleted the body begins to catabolize lean tissue.

Muscle is lean tissue.  We break it down every minute of every day.
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Offline bachfiend

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Re: Intermittent fasting. Health benefits?
« Reply #174 on: January 14, 2020, 04:38:16 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.


Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

But the body does not have an unlimited supply of broken down muscle.

So when that is depleted the body begins to catabolize lean tissue.


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But the body does have an almost unlimited supply of skeletal muscle which provides a very large reserve of protein available for the synthesis of glucose from gluconeogenesis.

When a person is severely starved, then yes vital organs such as the heart, begin to become affected, when the reserves in the skeletal muscle have largely been exhausted.

But the starvation has to be severe, as in the German soldiers besieged in the Battle of Stalingrad.  Or the Russian civilians in the siege of Stalingrad.  Severely starved individuals just dropped dead.  Or fell over, and couldn’t get up because their muscles were too weak, and just froze to death in the winter if there wasn’t anyone to help.
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Offline CarbShark

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Re: Intermittent fasting. Health benefits?
« Reply #175 on: January 14, 2020, 11:15:55 AM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.

Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

Yes.

Quote
But the body does not have an unlimited supply of broken down muscle.

Huh?  The process that goes on all the time that I was referring to is the breaking down of muscle protein, ie, proteolysis.  It is a constant process.

Quote
So when that is depleted the body begins to catabolize lean tissue.

Muscle is lean tissue.  We break it down every minute of every day.

The point is that without intermittent fasting the body is already using broken down muscle tissue along with dietary protein.

Take away dietary protein (along with all other calories from fat and carbs) the amount of glucose and derived from skeletal muscle breakdown alone may not be sufficient, especially if you add vigorous exercise (resistance training), which increases the need for protein and calories.


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Offline jt512

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Re: Intermittent fasting. Health benefits?
« Reply #176 on: January 14, 2020, 01:58:56 PM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.

Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

Yes.

Quote
But the body does not have an unlimited supply of broken down muscle.

Huh?  The process that goes on all the time that I was referring to is the breaking down of muscle protein, ie, proteolysis.  It is a constant process.

Quote
So when that is depleted the body begins to catabolize lean tissue.

Muscle is lean tissue.  We break it down every minute of every day.

The point is that without intermittent fasting the body is already using broken down muscle tissue along with dietary protein.

Take away dietary protein (along with all other calories from fat and carbs) the amount of glucose and derived from skeletal muscle breakdown alone may not be sufficient, especially if you add vigorous exercise (resistance training), which increases the need for protein and calories.


Enough for what?  Like I've been saying for 6 pages, on a 23-hour fast there will be more muscle protein used for gluconeogenesis then on an ordinary overnight fast.  If you are able to do vigorous exercise while fasting, then your muscles are getting enough glucose.  That said, I would not be surprised if anaerobic performance were impaired toward the end of a 23-hour fast.  I suspect that there are no NFL linemen who fast for 23 hours before a game.
« Last Edit: January 14, 2020, 02:01:06 PM by jt512 »
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Offline bachfiend

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Re: Intermittent fasting. Health benefits?
« Reply #177 on: January 14, 2020, 02:44:20 PM »
jt,

If glycogen depletion is as serious as you state, then humans would be extinct by now.  Periods of glycogen depletion as a result of famine are a natural occurrence in humans for most of human history.  I don’t think that glycogen depletion is as serious as you suggest.


I just responded to this.  See my post a couple posts up.

Yes, but your response isn’t convincing.  You’ve just stated it, referred to a few textbooks, nothing more.


Seriously?  Have you forgotten everything about biochemistry?  Nobody dies from glycogen depletion, because gluconeogenesis, ketogenesis, and other metabolic adaptations to starvation occur.  Source: Biochem 101.

That’s exactly the point.  Nobody dies from glycogen depletion because evolution has ensured that there are metabolic adaptations such as gluconeogenesis and ketogenesis.  It’s not serious.


I never said it was "serious."  I said it occurs, and stimulates gluconeogenesis earlier than you mistakenly believe.  It's CS who thinks it causes your brain to shrink.

