Fat Vs Sugar - Mitochondrial Oxidation, CO2, Krebs Cycle

north

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Studying cell respiration now due to what i think is low CO2 in my own case. I haven't officially studied biology so i am pretty new to this, only learned what i know since started reading Peats stuff.
I got a few questions, or would like some opinion, from you guys who study biology or know this better.

1.
According to this graphic, when looking at the first steps in the glycolysis, step 3 is fructose-6-phosphate, is this what Peat talks about, that fructose skips a step in the energy production chain?
https://en.wikipedia.org/wiki/Cellular_ ... ration.svg

2.
From https://en.wikipedia.org/wiki/Cellular_respiration :
"Biology textbooks often state that 38 ATP molecules can be made per oxidised glucose molecule during cellular respiration (2 from glycolysis, 2 from the Krebs cycle, and about 34 from the electron transport system).[2] However, this maximum yield is never quite reached due to losses (leaky membranes) as well as the cost of moving pyruvate and ADP into the mitochondrial matrix, and current estimates range around 29 to 30 ATP per glucose.[2]"

So, if "leaky membranes" cause a lower amount of ATP to be produced, we should likely get a better production of ATP just by avoiding PUFA? But, is it the same that it takes 4 years for tissues to get rid of pufa, as "cell membranes" have no incorporated pufa? Since Peat has a different view on "membranes", how do we view something like "PUFA in a cell membrane"?

3.
They talk about O2 is the main electron acceptor, and some species can use other molecules for this. Is this where cascara and methylene blue plays a role, acting as an electron acceptor in place of oxygen if there is lack of it? I think haidut posted something about methylene blue only working in cells with inhibited respiration, so that should make sense.

4.
Peat has said that Saturated fatty acids are a good fuel source, and this is something which i have found a bit confusing. But he also said sugar generates more CO2. He himself ate high fat before.

This is from a post related to this:
"On a per molecule basis, it becomes clear that Fats are a much better source of energy to make ATP than are glucose molecules. Fat molecules are arranged in triglycerides–fully reduced molecule with three fatty acid chains, each of which may contain 18 carbons. Thus a single triglyceride has the potential to drive (18/2)*3=27 rounds of the citric acid cycle—as compared to two per molecule of glucose."
https://giantshoulders.wordpress.com/20 ... lycolysis/

Here is from the wiki of beta-oxidation:

"Fatty acid catabolism consists of:
*Activation and membrane transport of free fatty acids by binding to coenzyme A.
*Oxidation of the beta carbon to a carbonyl group.
*Cleavage of two-carbon segments resulting in acetyl-CoA.
*Oxidation of acetyl-CoA to carbon dioxide in the citric acid cycle.
*Electron transfer from electron carriers to the electron transfer chain in oxidative phosphorylation."


"...the ATP yield of palmitate (C16, n = 8) is:
(8 - 1) * 14 + 10 - 2 = 106 ATP"


So apparently oxidation of fatty acids do generate CO2 as well.

----

This is confusing. Why is sugar better...
Or is it as simple as the only reason for his choice and recommendation is that not using fat is mainly because all fat have some amount of PUFA, and sugar is a way to avoid PUFA?
Im a noob regarding this so i cant make sense of all of this. Im pretty sure Peat has pretty clear reasons which i don't understand yet.
If we could get hydrogenated coconut oil, that would be really good i suppose, and Peat recently said he did find that now...

What are your opinions?
 

jyb

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High CO2, thyroid, metabolism, avoidance of hypoglycaemia...does seem not incompatible with oxidative saturated fat metabolism from what I have read or experienced. But Peat prefers to use mostly sugar to avoid accumulating pufa (you'll always have some in the fat). Another consideration is that he does not think that fructose or that high insulin/blood glucose is harmful (compared to what others think), so this favours more sugar rather than less.

I personally find sat fat essential to my health so I certainly don't avoid it, to the contrary.
 

nikotrope

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Oxidation of sugar produces CO2 *before* Krebs cycle.

Oxidation of sugar is metabolically efficient in many ways, including sparing oxygen consumption. It produces more carbon dioxide than oxidizing fat does, and carbon dioxide has many protective functions, including increasing Krebs cycle activity and inhibiting toxic damage to proteins. The glycation of proteins occurs under stress, when less carbon dioxide is being produced, and the proteins are normally protected by carbon dioxide.

But if one does not metabolize glucose correctly, less ATP and CO2 will be produced than when eating fat because Krebs cycle activity will decrease.
 

Parsifal

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Interesting post, I've already read that saturated fat would be better than sugar and that the tropical diet is 60% saturated fat?
 

