Thursday, July 11, 2024

Protons (74) Arne Astrup and the formerly obese

I have a soft spot for Arne Astrup. Back in the days of the depths of the Danish fat taxation stupidity, he was one of the voices of reason speaking out against the tax. It was a near miss for sanity. Academics have since argued that the tax was repealed too soon (and the sugar tax never got started) and that it was actually "working", at least among those who couldn't hop over the border to buy their (Danish?) butter in Germany. Had it been allowed to continue to "work" we might have successfully forced a whole nation to avoid fat, especially saturated fat. Where might that have led? If you wish to compose the answer on a postage stamp it is just three letters long, which will fit neatly on to even the smallest stamp.

Anyhoo. People may have noticed that I like this paper from the Astrup led lab

Fat metabolism in formerly obese women

mostly because Table 3 confirms all of my biases by showing formerly obese women are exquisitely insulin sensitive, which is pure Protons:

The rest of the paper is more difficult.

The formerly obese are, as expected, only deriving around 35% of their energy from fat oxidation at time zero on the graph below while the never-obese controls are deriving just under 80% of their energy needs from lipid oxidation, time zero again. These values are while sitting still on a bicycle ergonometer, after an over night fast. Not quite basal metabolic rate or resting energy expenditure but pretty close:

It is also worth noting that performing exercise at 50% of VO2 max (previously individually measured) completely normalises energy production derived from fat oxidation. Those are time points 15-60min. All we need here is for AMPK to instigate oxidation of the fatty acids available while suppressing their formation. Then the pathological insulin sensitivity is bypassed. There are several posts possible on AMPK but again, here is not the place to explore the control of insulin signalling by AMPK and vice versa. Both happen.

Finally, the really strange thing is that these formerly obese women have modestly *elevated* FFAs, both at rest and throughout exercise, consistently around 300µmol/l greater than controls.  If the formerly obese have all this extra lipid available, why don't they oxidise it?

We can say, quite conclusively, that these FO women have normal electron transport chains. Under exercise they oxidise lipids exactly as well as control women do. My assumption is that there has to be a signalling problem which is inhibiting fatty acid oxidation but can be over-ridden by AMPK activation.

We know, from a mass of rodent and human studies, that when you allow a subject access to carbohydrate food (or an OGTT) after an extended fast, they perform de novo lipogenesis, giving an RER > 1.0, for about an hour. The duration is interesting. Insulin-induced insulin resistance (which is complex and probably involves the glycerophosphate shuttle) usually comes in to effect at around about an hour in many models. This will reduce insulin signalling from its peak action under "hungry" conditions to a more moderate "fed" signal.

So peak insulin signalling after a fast, but before establishment of some physiological limitation, is a potential major driver of de novo lipogenesis with storage as triglyceride and, as we shall see, an effective inhibitor of fat oxidation.

Mechanistically we have to look briefly at the Randle Cycle.

Two of the many actions of insulin are to activate the pyruvate dehydrogenase complex and the acetyl-CoA carboxylase complex. This generates malonyl-CoA which inhibits CPT1 mediated transport of fatty acids in to mitochondria. Hence FFAs are available but not oxidised. But there is no problem with the mitochondrial ETC itself, all that is needed is for the insulin signal to be reduced.

During that initial refeeding period both the RQ of >1.0 and the inability to oxidise lipid can be viewed as manifestations of marked insulin sensitivity. Carbohydrate uptake is enhanced by insulin and the products of this carbohydrate catabolism are diverted, by insulin, to metabolites which inhibit fat oxidation and away from the Krebs Cycle and the electron transport chain.

Aside: My interest is in ROS based control systems so I have tended to ignore such details. But here the downstream effects of excessive insulin signalling on the Randle Cycle do matter. My bad. End aside.

