Trying to Understand Peat's View of Fat Burning

This article by Peat:

http://raypeat.com/articles/articles/co2.shtml

contains this passage:

"In eccentric exercise and denervation, less oxygen is used and less carbon dioxide is produced, while lactic acid increases, displacing carbon dioxide, and more fat is oxidized. Prolonged stress similarly decreases carbon dioxide and increases lactate, while increasing the use of fat."

I certainly understand the idea that some kinds of exercise favor anaerobic glycolysis, and yes that creates lactic acid instead of CO2. But why would he believe that anaerobic glycolysis oxidizes more fat? Why would fat burning create lactic acid instead of CO2?

When we are at rest or low levels of exertion, are we always in anaerobic metabolism, or is this also krebs cycle? How much of this activity gets fuel from fat instead of glucose?

I thought that sustained periods of aerobic metabolism at some point switch from glucose to fat burning? What aerobic metabolism cycle is involved in such fat burning as part of aerobic metabolism? Does that process not have CO2 as the output?

Assuming that the fat burning in aerobic metabolism is "oxidative phosphorylation" this article from Wikipedia seems to support my line of questioning:

http://en.wikipedia.org/wiki/Oxidative_phosphorylation

Quoted section:
"The amount of energy released by oxidative phosphorylation is high, compared with the amount produced by anaerobic fermentation. Glycolysis produces only 2 ATP molecules, but somewhere between 30 and 36 ATPs are produced by the oxidative phosphorylation of the 10 NADH and 2 succinate molecules made by converting one molecule of glucose to carbon dioxide and water,[4] while each cycle of beta oxidation of a fatty acid yields about 14 ATPs. "

I cnnfess to hasty reading here.
A good starting point involves glucuronidation

http://en.wikipedia.org/wiki/Glucuronidation

narouz said:

I cnnfess to hasty reading here.
A good starting point involves glucuronidation

http://en.wikipedia.org/wiki/Glucuronidation

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I don't think that has anything to do with fat burning inside of aerobic metabolism.

pone said:

This article by Peat:

http://raypeat.com/articles/articles/co2.shtml

contains this passage:

"In eccentric exercise and denervation, less oxygen is used and less carbon dioxide is produced, while lactic acid increases, displacing carbon dioxide, and more fat is oxidized. Prolonged stress similarly decreases carbon dioxide and increases lactate, while increasing the use of fat."

I certainly understand the idea that some kinds of exercise favor anaerobic glycolysis, and yes that creates lactic acid instead of CO2. But why would he believe that anaerobic glycolysis oxidizes more fat? Why would fat burning create lactic acid instead of CO2?

Click to expand...

In my understanding, exercise, anaerobic glycolysis and lactate can all increase stress, and increased stress promotes the burning of more fat. If there's a lot of stored PUFAs in the system then those will overwhelm the liver's ability to detoxify (via Glucuronidation) them and cause other negative effects.

When we are at rest or low levels of exertion, are we always in anaerobic metabolism, or is this also krebs cycle? How much of this activity gets fuel from fat instead of glucose?

Click to expand...

The metabolism will be most aerobic when you're in a low stress state in my understanding.

I thought that sustained periods of aerobic metabolism at some point switch from glucose to fat burning? What aerobic metabolism cycle is involved in such fat burning as part of aerobic metabolism? Does that process not have CO2 as the output?

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I suppose you're referring to "aerobic" exercise.

"Dr. Ray Peat: I'm not sure who introduced the term "aerobic" to describe the state of anaerobic metabolism that develops during stressful exercise, but it has had many harmful repercussions. In experiments, T3 production is stopped very quickly by even "sub-aerobic" exercise, probably because of the combination of a decrease of blood glucose and an increase in free fatty acids. "

However, I think proper burning of saturated fats is comparatively ok, I'm not completely clear on the details here. PUFAs on the other hand can poison the mitochondria, so elevated unsaturated FFAs can cause damage. So the effect of exercise is dependent on the fats stored in your body.

