Too good to be true?Has to be
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Well, I don't personally believe there's any such thing as excess dietary fat unless you're eating a caloric surplus. (Well, unless you intend to eat a surplus ... then I guess it's still not excess.)Whew, thanks. That's a mouthful!
Doesn't quite square with the facile images in my mind's eye. Excess dietary fat? Ketones from protein (meaning that excess protein converting to glucose in fact does not defeat ketosis)? Aaaaaiiieeee!
And no, excess protein converting to glucose does not defeat ketosis in a hypocaloric state. This is why there is exists such a thing as a high-protein ketogenic diet.
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But if I were to tack on 500g of fat, this might defeat ketosis? This seems to undercut the "dietary fat and body lard are interchangeable" mantra. ?? Oy vay...
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Wait. You aren't saying the protein itself is being converted to ketones. You're saying the body needs energy to convert protein to glucose so it's using ketones as that energy source. This also suggests the body was making ketones prior to the NEED for the glucose in the first place. That doesn't mean the ketones are made from GNG. They were being made anyway. GNG is only taking place to supply the minimal basic glucose for the few areas of the brain that require it. There would be no need for the body to stop ketone production in that case because of the demand driven GNG process. It knows it's only making a small amount for a very specific purpose and is very temporary. The rest of the body still needs fueling so it makes sense that ketones and glucose CAN be doing their thang at the same time. But this is seriously small amounts of glucose you're talking about. The brain only requires about 120g a day and the fat adapted brain requires even less.
Edited for spelling failures as usual0 -
OK, let me explain this differently so we can hopefully all be clear on how gluconeogenesis results in the production of ketone bodies, as there appears to be some confusion and lack of understanding of the concept.
Sorry for the wall-of-text ... but biochemistry just doesn't always have a "Coles Notes" way tor explanations.
First as an FYI, in normal folks the liver always provides a constant production of ketone bodies. Not a lot, and it just happens. They are used quite effectively by extra-hepatic (ie: outside the liver) tissues such as the heart and skeletal muscle. The concentration is so low in most people that even when excreted in urine, they're undetectable by standard urine tests. I only mention this because most folks are unaware that's it's happening.
Ketone bodies are produced (in greater quantity than normal) by the liver (from fatty acids) during any of the following situations:- fasting/starvation,
- low-carb dieting,
- long bouts of intense exercise, and;
- uncontrolled/untreated Type1 diabetes.
When blood glucose is low (and the body wants it) and after liver glycogen is depleted, it is the intense gluconeogenesis process that happens during the above situations (when gluconeogenesis has been stimulated by low/absent insulin and high glucagon concentrations in the blood) that provides the glucose the body wants/needs, and in-turn that causes the ketone-body production. Here's how:
When glucose is low and glycogen stores depleted, for the synthesis of glucose to occur a different source of carbons is required. Glycerol released from adipose (fat) tissue during lipolysis ('fat-burning') provides some of the carbons, with the remaining carbons coming from the hydrolysis of lean-tissue / muscle proteins.
Quick biochemistry tutorial: All of our cells ultimately require a substance called ATP (Adenosine Triphosphate) for cellular-respiration (ie: life
). The citric-acid cycle (also called the Krebs cycle or TCA cycle) is a series of chemical reactions used to release energy through oxidation of a substance called acetyl-CoA (acetyl-Co-Enzyme A) into CO2 and ATP. This cycle starts with a 2-carbon acetyl group from acetyl-CoA getting together with a compound called oxaloacetate to form citrate.
However, gluconeogenesis itself results in depletion of oxaloacetate (because it's diverted from the citric-acid cycle in order to form glucose in this chemical process) which, in-turn, causes a rise in the levels of acetyl-CoA - which just happens to be the substrate for ketone body production. It's the resulting accumulation of acetyl-CoA that activates ketogenesis. So basically, while the liver is doing all this gluconeogenesis work, it's also creating ketones from that acetyl-CoA ... The ketone bodies and the newly-produced glucose are both released into the bloodstream together. As time goes on and we approach keto-adaptation/nutritional ketosis .. the brain utilizes more ketones and less glucose, and the heart uses ketones as well.
Before keto-adaptation occurs (with the acetyl-CoA unable to enter the citric-acid cycle as a result of depletion of oxaloacetate which is needed for gluconeogenesis) the rate of production of ketones exceeds their utilization, causing ketonemia (which just means excess ketones in the blood, basically). This will be followed by ketonuria (yes, excess ketones in urine) as the body works to get rid of them. Once we hit this state, that's when people can smell the acetoacetate and/or acetone in breath and urine.