Elie

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This is an area that puzzles me too and I have taken basic academic biochem classes. while a single glucose molecule produces two CO2 molecules before the the entry of Acetyl coA into the citric acid cycle, each acetyl coA that goes in from a fat molecule with 6 or more carbons would produce more CO2 than a molecule of glucose. So seems to me more CO2 is produced by Fat metabolism.
Peat says fat Beta oxidation requires more oxygen. One glucose molecule requires six. How many oxygen atoms are needed to oxidize a fatty acid with X number of carbons?
Maybe Hidut or anyone else want to respond?
 

ThunderSpank

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I enjoy a high sugar low fat diet vs low sugar high Saturated fat. I get bad heart palpitations when I don't get enough sugar and when on high saturated fat low sugar I get very anxious, but no energy, my ability to think and process things goes out the window, I can't sleep very well, and If I continue the high fat for more than about two weeks my interest in the opposite sex disappears. After a few months I start to feel very sick, physically and mentally. For me personally I will never go down the High Fat low Carb road again, but maybe others have had success with it? Also I smelled like road kill :lol:
 

michael94

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If we could get hydrogenated coconut oil, that would be really good i suppose, and Peat recently said he did find that now...

Is hydrogenated coconut oil good? First I've heard about that stuff


drk said:
post 108534 This is an area that puzzles me too and I have taken basic academic biochem classes. while a single glucose molecule produces two CO2 molecules before the the entry of Acetyl coA into the citric acid cycle, each acetyl coA that goes in from a fat molecule with 6 or more carbons would produce more CO2 than a molecule of glucose. So seems to me more CO2 is produced by Fat metabolism.
Peat says fat Beta oxidation requires more oxygen. One glucose molecule requires six. How many oxygen atoms are needed to oxidize a fatty acid with X number of carbons?
Maybe Hidut or anyone else want to respond?

yep very interesting topic
 
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BingDing

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This is from a post related to this:
"On a per molecule basis, it becomes clear that Fats are a much better source of energy to make ATP than are glucose molecules. Fat molecules are arranged in triglycerides–fully reduced molecule with three fatty acid chains, each of which may contain 18 carbons. Thus a single triglyceride has the potential to drive (18/2)*3=27 rounds of the citric acid cycle—as compared to two per molecule of glucose."

I remember reading this a long time ago, it is absurd IMO. Of course three large molecules have more potential energy than one small molecule. But that is like saying three SUVs weigh more than a motorcycle, BFD. Energy per carbon atom would be an interesting analysis, or some other normalized denominator.

My understanding, which could be quite wrong, is that once you get to pyruvate every thing after that is the same. And glucose -> pyruvate takes less energy than fat or protein -> pyruvate.

I share the OP's hope than an accurate and clear explanation shows up sometime.
 

Travis

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I just came across yet another name for the Krebs' Cycle: The Glyoxylate Cycle!

Now there are four names that I know of for this. Others are The Citric Acid Cycle and The Tricarboxylic Acid Cycle.

[Mitch Hedberg voice:] Why can't they just let Krebs have his cycle?
 
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Mito

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This is an area that puzzles me too and I have taken basic academic biochem classes. while a single glucose molecule produces two CO2 molecules before the the entry of Acetyl coA into the citric acid cycle, each acetyl coA that goes in from a fat molecule with 6 or more carbons would produce more CO2 than a molecule of glucose. So seems to me more CO2 is produced by Fat metabolism.
Carbohydrate oxidation generates 50% more carbon dioxide than fat oxidation.
Carbon Dioxide - Carbs Vs Fat Oxidation
 

Travis

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This is an area that puzzles me too and I have taken basic academic biochem classes. while a single glucose molecule produces two CO2 molecules before the the entry of Acetyl coA into the citric acid cycle, each acetyl coA that goes in from a fat molecule with 6 or more carbons would produce more CO2 than a molecule of glucose. So seems to me more CO2 is produced by Fat metabolism.
They both have the potential to produce the same amount of carbon dioxide per carbon. Every carbon that enters from either fat or sugar can be exhaled as carbon dioxide.

But on a per coenzyme A basis, carbohydrate generates more carbon dioxide because—like you said—three CO₂ are released per CoA instead of two CO2 with fatty acids. So if there is a finite amount of CoA—if it's a limiting factor—then carbohydrate metabolism should generate CO₂ at a faster rate, leading to higher CO₂ concentrations.

carbon dioxide.png

The Effect of High Fat and High Carbohydrate Diets on Rates of Weight Loss in Mice

...each acetyl coA that goes in from a fat molecule with 6 or more carbons would produce more CO2 than a molecule of glucose.
Each long-chain fatty acid molecule would almost certainly produce more carbon dioxide that one glucose molecule, but probably not on a per calorie basis (and certainly not within the same time period.)