So let's talk about "Aerobic Exercise". Anaerobic glycolysis feeds the Krebs Cycle, which releases CO2. Krebs Cycle feeds the electron transport chain, which fully oxidizes energy from glucose.

Let's forget PUFAs; that is a side topic. Focus on saturated fat stored in your tissues. At some point during aerobic exercise, aren't you supposed to start burning saturated fat instead of glucose? And if yes, is this any less efficient than burning glucose? Because there are a ton of low carb - and ketogenic diet - web sites claiming that fat burning inside of aerobic energy metabolism and exercise is as - or more - efficient than burning glucose.

I have problems understanding Peat, because he seems to imply that you only burn fat in an anaerobic mode, and that cannot be right.

pone said:

So let's talk about "Aerobic Exercise". Anaerobic glycolysis feeds the Krebs Cycle, which releases CO2. Krebs Cycle feeds the electron transport chain, which fully oxidizes energy from glucose.

Let's forget PUFAs; that is a side topic. Focus on saturated fat stored in your tissues. At some point during aerobic exercise, aren't you supposed to start burning saturated fat instead of glucose? And if yes, is this any less efficient than burning glucose? Because there are a ton of low carb - and ketogenic diet - web sites claiming that fat burning inside of aerobic energy metabolism and exercise is as - or more - efficient than burning glucose.

I have problems understanding Peat, because he seems to imply that you only burn fat in an anaerobic mode, and that cannot be right.

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We have to look at the context of burning fat. Exercise causes an increase in stress(cortisol, etc) which in turn increases lipolysis and fatty acids in the blood. The fatty acids lead to insulin resistance in muscles to spare glucose for tissues like the brain.

The rise in stress also leads to an increase in anaerobic glycolysis and blood lactate. The lactate is used to produce glucose for the brain, and when the lactate in the blood increases beyond the ability of the liver to process it, we hit the lactate or anaerobic threshold.

The increased fatty acids also promote fat burning, and this would be ok if the stored fats were mostly saturated.

So the fat burning may be aerobic by itself, but anaerobic metabolism is generally high when fat is being burned, and the rise in stress and lactic acid is still problematic.

Same thing with a low carb/ketogenic diet. Ketones in and of themselves can be beneficial, but the context of making them is stressful. There is some glucose requirement even in a low carb diet, and the process of making it is stressful(glucagon/cortisol). Keeping that stress up constantly isn't such a great thing long term.

This is my understanding.

Why would fat burning create lactic acid instead of CO2.

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Yes has to do with context. When you rely on fat burning, cortisol and epineprhine are released and (along with other hormones) increase free fatty acids (and glucose). Low blood sugar is a sign of major stress.

Oxidation of fatty acids and the release of fattys acid lead to differences in metabolic concentrations (ratio [acetyl coa]:[coa] and [nadh]:[nad+]). Both concentration differences and free fatty acids inhibit several enzymes, for example pyruvate dehydrogenase complex. (See also beta oxidation and pyruvate dehydroganse kinase).
Increasd pyruvate concentrations and lead to increased lactid acid concentrations (because of lactate dehydrogenase ; enzymes work in 2 ways depending of the concentrations). Derailing the efficient use of glucose even more, by lowering CO2 and altering the intra-cellular and extra-cellular environment. So prolonged exposure to stress or free fatty acids will limit efficient the oxidation of glucose and promote fat oxidation.

Note: Fatty acid oxidation along with sufficient glucose intake, inhibits free fatty acid release and concentration differences in metabolites. In most cases there's no reason to be scared to eat (saturated) fats however. It would even harm you if you wouldn't eat them, but just don't over do (50-100 gram is sufficient) and don't severely limit carbs.

http://www.functionalps.com/blog/. There's some interesting reads on functional alps.

Google also has some articles, for example http://ajpendo.physiology.org/content/297/3/E578.

Edit: added some more clarification to the initial question.

Your doubts are not clear to me. Fat is always entering the cell in some amount.

Your doubts are not clear to me. Fat is always entering the cell in some amount.