Over time what happens for low-carb dieters (and those starving, alike) is that the body starts to utilize glucose less for ATP generation and relies more and more on converting fat into ketones, and then converting ketones into substrate for the citric-acid cycle. This is why our ketone breath and ketonuria eventually diminish or disappear.
Ultimately, even when keto-adapted we continue the process of gluconeogenesis - just on a smaller scale. We all know the brain needs a little to be synthesized - even with keto-adaptation. What most don't know is that the erythrocytes, kidney medulla and testes (in men, obviously) exclusively utilize glucose for ATP production.
BTW - fun fact ... as ATP is recycled hundreds of times ... over the course of a day each one of us actually uses roughly our own body-weight in ATP for cellular respiration.3 -
albertabeefy wrote: »OK, let me explain this differently so we can hopefully all be clear on how gluconeogenesis results in the production of ketone bodies, as there appears to be some confusion and lack of understanding of the concept.
Sorry for the wall-of-text ... but biochemistry just doesn't always have a "Coles Notes" way tor explanations.
First as an FYI, in normal folks the liver always provides a constant production of ketone bodies. Not a lot, and it just happens. They are used quite effectively by extra-hepatic (ie: outside the liver) tissues such as the heart and skeletal muscle. The concentration is so low in most people that even when excreted in urine, they're undetectable by standard urine tests. I only mention this because most folks are unaware that's it's happening.
Ketone bodies are produced (in greater quantity than normal) by the liver (from fatty acids) during any of the following situations:- fasting/starvation,
- low-carb dieting,
- long bouts of intense exercise, and;
- uncontrolled/untreated Type1 diabetes.
When blood glucose is low (and the body wants it) and after liver glycogen is depleted, it is the intense gluconeogenesis process that happens during the above situations (when gluconeogenesis has been stimulated by low/absent insulin and high glucagon concentrations in the blood) that provides the glucose the body wants/needs, and in-turn that causes the ketone-body production. Here's how:
When glucose is low and glycogen stores depleted, for the synthesis of glucose to occur a different source of carbons is required. Glycerol released from adipose (fat) tissue during lipolysis ('fat-burning') provides some of the carbons, with the remaining carbons coming from the hydrolysis of lean-tissue / muscle proteins.
Quick biochemistry tutorial: All of our cells ultimately require a substance called ATP (Adenosine Triphosphate) for cellular-respiration (ie: life). The citric-acid cycle (also called the Krebs cycle or TCA cycle) is a series of chemical reactions used to release energy through oxidation of a substance called acetyl-CoA (acetyl-Co-Enzyme A) into CO2 and ATP. This cycle starts with a 2-carbon acetyl group from acetyl-CoA getting together with a compound called oxaloacetate to form citrate.
However, gluconeogenesis itself results in depletion of oxaloacetate (because it's diverted from the citric-acid cycle in order to form glucose in this chemical process) which, in-turn, causes a rise in the levels of acetyl-CoA - which just happens to be the substrate for ketone body production. So basically, while the liver is doing all this work, it's also creating ketones from that acetyl-CoA ... The ketone bodies and the newly-produced glucose are both released into the bloodstream together. As time goes on and we approach keto-adaptation/nutritional ketosis .. the brain utilizes more ketones and less glucose, and the heart uses ketones as well.
Before keto-adaptation occurs (with the acetyl-CoA unable to enter the citric-acid cycle as a result of depletion of oxaloacetate which is needed for gluconeogenesis) the rate of production of ketones exceeds their utilization, causing ketonemia (which just means excess ketones in the blood, basically). This will be followed by ketonuria (yes, excess ketones in urine) as the body works to get rid of them. Once we hit this state, that's when people can smell the acetoacetate and/or acetone in breath and urine.
Over time what happens for low-carb dieters (and those starving, alike) is that the body starts to utilize glucose less for ATP generation and relies more and more on converting fat into ketones, and then converting ketones into substrate for the citric-acid cycle. This is why our ketone breath and ketonuria eventually diminish or disappear.
Ultimately, even when keto-adapted we continue the process of gluconeogenesis - just on a smaller scale. We all know the brain needs a little to be synthesized - even with keto-adaptation. What most don't know is that the erythrocytes, kidney medulla and testes (in men, obviously) exclusively utilize glucose for ATP production.
BTW - fun fact ... as ATP is recycled hundreds of times ... over the course of a day each one of us actually uses roughly our own body-weight in ATP for cellular respiration.