My premise is that obesity is cause by a pathological sensitivity to the hormone insulin, mediated by linoleic acid. If this is correct then we would expect pathological lipid synthesis/storage to be combined with an inhibition of fatty acid oxidation. The normal "one hour" of peak insulin sensitivity is extended or even becomes continuous by using linoleic acid as a significant energy source (pax uncoupling intakes).

Here we have the formerly obese who are, without a doubt, destined to become obese again in the future. We also have people with obese parents who are not yet obese themselves. Both show the accentuated insulin sensitivity in combination with depressed fatty acid oxidation, both at rest and post prandially. All that is required to do this is to allow insulin to continue to act at peak efficacy under conditions where a functional limitation should have been imposed. Linoleic acid replacing palmitate/stearate under the Protons hypothesis provides exactly this.

So, in Astrup's particular group of formerly obese subjects described in the current study, it has proved possible to have inhibited fatty acid oxidation with sufficient severity that it leads to elevated plasma FFAs, because they cannot be used for energy generation. All as a consequence of augmented insulin signalling.

This particular group of FO subjects do appear to be a rather extreme example. Other FO people assessed by Astrup's group in previous studies do not feature the elevated FFA or profoundly depressed fasting insulin aspects, though the inability to oxidise lipid to produce adequate energy is a consistent feature over many studies. I think this current group of women are probably outliers who give an insight in to mechanisms. That's good.

It's also clear that these formerly obese women have a metabolic rate under fasting conditions significantly lower than that of the never obese controls. This is not surprising. Fat oxidation is being largely inhibited by elevated malonyl-CoA and a significant portion of glucose is being diverted from energy production to form that malonyl-CoA and its derived and stored lipid.

The FO women's resting energy expenditure is 3.77kJ/min, ie 0.9kcal/min, 1296kcal/24h. Never obese women expend 4.88kJ/min at rest, 1.2kcal/min, 1728kcal/24h. Except of course the FO women are not oxidising fat, because they are unable to effectively oxidise FFAs. They are using glucose.

So they are 461kcal/24h "hungrier" than never obese controls and are running on limited supplies of glucose from glycogen. The obvious solution is to access more glucose, which insulin has actively locked in to the liver/muscle stores of glycogen.

Traditionally this is solved in the real world by raiding the fridge at 3am. For something sweet. Much of which will be diverted to storage.

Weight gain.

It happens.



Tucker Goodrich said...

One wonders how they became formerly obese. I presume it was through calorie restriction, and not LCHF or ketosis?

I've always considered the keto flu that people often report when initially going ketotic to be a process of shifting mitochondrial oxidation from glucose to fat. It takes some amount of time for the mitochondria to restructure and to access fat stores.

Of course calorie restriction alone regardless of diet, is enough to cause insulin sensitivity...

mct4health said...

Yes, Peter, that's right. Activated ACC1, not phosphorylated via AMPK is THE problem. Then you can evaluate cytosolic acetyl-CoA. Fat synthesis depletes it. And this stabilizes normoxic HIF1A, and HIF1A promotes fat synthesis and activates NOX2. we have THE switch. You still don't need HIF1A? This pathogenic insulin sensitivity could be only shift caused by NOX2.

Passthecream said...

As a formerly obese person myself I resemble many of your remarks. Ruthlessly eliminating pufa and sugar, generally lowering carbs and being active did the trick.

I'm doing the mental algebra; if the 0.5g effective difference was continuous over 24 hours it would amount to 720g of fat deficit, or fat bonus. Pufa is a powerful lever! Beyond algebra there is the hint of a simple integral/differential algorithm here, where it might be possible to juggle the levels of the various factors+actors you outline. It's not as simple as arithmetic, more in the style of Bill Phillip's Economy type of gurgler, Moniac. It's not for no good reason that they call them 'fat deposits', it's money in the bank :)

karl said...

It is important to mention which tissue when talking about insulin resistance - the liver can be resistant at the same time adipose tissue is sensitive.