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If that's to what I wrote before. It's hard to give personal advice. As said it's all matter of context and personal state and the goal someone has in mind.
The 'some amount' is true but depends on concentrations. Sometimes if you want to change things, a change in concentration is needed to induce changes. Also if you can't oxidize this will alter your concentrations compared to other peoples hence need less for the same concentrations..

Suikerbuik said:

Your doubts are not clear to me. Fat is always entering the cell in some amount.

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If that's to what I wrote before. It's hard to give personal advice. As said it's all matter of context and personal state and the goal someone has in mind.
The 'some amount' is true but depends on concentrations. Sometimes if you want to change things, a change in concentration is needed to induce changes. Also if you can't oxidize this will alter your concentrations compared to other peoples hence need less for the same concentrations..

Click to expand...

Pone's question is not clear, I don't understand.

Yeah me neither to be honest. But can understand someone questioning why wouldn't we prefer fat over sugar?

However, these aren't separate things and it's not one or the other. Nor is Peat about blocking the beta oxidation. It's just about improving oxidative phosphorylation and limiting stress hormones, so krebs cyclus will move on and our glycolysis won't be hindered. The latter is very important for utilizing glucose to beneficial substances and wide range of effects. The increased CO2 per ATP for example, is really important for protein structure and pH.

All in all Peat is about favoring efficient energy production from glucose as seen in health and in low stress state.

Note: extracellular glucose is a poison actually. Which doesn't mean we should avoid glucose as being proposed by some people... No, that's just walking away our problems. Nor those people really understand the Krebs cyclus in my opinion and/ or the Warburg effect.

Suikerbuik said:

Note: extracellular glucose is a poison actually.

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Hmm, care to elaborate?

Sure, as you know every substance is a posion, so once again it's about balance. Too low bloodsugar will kill you and too much will get you all kinds of health issues.

Glucose should be rapidly cleared from the blood, phosphorylated (trapped by the cells now) and turned into glycogen or metabolized in the glycolysis - followed by kerbs cyclus and ETC, or turned into fatty acids.

Excess glucose in the bloodstream leads to glycosilation, high osmotic pressure, insulin release with all kind of effects, and other things. Therefore glucose clearance is important. However, by training our bodies to deal with glucose our glucose clearance get's better. When we avoid glucose or sugar we (likely) become less able to deal with glucose and when avoiding glucose for prolonged periods of time and going very low in carbs. We possibly even induce impaired glucose tolerance (pre-diabteic state).

So no worries, avoiding glucose is like I said just walking away from the problem. Though we want an as good as possible glucose clearance for sure.

Ray Peat has said that all common diabetes symptoms (besides the causes) are ascribable to excess insulin.

And extra cellular glucose is major in increasing insulin. However I don't dare to say that all effects are only mediated by insulin. I know that insulin certainly has a role in many pathological states no doubt about that. But I think glucose also induces changes above the physiological concentration:

http://www.ncbi.nlm.nih.gov/pubmed/11784718
In summary, we used SSH to identify 200 mesangial cell genes whose expression is enhanced or suppressed in response to high extracellular glucose. (from full text)
http://www.ncbi.nlm.nih.gov/pubmed/23051786
We identified 56 proteins that showed significant changes in protein expression, and 33 proteins showing significant changes in thiol reactivity, in response to high glucose concentration.

I wonder if the outside of the cell is trying to burn the sugar?

Such_Saturation said:

Ray Peat has said that all common diabetes symptoms (besides the causes) are ascribable to excess insulin.

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Where did he say that? Not my impression from what I have read.

its true higher than normal sugar in the blood can be a problem, increase osmotic pressure, however...almost everyone can rapidy clear sugar somehow, even if its becoming thirsty and peeing it out...which is diabetes. You have to be very mineral deficient and low in vitality for that to ever happen. I don't recommend eating all plain white sugar, you need vits and mins, but its actually very rare that sugar itself can ever cause problems or lead to weight gain...its hard to comprehend, it took me a while to realize it...it really is that simple and good. To me sucrose is the best form of sugar because even fruit usually has some indigestibles or sugar alcohols, polysacchardies, starches have the fermentables and fibers...sugar is the purest. Don't mean to deviate from the topic...

