Beta Oxidation Vs Glycolysis

kranum

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It seems pointless to think about the amount of energy in one molecule of palmitic acid compared to one molecule of glucose, and then conclude that beta oxidation produces more energy. Unless you measure your food intake in moles of glucose or fat that is. But this difference is the reason why fat is more calorie dense, so if you eat the same number of calories of glucose and fat I wouldn't expect a significant difference in energy production. Here, on the other hand, there would be a difference in CO2 production, due to the decarboxylation of pyruvate, so i think this is why burning glucose would be preferred.
 
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I've heard Ray mention that fat burning produces a lot more free radicals. If anyone has a source that backs this up, please share!... especially because most of the modern propoganda is claiming that burning fat is cleaner. I think Ray has also mentioned that uncoupled mitochondria produce the least free radicals, and the most CO2.
 

Pointless

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Well if atp is more important than co2, Dr. Peat wouldn't be talking about mitochondrial uncouplers which burn more glucose for less atp to create more co2 and other benefits.
 
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Peatit

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Is that possible that the more ATP that occur with the beta oxidation pathway result from a shift in energy resources (beta-oxidation is dependant from lipases that are activated by epinephrine, norepinephrine, glucagon and cortisol, often described as catabolic hormones ) to provide more energy for brain and muscles in a situation that the organism may falsy interpret like a stressful one? much like the one that can be seen in the fight or flight response?
Hence, like in a sustained response to stressful and traumatic events ( endogenous and/or exogenous), the major goal here is to provide more energy and then more ATP. But a transient decline in immunity could be one cost of this energetic shift.
If that the case, only people with good liver, kidneys and hormonal/mental status could sustain on this metabolic pathway, what do you think?
I was more thinking of dietary fats fate, all things being equal , compared with glucose.
I am pretty sure like you seem to be that beta oxidation of fats being released endogenously because of stress hormones would have detrimental consequences in the long (or even short) term. But can't dietary fats reach the general blood circulation without being stored beforehand?
I think you made extensive research on the topic of fat digestion and brought very good points in others threads I read, I'm sure you're very knowledgeable on this.
 
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Peatit

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I even thought lately that the increased ATP production in the beta oxidation could explain that fats are prioritized in the Randle cycle:
Doesn't RP himself explain that SFAs are oxidized preferably when available at the same time as PUFAs (those are stored instead)? If we extrapolate from this that our cells oxidize the most energetic substrate first, it would also make sense that FAs are oxidized first even in presence of the "inferior" glucose as Randle noticed.

The problem being that this cycle was "evolutionary designed" in a PUFAs free world and it becomes maladaptive when the FAs are unsaturated.
For our ancestors it wasn't a big deal, because most of their dietary fats were saturated, and even if their few dietary PUFAs accumulated, it wasn't significant given their short lifespan.

Of course I am speculating again!
 

jyb

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I was more thinking of dietary fats fate, all things being equal , compared with glucose.
I am pretty sure like you seem to be that beta oxidation of fats being released endogenously because of stress hormones would have detrimental consequences in the long (or even short) term. But can't dietary fats reach the general blood circulation without being stored beforehand?
I think you made extensive research on the topic of fat digestion and brought very good points in others threads I read, I'm sure you're very knowledgeable on this.

Fat release during high stress is not too surprising: you need it to survive, otherwise you die very quickly if you just had glucose running out. However, that itself does not prove that beta oxidation is stressful, in my opinion it is a massive confusion of cause and effect. Just because fatty acids are finally released during stress does not mean that regular beta oxidation under normal circumstances will create stress. Beta oxidation is killed by conventional diets, but otherwise it seems to me like normal... I usually seek it.
 
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Wilfrid

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I was more thinking of dietary fats fate, all things being equal , compared with glucose.
I am pretty sure like you seem to be that beta oxidation of fats being released endogenously because of stress hormones would have detrimental consequences in the long (or even short) term. But can't dietary fats reach the general blood circulation without being stored beforehand?
I think you made extensive research on the topic of fat digestion and brought very good points in others threads I read, I'm sure you're very knowledgeable on this.
You raised very important remarks about beta-oxidation. I'm not sure about my theory too.
To tell the truth, your post like also few other insightful quotes made by canstopeating, jyb etc.... has made me realize that the answer to this problem is far more complex than just oxydizing fats=bad and oxydizing any -ose= good.
Lately, I 've been reading some few interesting studies about photoperiodism and how day light can affect mammals digestive capacities...for example, exposure to short days decreases relative abundance of proteobacteria, which are most efficient at harvesting energy from high fat foods. So it seems legit to think that at a certain period of the year, the body thrives on oxydizing fat rather than sugar and vice-versa. It's a well-known fact that photoperiodism can affect thyroid, sexual and a lot of more endogenous hormones secretion. After all, insulin and glucagon are both hormones too.
So even the location of the individual on the globle seems to have a huge influence on the oxydative process and the needed appropriate " fuel " to support an efficient basal metabolic rate.
Plus, Ray himself spoke favorably about glucagon in few of his email response.
 
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ATP

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But can't dietary fats reach the general blood circulation without being stored beforehand?
Did you find an answer to this? I am interested in finding this out. It could be possible to be burning fat without the stress response.
 

Elron

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Maybe skinny people do well with high carb because they can't handle the atp substrated from oxidation of fats. And perhaps musuclar people do well with higher fatty diets is due to overrall better nutritional status (besides when confounded), and that muscles burn fats preferentially (not sure why).
 