A few details - high LA diets damage the liver - as does high Fructose - but the combination synergistic combine to do much more damage. (can't find my reference??)..

I am thinking that some of this damage is permanent. (is this correct?)

One of the effects of the damage is reduced energy storage capacity of the liver - (normally about 400cal) The muscles also store energy - about 4x that of the liver. One can probably make up for the lose of storage by increasing muscle mass.

So when the liver gets damaged (think some amount of NAFLD) liver tissue becomes insulin resistant ( is this due to storage being full?) - the liver leaks glucose and FFA - at the same time adipose tissue can be hyper sensitive from the high LA diets. Is this experienced as fatigue? Because the normal storage and release of energy as meals come and go isn't working? Fatigue tends to send people to the kitchen to eat more.

I'm also wondering if muscle tissue can get damaged by T2D - again reducing energy storage capacity?

I think the definition of T2D should be chronically elevated insulin. When insulin is always high - the normal regulation doesn't work correctly.

My thinking model is that the liver becomes insulin resistant first - muscles second - and adipose tissue last.

So Tucker might be wondering if weight loss with out LC which would stop LA consumption? Because of the long half life - cutting LA may not make noticeable differences quickly - and humans don't seem to notice long term effects.

I'm not clear on exactly what type of damage the liver gets as people move towards NAFLD - could be 4-HNE - could be just the fat? Lots of possible narratives. (NAC might help remove 4-HNE? - I can think of important studies we could use here)

My experience is once the damage is done, eating LC permanently might be the best response? If I eat even a small amount of carbs, I tend to start gaining weight I don't need. In my situation, I lift weights - have lowered my fasting BG in the lower 90s - even if I eat a dose of carbs my BG does not go over 100 - yet my weight will creep up with only 100g of carbs/day.

The medical community has no consensus about exactly which tissue is damaged in T2D - lots of narratives. I think the liver is currently the best supported suspect - but my list of hypotheses is quite long.

If we muck up the protons-switch with LA consumption - moving between growing mode and burning mode - thus energy storage is in dis-regulation.

Peter said...

My thanks to Paul for the heads up that I goofed on the kJ to kcal conversion. Very embarrassing but easily corrected. Numbers look good.

Tucker, one aspect of keto flu I suspect. Ultimately an acute cellular hypocaloric state should activate AMPK and instigate synthesis of more FAO machinery. Oh, the weight loss was a via an high protein, high carbohydrate conventional diet. I suspect that some people were more assiduous avoiders of saturated fat so go hit really badly by hypometabolism and depressed fatty acid oxidation. But we have no data of the fat composition of normal diet or the run-in diet to the study.

Jaromir, my brain keeps pulling it back to RET. I have no doubt we are talking about the same thing.

Pass, that's interesting. I screwed up the arithmetic, it's fixed now. The BMR deficit is ~450kcal/24h. Enough to need a bowl of ice cream at 3am. And yes, agree that it's absolutely more complex than arithmetic!!!!

karl, the big question is whether high fructose or high alcohol diets are in any way liver toxic in the absence of obesogenic levels of LA. Currently I suspect not. If you overload the liver with calories it exports them is VLDL. The lipid for VLDLs are retained in hepatocytes by insulin, and pathological insulin sensitivity retains excess lipid when it should be being exported. W/o LA the liver gets calorically overloaded and just dials up FGF21 and exports the calories, indirectly, via BAT or directly as VLDLs. LA is core.

It is very slow to reverse LA stores in the body which makes the problem permanent and it's only in the last few years LA has become accepted in the weird (that's us!) fringe as being a core cause of obesity. Probably *the* core cause. There may be genetic differences in how people handle LA. That's interesting and might have some bearing on who has more need for LC/keto than others.


mct4health said...

About fructose, it has special ability to elevate lactate and uric acid. If we need AMPK for repairing the FO metabolism, uric acid suppress AMPK, so fructose via AMPD and uric acid makes fixing impossible. More about it here.