So actually, we agree - it’s not serious?  I was going on your comment on January 7 when you wrote that muscle loss occurs throughout all days of a fast.  I interpret ‘muscle loss’ to be different to ‘loss of muscle protein.’  Muscle loss implies loss of muscle fibres due to severe atrophy and fibre death, and the muscle fibres might not be regenerated, which would have a negative impact on survival, particularly in difficult circumstances.  Loss of muscle protein is trivial, and an adaptive response.

Yes, then we agree.  Muscle protein is lost.  I don't actually know from which structures in muscle cells that protein comes from, but I did not mean to imply that the number of muscle fibers diminishes.  As far as I am aware, it is the same process that goes on all the time in muscle, but in early fasting it occurs at a faster rate while simultaneously muscle protein synthesis is inhibited; hence muscle protein is lost.
So it’s the same process that goes on all the time?

Yes.

Quote
But the body does not have an unlimited supply of broken down muscle.

Huh?  The process that goes on all the time that I was referring to is the breaking down of muscle protein, ie, proteolysis.  It is a constant process.

Quote
So when that is depleted the body begins to catabolize lean tissue.

Muscle is lean tissue.  We break it down every minute of every day.

The point is that without intermittent fasting the body is already using broken down muscle tissue along with dietary protein.

Take away dietary protein (along with all other calories from fat and carbs) the amount of glucose and derived from skeletal muscle breakdown alone may not be sufficient, especially if you add vigorous exercise (resistance training), which increases the need for protein and calories.


Enough for what?  Like I've been saying for 6 pages, on a 23-hour fast there will be more muscle protein used for gluconeogenesis then on an ordinary overnight fast.  If you are able to do vigorous exercise while fasting, then your muscles are getting enough glucose.  That said, I would not be surprised if anaerobic performance were impaired toward the end of a 23-hour fast.  I suspect that there are no NFL linemen who fast for 23 hours before a game.

I’m not particularly interested in doing anaerobic exercise in my exercise session towards the end of my 23 hour fast - I much prefer aerobic training.

But I’d correct your statement slightly:  If you are able to do vigorous exercise while fasting, then your muscles had enough glucose

Of your glycogen stores, 120 grams are in the liver, and 400 grams are in skeletal muscle (mainly in fast-twitch fibres, involved in intense short term exertions such as sprints and intense weight training) - which isn’t available for general use, but is used for muscle function.  So if the liver glycogen stores are insufficient to supply the brain and other tissues which are obligate glucose consumers (such as red blood cells), then gluconeogenesis will be necessary to supply the shortfall.  And the raw material will largely come from turned over protein from skeletal muscle.  And if you’re fasting longer than ‘normal’ (although ‘normal’ has been defined by food manufacturers and suppliers keen to sell as much of their products as possible to consumers who are already eating too much - John Kellogg popularised the idea that breakfast is the most important meal of the day to sell more of his cereal), then you’ll be employing gluconeogenesis longer.

But you’ve still got the glycogen stores in your skeletal muscle, even with prolonged fasting, unless you’ve already depleted them with previous intense and prolonged anaerobic exercise.  400 grams of glycogen represents a lot of energy, unless it’s anaerobic exercise, which is very inefficient.  I can’t be bothered checking the figures, but I seem to remember that with anaerobic exercise, one glucose molecule produces 2 molecules of ATP and lactate.  With aerobic exercise, one glucose molecule produces 36 molecules of ATP.

Intermittent fasting differs from low carbohydrate/high fat ketogenic diets in that (depending on which foods are actually being consumed with the intermittent fasting - it’s a strategy, not a diet), glycogen stores in skeletal muscle will be normal (if there’s enough carbohydrate in the diet), but with ketogenic diets glycogen stores in skeletal muscle will (or should be) low.

And unless very large amounts of dietary protein is consumed, with ketogenic diets, there will be appreciable consumption of skeletal muscle protein to supply glucose to the brain, until the brain adapts to using ketone bodies instead.