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Peatit

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Did you find an answer to this? I am interested in finding this out. It could be possible to be burning fat without the stress response.
Not sure yet, I haven't looked deeper on the matter but I think it's possible through chylomicrons. So dietary fats could then reach tissues without the need for stress hormones to rise.
 

ATP

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Not sure yet, I haven't looked deeper on the matter but I think it's possible through chylomicrons. So dietary fats could then reach tissues without the need for stress hormones to rise.
If one were to keep glycogen stores full whilst allowing beta oxidation to produce the ATP, it could be possible to keep the stress response at bay.
 

Mito

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But can't dietary fats reach the general blood circulation without being stored beforehand?
Did you find an answer to this? I am interested in finding this out. It could be possible to be burning fat without the stress response.
MCT's (8 and 10-carbon fatty acids, or fatty acids that are even shorter) go directly from the intestine into the liver via the portal vein. Fatty acids that are 10 or fewer carbons make their way into the mitochondrion and are burned for energy.
 
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Did you mean fatty acids that are 10 or greater? I've known coconut oil can be oxidized without being stored, and I knew LCFA's were oxidized in the mitochondria. Never considered what happens to SCFA's, say the ones produced by gut flora, like butyrate, acetate, propionate.
 

Mito

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Did you mean fatty acids that are 10 or greater?
All fat (that is not stored) is beta-oxidized in the mitochondria. C10 and shorter fatty acids can pass through the mitochondrial membrane without needing to use the "Carnitine Shuttle" (thus they can be oxidized faster than LCFA's).

IMG_0772.jpg
 

yerrag

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Ray Peat talks about fatty acid oxidation producing more lactic acid. Has there been an explanation ever been made as to why this is so?

There's less CO2 produced by FAO, but does it necessarily imply that more lactic acid is produced?
 

Mito

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Ray Peat talks about fatty acid oxidation producing more lactic acid. Has there been an explanation ever been made as to why this is so?

There's less CO2 produced by FAO, but does it necessarily imply that more lactic acid is produced?
“The inhibitory effect of FAO on glucose oxidation is much more profound than that on glycolysis and may lead to a discordant metabolism of glucose through glycolysis with the potential to induce acidosis (Figure 8.17).”
Randle Cycle - an overview | ScienceDirect Topics
 

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Thanks, that was very helpful!
 

yerrag

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I should try to rephrase what the article is saying for a lay person: Fatty acid oxidation would compete with oxidative metabolism (where glucose is used instead of fats) such that the metabolism of glucose would not involve all of the glucose substrate being used towards oxidative metabolism, with some of it completed at the glycolytic level, where lactic acid is produced.

I guess that this is a matter of degree: The more metabolism is dependent on fatty acid oxidation, the more lactic acid is produced from the metabolism of sugar, concurrently running with fatty acid oxidation.

One would then ask what if the body if running on 100% fatty acid oxidation. Is this possible? I think there is no such thing, as the body would simply turn protein to sugar in the absence of sugar consumption. Am I right here?
 

Mito

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One would then ask what if the body if running on 100% fatty acid oxidation. Is this possible? I think there is no such thing, as the body would simply turn protein to sugar in the absence of sugar consumption. Am I right here?
According to Masterjohn there will still be a minimum of 50 or 60 grams of glucose needed even if there are enough keytones around. The glucose can come from gluconeogenesis as you suggested.

“Your brain will consume 120 grams of carbohydrate every day. There's got to be another 30 grams or so that would be used no matter what obligately by red blood cells, certain cells in the testes, the kidney, and the lens of the eye. Then the rest of your body — if you're eating not a ketogenic diet, the rest of your body is not really trying to burn fat, so it's going to burn through carbohydrate.

Your liver stores about 90 grams of carbohydrate to be able to stabilize your blood sugar between meals, and overnight fasting is the time where it has to do that.

If you add that up, you're looking at like 250 grams of carbohydrate a day — and remember we haven't gotten to high-intensity exercise yet.

Now, if you go on a ketogenic diet, what happens?

Well, your brain glucose consumption goes down from 120 grams a day to like 30 or 35 grams a day. You cannot and will not ever, ever, ever, ever, ever go to zero. That's one thing. You still have another 20-30 grams of carbohydrate that you're burning through by cells that cannot burn anything else. You still have a minimum probably 60 or 70 grams of carbs per day that you need — even when you're maximally keto-adapted. I'm not saying you need to eat those carbs. You'll make them through gluconeogenesis if you don't eat them.

But the rest of the body where the needs were flexible, has mostly shifted to burning fat for fuel on a long-term ketogenic diet. So, the real big problem is if you're not low-carb enough to be keto, but you're way under 200, 250 grams of carbs a day. Like, probably 100 grams of carbs a day, if it works for you, great — but if you have symptoms of low blood sugar at night, you shouldn't be spending a lot of time guessing why, because you're in this gray area where you are not keto-adapted, your brain is still burning through 120 grams a day, your liver still stores 90 grams a day, and the rest of your body still probably is preferentially burning carbs for energy instead of storing them for the most part because the carbs are there. So, your body is not deliberately, intensively reorganizing to conserve the carbohydrate in that gray area.

==If you are eating 50 or 100 grams of carbs, and you are in this place, then you absolutely should connect the two and see if increasing your carbs helps.

Low-carb is not the best solution to high fasting glucose. There's a lot of people on low-carb who have high fasting glucose. There's a ton of people who go low-carb and develop high fasting glucose. That’s because a low carb diet alters the hormonal environment in two main ways:

⭐️1.) Increases the morning glucagon response.

⭐️2.) Increases adrenal hormones.

Both of these are early and late-stage adaptations to low glucose supply.”

Ask Me Anything About Nutrition!
 

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