Passthecream said...

Mct4health, salicylic acid also elevates urate, don't know what other sequelae it might have, irc carcinogenic in some contexts. It is of course common in plant foods, being a plant hormone. Don't take aspirin for gout!

Passthecream said...

Peter, so it's an interesting question as to what happens to the exact levels of everything as they evolve over time if you took that 450kCal as 50g of butter or as 113g of boiled potato, or some mixture in between those two extemes. (Not to mention a glass of peanut oil, yuk.)

Passthecream said...

Edit; I missed making my point there. If you get your fructose from fruit you also get a lot of salicylate so it's a confounder as far as uric acid is concerned. You're also likely to get a lot if sorbitol, another urate confounder.

Peter said...

Jaromir, this is exactly why I tend to stick to ROS mediated control. Why does fructose facilitate (mimic) insulin signalling? Because it signals by a currently unidentified kinase to a currently unspecified member of the family of NOXs to mimic insulin signalling. Which kinase and which NOX is unimportant, it happens. Significantly elevated levels of fructose will signal through the same mechanism to generate ROS at levels to inhibit insulin mediated glucose ingress facilitation, in proportion to the calories being provided by fructose which are replacing glucose. Further downstream is the activation of uric acid oxidase and subsequent ROS generation and frank insulin resistance. I absolutely accept that intermediary metabolism matters, it just doesn’t supply a pragmatic answer to the complete balls up of caloric sourcing by humans under the idiotic influence of 1960s cadiologists. Without LA the balance between glucose and fructose would work perfectly well under the levels of exposure likely to have been available. Which could be quite a lot of honey at times.

Pass, the other confounder is that salicylate is a marked uncoupling agent, 1956, a good year,

However aspirin, which is the acetylated form, will not have the acidic -COOH moiety which is needed to pass protons across the inner mitochondrial membrane. I suspect a small amount of aspirin is deacetylated to salicylic acid but not the bulk, which is poor at uncoupling.

Re spuds vs butter, in the short term neither would help. Butter is complex and pure carbohydrate will elevate the already over effective level of insulin. Long term lowering of insulin and its signalling is needed, ie LC is a “fix” but long term reduction of omega 6 should be the goal.


Passthecream said...

Aspirin is acetyl salicylic acid but perhaps the proximity of the acetyl group, one carbon around the 6C ring from the carboxyl group, interferes with that as you suggest. It is converted ("salicylic acid is a major metabolite of asa in vitro" - lost the ref) also readily decarboxylated by various biological processes eg OH will decarboxylate and hydroxylate etc. There is some tie-in with xanthine oxidase, another ominous participant.

But the main reason it is not good for gout is that it increases kidney retention of uric acid. I have verified by personal experience! The downside of the 50s is that we were awash with Aspirin rather than Tylenol and I have the tinnitis to prove it.

Terrible stuff, best avoided.

Re: LA; preaching to the choir, Amen Brother! I have not drunk it for many many moons, full member Linoleics Anonymous.

mct4health said...

Peter, looks like it's not some NOX but it's XO what produces H2O2 caused by fructose with involvement of LA oxidation products.
'Novel role of xanthine oxidase-dependent H2O2 production in 12/15-lipoxygenase-mediated de novo lipogenesis, triglyceride biosynthesis and weight gain'

Peter said...

Interesting Jaromir.

Also the uric acid produced by XO induces ROS generation by NOX4 translocating to the mitochondrial membrane and being activated....

Ultimately modest ROS -> adipogenesis, high ROS -> IR

There are several tools and steps, it seems.


karl said...

RE Uric acid via low dose ASA:

My hunch is it isn't a problem for people with normal levels of insulin, but if not:

From GPT4o ():
Insulin itself influences the kidneys by reducing the excretion of uric acid. This effect is thought to be due to insulin’s action on the renal tubules, where it can increase the reabsorption of uric acid, leading to higher serum levels. Thus, hyperinsulinemia (high levels of insulin in the blood, often associated with insulin resistance) can lead to hyperuricemia (high uric acid levels) by reducing the kidneys' ability to excrete uric acid.