More carbon is lost through other means on a high-fat diet. A high-fat diet upregulates bile salt production which are lost through the intestines. Also, more carbon is lost in urine as ketones. This is carbon that has lost its chance to ever become carbon dioxide within the body (...but probably will someday; somewhere...).

But it depends on the fatty acids too of course. The very short-chained fatty acids are probably on par with sucrose in terms of metabolic efficiency. Most fat-feeding studies use polyunsaturated fatty acids and long-chained saturated and monounsaturated fatty acids.

Solubility is an issue with fats. The extra modifications involved in transporting long-chained fatty acids would be bound to slow-down their metabolism a bit.
 
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Elie

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They both have the potential to produce the same amount of carbon dioxide per carbon. Every carbon that enters from either fat or sugar can be exhaled as carbon dioxide.

But on a per coenzyme A basis, carbohydrate generates more carbon dioxide because—like you said—three CO₂ are released per CoA instead of two CO2 with fatty acids. So if there is a finite amount of CoA—if it's a limiting factor—then carbohydrate metabolism should generate CO₂ at a faster rate, leading to higher CO₂ concentrations.

View attachment 5885
The Effect of High Fat and High Carbohydrate Diets on Rates of Weight Loss in Mice


Each long-chain fatty acid molecule would almost certainly produce more carbon dioxide that one glucose molecule, but probably not on a per calorie basis (and certainly not within the same time period.)

More carbon is lost through other means on a high-fat diet. A high-fat diet upregulates bile salt production which are lost through the intestines. Also, more carbon is lost in urine as ketones. This is carbon that has lost its chance to ever become carbon dioxide within the body (...but probably will someday; somewhere...).

But it depends on the fatty acids too of course. The very short-chained fatty acids are probably on par with sucrose in terms of metabolic efficiency. Most fat-feeding studies use polyunsaturated fatty acids and long-chained saturated and monounsaturated fatty acids.

Solubility is an issue with fats. The extra modifications involved in transporting long-chained fatty acids would be bound to slow-down their metabolism a bit.
They both have the potential to produce the same amount of carbon dioxide per carbon. Every carbon that enters from either fat or sugar can be exhaled as carbon dioxide.

But on a per coenzyme A basis, carbohydrate generates more carbon dioxide because—like you said—three CO₂ are released per CoA instead of two CO2 with fatty acids. So if there is a finite amount of CoA—if it's a limiting factor—then carbohydrate metabolism should generate CO₂ at a faster rate, leading to higher CO₂ concentrations.

View attachment 5885
The Effect of High Fat and High Carbohydrate Diets on Rates of Weight Loss in Mice


Each long-chain fatty acid molecule would almost certainly produce more carbon dioxide that one glucose molecule, but probably not on a per calorie basis (and certainly not within the same time period.)

More carbon is lost through other means on a high-fat diet. A high-fat diet upregulates bile salt production which are lost through the intestines. Also, more carbon is lost in urine as ketones. This is carbon that has lost its chance to ever become carbon dioxide within the body (...but probably will someday; somewhere...).

But it depends on the fatty acids too of course. The very short-chained fatty acids are probably on par with sucrose in terms of metabolic efficiency. Most fat-feeding studies use polyunsaturated fatty acids and long-chained saturated and monounsaturated fatty acids.

Solubility is an issue with fats. The extra modifications involved in transporting long-chained fatty acids would be bound to slow-down their metabolism a bit.
Great info Mito and Travis. Thank you.
 

DuggaDugga

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They both have the potential to produce the same amount of carbon dioxide per carbon. Every carbon that enters from either fat or sugar can be exhaled as carbon dioxide.

But on a per coenzyme A basis, carbohydrate generates more carbon dioxide because—like you said—three CO₂ are released per CoA instead of two CO2 with fatty acids. So if there is a finite amount of CoA—if it's a limiting factor—then carbohydrate metabolism should generate CO₂ at a faster rate, leading to higher CO₂ concentrations.

View attachment 5885
The Effect of High Fat and High Carbohydrate Diets on Rates of Weight Loss in Mice


Each long-chain fatty acid molecule would almost certainly produce more carbon dioxide that one glucose molecule, but probably not on a per calorie basis (and certainly not within the same time period.)

More carbon is lost through other means on a high-fat diet. A high-fat diet upregulates bile salt production which are lost through the intestines. Also, more carbon is lost in urine as ketones. This is carbon that has lost its chance to ever become carbon dioxide within the body (...but probably will someday; somewhere...).