my impression is that if possible its best for all cells to utilize glucose, its the most efficient, but due to the high oxygen demand and relatively constant need to replenish, in most cases, sugar isn't always burned, or cant be. Palmitic acid (16c saturated fat) is the second most efficient fuel source, which is the type our body produces from excess glucose or other forms of energy besides longer chain fatty acids, which remain as is. Sometimes our body creates oleic acid (c18 mono unsaturated) or stearic acid (c18 saturated fatty acid) for more lubrication, structural, hormonal and other reasons other than for fuel, but can be easily liberated within the body and used if necessary, however they require a few more steps to be oxidized than palmitic acid or sugar, so therefore probably to a small degree but significantly slow metabolism and thyroid. Palmitic acid probably could be considered a neutral metabolism, whereas sugar is optimal and is usually what is required for quick healing, adaptation, action, inspiration, ability to sweat, become hot, stuff like that. As far as PUFAs go, our body can synthesize Mead acid which is a 20c monounsaturated fat but acts in the same pathways as PUFA. Peat thinks this is a better acid, the so called Mead's acid, than PUFAs because like oleic of stearic acid, it doesn't slow or 'poison' as Peat says metabolism very much or if at all...its of course not as fast as sugar, and probably not as fast as palmitic. Dietary PUFA like omega 3 and 6 fatty acids are apparently unnecessary and if the body is burdened enough to need to burn them as fuel, it significantly slows metabolism and thyroid function, to the extent it can actually weaken and injure cells and the body. In a hot metabolic state with plenty of sugar, these fatty acids can be attatched to glucuronic acid and urinated out or in some other way dealt with in an approptiate way. At this point personally I can attest to this...PUFA from the diet if at all necessary is very little to none, and definatly not what is mainstream recommended. Stearic and oleic acids (longer chain saturated and monounsaturated) seems half decent in the diet, like from cocoa fat for example, but don't give a feeling of abundant well being or seem to really even be that digested or absorbed that well. I view them as more of a structural need type fat that if fully grown and healthy probably doesn't need to be replenished that often, and for metabolism is concerned its just not that efficient digestively or metabolically...at best it might be good for cholesterol or hormone synthesis. Palmitic acid like from palm oil and dairy is nice to stay grounded and prevent to big of swings between sugar intakes, seems moderately beneficial for metabolism mostly just from a calorie stand point and probably hormone synthesis, and seems to digest efficiently, not 100% but pretty good. I cant ever hit prime feelings, sensations, really nice in my head thoughts, more of a feeling to give out good vibes, without a good amount of sugar throughout the day at least in 4 sittings but its even better if spread out throughout the day, pretty much perfect digestivly and noticeably more energizing than fats

Nice post pboy, but tell me, what is your defenition of "most efficient " ?
You say sugar burning needs more oxygen, but as far as I understand it, for the same amount of netto ATP molecules created, fat burning need more oxygen per molecule ATP than sugar. so in my book sugar is more efficient, ie needs less oxygen than fat.

Such_Saturation said:

Suikerbuik said:

Your doubts are not clear to me. Fat is always entering the cell in some amount.

Click to expand...

If that's to what I wrote before. It's hard to give personal advice. As said it's all matter of context and personal state and the goal someone has in mind.
The 'some amount' is true but depends on concentrations. Sometimes if you want to change things, a change in concentration is needed to induce changes. Also if you can't oxidize this will alter your concentrations compared to other peoples hence need less for the same concentrations..

Click to expand...

Pone's question is not clear, I don't understand.

Click to expand...

Many web sites make the claim that burning glucose will produce 30 to 36 ATP, whereas burning fat will produce more than 130 ATP. You see the claim constantly on ketogenic web sites that burning fat is far far far more efficient in production of ATP than burning glucose. Typical page is this one:

http://www.begin2dig.com/2009/08/respec ... rning.html

So I don't understand why Peat obsesses about the release of free fatty acids during exercise and how he seems to imply that this lowers the amount of energy that the body can produce in aerobic metabolism.