I would warn that this might be confounded with sodium excretion - insulin causes sodium to be retained.

OT a bit:
I've noted that on an endocrine level, how the body works is hyper-complex - nested and redundant feed-back loops are the rule - not the exception. Everything interacts with everything so papers that find an association between X and Y - and then often infer causation without the hard work of establishing the low level mechanisms mislead us. Thus there is a lot of 'hand-waving' papers with ungrounded narratives that are more about ego than science.

I've been reading about the advancements in what we know on the cellular level - how DNA actually works. The narrative that the DNA encodes amino-acid strings that fold into defined proteins - while sort of true - is misleading. There is a lot of RNA editing - variable Splicing - lots of 'disordered proteins' (they have floppy bits that can combine with multiple targets). A lot of DNA codes for RNA that is used to block other DNA - and there is RNA that is simply regulatory - not transcribed into proteins. It appears that the DNA might be thought of a library, but much of 'life' is actually at a different level. Understanding how non coding RNA works is more important than DNA.

Once again - even on a cellular level, feedback loops appear to be redundant/nested hyper-complex. I think we see 'emergent phenomena' - ( see )

My current thinking reminds me of how a neuron works - (they use neural networks that simulate a neuron in the LLM (miscalled AI) and the people that produce LLM don't actually 'know' how they work - at least on an intuitive level.) Training is sort of a black-box art to produce emergent functions.

So I'm thinking that not just Neurons - but all cells have the functions of memory, and computation - it is just that we expect it in the brain - but not other cells.

(Important to note that human cells are actually quite different (lots more disordered proteins ) than single-cell eukaryotes )

Anyway, the expectation that once we decoded the genome that we could find the genes for everything was misguided - why cancer gene narrative went down with a flop. There is obviously at least one more level of biology between DNA and life that we find in our cells. (and have little understanding)

For understanding the proton-switch this means it could be possible that there is epigenetic data within cells that gets changed by eating linoleum feed-stock. I'm still wondering where exactly the damage is in T2D...

mct4health said...

Peter, but ROS level from fructose I see only as the starter, without activation of pseudohypoxia via HIF1 it means nothing, only short term adaptation without long-term effect. Like in the XO paper, when XO would be deactivated on already obese mice, it would not work. Like in FO woman.
That's why I concentrate now how acetate on mice works, because it can reset pseudohypoxia, so repairs already changed processes. Likely via acetylation of HIF1A.

Gyan said...

The controls, presumably not in ketosis, are getting 80 percent energy through fat oxidation. How much more adaptation to fat-burning is required?

Gyan said...

Dr Eades has further thoughts on how visceral fat is inflammatory. As the fat cells become big, they get hypoxic and induce angiogenesis. Which induces the white blood cells and thus the whole inflammatory cascade.

mct4health said...

I think it's not correct. Fat cells become pseudohypoxic with normal oxygen supply long before they get big. It's proved by HIF1 KO in mice adipocytes. If they would switch on HIF1 as they get big, cells would be big, but they aren't. They are small. This proves they have to be switched already in normoxia by changes in metabolism, e.g. via lack of cytosolic acetyl-CoA. And since then they get bigger and bigger. It happens in waves, seen on graph of cell sizes.

Gyan said...

New research discovers a subset of beta cells display large insulin response to lipids.
"Proteomic predictors of individualized nutrient-specific insulin secretion in health and disease"

mct4health said...

Insulin secretion is very complex

I see switch to diabetes as loss of lipolysis regulation. Normally IS is stimulated by FFA, but in high glucose environment beta cells suppress IS by FFA. So control of lipolysis vie insulin is lost. But control via H2O2 possibly stay active, nobody talks about it, IS is stimulated by H2O2 and lipolysis is suppressed by H2O2, big question.