Thanks for taking the time to explain all this.
Where do we sign up for your class?1 -
Ok. Very detailed.
One more question. We've all heard how the presence of urine ketones is expected to decrease upon fat adaptation over time. But what reason might that not happen for some people? Why would some people, myself for example, continue showing large urine ketones pretty much all the time. I am pretty much carnivore... about 5g max carbs but only since April and I've been keto since May 2015.
But I constantly read that it reduces upon adaptation and mine hasn't. What would explain that?0 -
Sunny_Bunny_ wrote: »Ok. Very detailed.
One more question. We've all heard how the presence of urine ketones is expected to decrease upon fat adaptation over time. But what reason might that not happen for some people? Why would some people, myself for example, continue showing large urine ketones pretty much all the time. I am pretty much carnivore... about 5g max carbs but only since April and I've been keto since May 2015.
But I constantly read that it reduces upon adaptation and mine hasn't. What would explain that?
Excess protein being converted to glucose so you are not fully going into ketosis?0 -
First, it doesn't always decrease upon adaptation. It *usually* does, but everyone is slightly different.Sunny_Bunny_ wrote: »Ok. Very detailed.
One more question. We've all heard how the presence of urine ketones is expected to decrease upon fat adaptation over time. But what reason might that not happen for some people? Why would some people, myself for example, continue showing large urine ketones pretty much all the time. I am pretty much carnivore... about 5g max carbs but only since April and I've been keto since May 2015.
But I constantly read that it reduces upon adaptation and mine hasn't. What would explain that?
Second, ketostix are a notoriously unreliable measure of your level of ketosis - though considerably cheaper than a meter...
Third, you state you eat 5g maximum carbohydrate ... that's going to keep you in deeper ketosis than most.
And finally ... women usually show deeper ketone levels than men on a ketogenic diet.
Factor those all in, and it might certainly explain it.
There may be other physiological factors at work - but without a lot more information, I can't speak to those.
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Sunny_Bunny_ wrote: »Ok. Very detailed.
One more question. We've all heard how the presence of urine ketones is expected to decrease upon fat adaptation over time. But what reason might that not happen for some people? Why would some people, myself for example, continue showing large urine ketones pretty much all the time. I am pretty much carnivore... about 5g max carbs but only since April and I've been keto since May 2015.
But I constantly read that it reduces upon adaptation and mine hasn't. What would explain that?
Excess protein being converted to glucose so you are not fully going into ketosis?
You can't have excess ketones without being fully in ketosis. You're either in or out.albertabeefy wrote: »
First, it doesn't always decrease upon adaptation. It *usually* does, but everyone is slightly different.Sunny_Bunny_ wrote: »Ok. Very detailed.
One more question. We've all heard how the presence of urine ketones is expected to decrease upon fat adaptation over time. But what reason might that not happen for some people? Why would some people, myself for example, continue showing large urine ketones pretty much all the time. I am pretty much carnivore... about 5g max carbs but only since April and I've been keto since May 2015.
But I constantly read that it reduces upon adaptation and mine hasn't. What would explain that?
Second, ketostix are a notoriously unreliable measure of your level of ketosis - though considerably cheaper than a meter...
Third, you state you eat 5g maximum carbohydrate ... that's going to keep you in deeper ketosis than most.
And finally ... women usually show deeper ketone levels than men on a ketogenic diet.
Factor those all in, and it might certainly explain it.
There may be other physiological factors at work - but without a lot more information, I can't speak to those.
Yeah that's always the answer I get.
It's just so vague. I feel like there must either be something wrong with the idea that it decreases or there is some mechanism that makes it vary from person to person and for no reason other than I want to know... I want to know. Lol
I know urine strips are junk but that's usually more in regards to false negatives or registering lower ketones. I've never heard of them reflecting higher that is actually present. Unless at least moderately dehydrated, which I doubt. Anyway, I test blood occasionally too and am always running well into nutritional ketosis land. It's not a matter of doubting adaption or anything. I just find all the mechanisms interesting and this is one puzzle that no one seems to have an exact explanation for. You just read that they decrease as if that's just the way it works. My head can't let go of the "but what about when it doesn't work that way"? Lol
Can't leave well enough alone!
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@albertabeefy you are giving me flashbacks from my Registered Personal Trainer days over 25 yrs ago, lol.0
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canadjineh wrote: »@albertabeefy you are giving me flashbacks from my Registered Personal Trainer days over 25 yrs ago, lol.
I hope they're not traumatic. 1