But it depends on the fatty acids too of course. The very short-chained fatty acids are probably on par with sucrose in terms of metabolic efficiency. Most fat-feeding studies use polyunsaturated fatty acids and long-chained saturated and monounsaturated fatty acids.

Solubility is an issue with fats. The extra modifications involved in transporting long-chained fatty acids would be bound to slow-down their metabolism a bit.

Carbohydrates provide the pyruvate for oxaloacetate, which initiates the TCA cycle. This can still occur on a no-carb diet due to gluconeogensis, but it's inefficient and has requires additional metabolizing and excretion of by-products. Not ideal given you can just consume carbohydrates directly.

"Fats burn in the flame of carbohydrate".

Low carb/no carb dieting is almost untenable barring, perhaps, some extreme situations.
 

LucH

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This is confusing. Why is sugar better...

What are your opinions?
We need carbon dioxide (CO2) in what is called “Respiratory compensation”. When we burn glucose or fats, we don’t release as much carbonic acid (H2CO3) as needed. We have to compensate. And there is more compensation needed with fats than with carbs. HCO3 (bicarbonate) is there to act as buffer. H+ is then freed. If too much Hydrogen is present, pH blood lowers and it must be compensated.

Excerpt from a video by Chris Masterjohn
When we burn glucose or fats, we don’t release as much carboxilic acid as needed. Fat has a quarter of oxygen it needs.
We release more CO2 when we metabolize carbs, and some water (H2O).
For fats, we need more water to metabolize and we won’t release as much CO2.
https://youtu.be/2Hm09jg_DIs
upload_2017-7-31_23-23-26.gif
(Carbs, fats and carbon dioxide)
Fats-11.-Breathing-control-acidity.-Compensation-mecanism-50-%.png

See too:
Role of carbon dioxide
From Ray PEAT Ph.Dr. Protective CO2 and aging
http://raypeat.com/articles/articles/co2.shtml
 

Travis

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Carbohydrates provide the pyruvate for oxaloacetate, which initiates the TCA cycle. This can still occur on a no-carb diet due to gluconeogensis, but it's inefficient and has requires additional metabolizing and excretion of by-products. Not ideal given you can just consume carbohydrates directly.
I didn't think that you needed pyruvate for the TCA cycle. The full cycle is sometimes drawn with pyruvate (from glycolysis), but I consider acetyl-CoA as the "start." This can be formed either from pyruvate (glycolysis) or the β-oxidation of fatty acids.

I was under the impression that fatty-acid-derived acetyl-CoA molecules could enter the TCA cycle without becoming glucose again, with the exception of the brain (where glucose is irreplaceable). I certainly agree that metabolizing glucose is more efficient than metabolizing fats (unless you're a backpacker and have to worry about the caloric density of the food you carry.)
 

DuggaDugga

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I didn't think that you needed pyruvate for the TCA cycle. The full cycle is sometimes drawn with pyruvate (from glycolysis), but I consider acetyl-CoA as the "start." This can be formed either from pyruvate (glycolysis) or the β-oxidation of fatty acids.

I was under the impression that fatty-acid-derived acetyl-CoA molecules could enter the TCA cycle without becoming glucose again, with the exception of the brain (where glucose is irreplaceable). I certainly agree that metabolizing glucose is more efficient than metabolizing fats (unless you're a backpacker and have to worry about the caloric density of the food you carry.)
https://chrismasterjohnphd.com/2016/07/28/ketogenesis-isnt-all-about-carbs-and-insulin/
Around twelve minutes Chris starts discussing it.
 

Travis

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Carbohydrates provide the pyruvate for oxaloacetate...
Oh. I'm sorry. I read that sentence⇑ as "carbohydrates provide pyruvate to add to oxalaoacetate (citrate synthesase)" and not as "carbohydrates provide the pyruvate to synthesize oxaloacetate (pyruvate carboxylase)" as you had intended.

I hope you can see how the meaning of that sentence can be understood both ways.
 

kateb

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Sugar is preferred fuel by body and needed for brain especially hence gluconeogenesis. I sort of have the opposite question to original post: What I don't understand is that is sugar and fat compete in krebe cycle why is more than a minimum amount of coconut oil recommended. I know we need some fat but if glucose is stimulating o2 production and is our best primary fuel source why interfere with its metabolism by adding a lot of extra fat (more than say 10%) of calories?
 

tara

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What I don't understand is that is sugar and fat compete in krebe cycle why is more than a minimum amount of coconut oil recommended.
Peat only recommends small amounts added to meals, eg ~1tsp.
Personally, I sometimes go for more if I want a more suitable fat to prepare a particular food - eg for baking potato chips or to mix with butter when baking something etc. Otherwise I don't know why others recommend much more either.
 

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