The skeletal muscles also contain significant stores of fat, in slow twitch fibres, involved in aerobic endurance exercise, which I prefer.  I’m more of a marathon runner than a sprinter.  I sometimes think about doing some weight training, but I just sit down until the thought has gone away.
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Offline CarbShark

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Re: Intermittent fasting. Health benefits?
« Reply #178 on: January 14, 2020, 04:22:24 PM »
Enough to sustain activity without having to catabolize healthy tissue, of course.

There are two ways to get protein from muscle and other lean tissue.

The first is from the normal every day breakdown of that tissue, and usually that protein is replaced with dietary protein for a net effect of zero.

When dietary protein is limited or unavailable, the source of that protein (lean tissue) is not replenished. For a negative net effect.

The second way to get protein from muscle and other lean tissue is to catabolize healthy tissue.

The body will do this if glucose is low and there is insufficient protein available to make glucose.

The targets for catabolization are mostly muscle, because most lean tissue is muscle, but also includes other organs. That does not exclude brain and heart tissue. In extreme cases that catabolization leads to death.

Again, if you are attempting to do resistance training, with low blood glucose (burning muscle glycogen, fat and ketones for energy), your body will start making as much glucose as it can.

After a single day of 23:1 intermittent fasting, you probably won't have much of an issue.

But if you string three or four of those days together in a row, and you're consuming a diet high enough in carbs to inhibit ketosis, and you're doing resistance training or other vigorous exercise, then you risk depleting healthy tissue.


The other more likely danger is that your body is not replenishing broken down muscle. That will leave you weaker, and is almost certain to happen (unless you're fat adapted in ketosis and on a LC diet) but isn't as dangerous as burning your own heart, brain and other lean tissue to fuel resistance training during a fast.
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Offline bachfiend

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Re: Intermittent fasting. Health benefits?
« Reply #179 on: January 14, 2020, 04:50:32 PM »
Enough to sustain activity without having to catabolize healthy tissue, of course.

There are two ways to get protein from muscle and other lean tissue.

The first is from the normal every day breakdown of that tissue, and usually that protein is replaced with dietary protein for a net effect of zero.

When dietary protein is limited or unavailable, the source of that protein (lean tissue) is not replenished. For a negative net effect.

The second way to get protein from muscle and other lean tissue is to catabolize healthy tissue.

The body will do this if glucose is low and there is insufficient protein available to make glucose.

The targets for catabolization are mostly muscle, because most lean tissue is muscle, but also includes other organs. That does not exclude brain and heart tissue. In extreme cases that catabolization leads to death.

Again, if you are attempting to do resistance training, with low blood glucose (burning muscle glycogen, fat and ketones for energy), your body will start making as much glucose as it can.

After a single day of 23:1 intermittent fasting, you probably won't have much of an issue.

But if you string three or four of those days together in a row, and you're consuming a diet high enough in carbs to inhibit ketosis, and you're doing resistance training or other vigorous exercise, then you risk depleting healthy tissue.


The other more likely danger is that your body is not replenishing broken down muscle. That will leave you weaker, and is almost certain to happen (unless you're fat adapted in ketosis and on a LC diet) but isn't as dangerous as burning your own heart, brain and other lean tissue to fuel resistance training during a fast.

This is all nonsense.

If you’re on a normal non-low carbohydrate/high fat ketogenic diet, then your skeletal muscle will contain around 400 grams of glycogen stores, mainly in the fast-twitch fibres used for short intense physical exercise.  Skeletal muscle also runs on its fat stores too.

Even if you manage to deplete your muscle glycogen stores at the end of a 23 hour fast, you will still be able to restore them if you’re on a normal diet with adequate carbohydrates.

You will have problems, though, if you’re on a very low carbohydrate diet and you’re deliberately reducing your supply of glucose and glycogen stores, both in the liver and also in skeletal muscle.  Then you’re going to be using increased muscle protein to make glucose via gluconeogenesis.

And you don’t consume sufficient dietary protein to prevent this happening, not even your diet contains 27.5% protein as a proportion of energy intake.
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