Passthecream said...

Karl, one for your amusement:

(PDF) The Merging of Biological and Electronic Circuits

'Biological circuits and systems within even a single cell need to be represented by large-scale feedback networks of nonlinear, stochastic, stiff, asynchronous, non-modular coupled differential equations governing complex molecular interactions.'

Passthecream said...

Karl, "I've noted that on an endocrine level, how the body works is hyper-complex - nested and redundant feed-back loops are the rule - not the exception. Everything interacts with everything so papers that find an association between X and Y - and then often infer causation without the hard work of establishing the low level mechanisms mislead us. "

It's a very human way of understanding, to kick the tyres, tap on a piece of wood, and you can get useful information about the nature of a complex system without understanding the minutely detailed physics of it by impulse testing it, which was the simple thought behind my what-if question ie what if you start with an exquisitely insulin sensitive f.o. person and provide a fat impulse or a starch impulse or etc. What happens next? Complex living organisms are interestingly long-term stable in view of the speed and responsiveness of their constitutional processes and there are many different types of impulses but in keeping with what you suggest, by the nature of the behaviours of emergent systems with simple inputs vs outputs we can find a match between the complex way that people understand things and the broad characteristics of those systems.

karl said...


On the electrical biology - bleeding edge understanding..
One of the thing they are finding are protein networks - there are voltage gated channels, and 'gap junctions' (specialized intercellular connections that allow direct electrical communication between cells. They are formed by connexins, which create channels that permit ions and small molecules to pass between adjacent cells, facilitating synchronized activity.)

The same control network confounded mess found in the endocrine system - is also found in these low level cellular systems. What I thought I humbly knew about biology keeps getting reset by new layers of complexity. I'm not sure, but it seems the 'thinking' part that goes on in biological neural networks is just an extension of the processing capabilities of other cells.

"The interactions within protein networks can give rise to emergent properties that are not predictable from the properties of individual proteins. For example, feedback loops in signaling pathways can lead to bistability, where the network can exist in two stable states."

There is an amazing system that happens as tissue types differentiate - look up 'Sonic Hedgehog (Shh) signaling pathway' - it is a deep rabbit hole that does not really have a bottom at this time. Or dig into Bone Morphogenetic Proteins (BMPs(not really limited to bone)) Or DNA methylation (an epigenetic mechanism). Every peel back to understand how cell-life works ends up as a new layer of complexity.

Anyway, my hunch is the changes that cause T2D are in the liver - and it seems that the changes are not completely reversible. Humans notice acute toxicity - but can fail to make the association with gradual harm. It has been profitable to get people to believe that linoleum feed-stock is human food.. things that do slow harm are sold under GRAS. It is going to be hard to overturn the dietary advice to eat LA, a slow poison that lowers cholesterol - Way to many living that have egg on their face - invested egos.

Passthecream said...

There us something far simpler than all the arjy barjy and complex permanent damage, which I feel qualified to mention since I am a member of this not so exclusive f.o. club. In those areas which were once full of plumpness I now resemble a saggy baggy elephant. At my age the skin is probably not elastic enough to snap back into trim and tgere are stretch marks too. There has been talk here in the past about fat cells being potentially immortal ; obviously not immortal in the sense that dumb adopocytes might eventually rule the world, rather that they don't ever seem to die off much; they're probably too important for survival in an evolutionary context. But once you have them and they have shrunk they are part of what makes one extremely insulin sensitive. They are in perfect working order, just empty and awaiting further input.

Those drugs that "cure" t2dm by proliferating fat cells, well that's just asking for trouble!

Gyan said...

Diabetes is said to involve damaged mitochondria. Per metabolic theory of cancer, the damaged mitochondria are central to cancer as well, by leaking free radicals they cause nuclear genes to mutate.
Then why there never is genetic damage and mutations in diabetes?