Metabolic Flexibility - Get Real

(Windmill Tilter) #141

No, you were definitely not carb shaming; that’s not even a real thing. I was making light of the reductionist, ad hominem argument that those of us arguing in favor of retaining the ability to metabolize carbs are nothing more than addicts rationalizing self-destructive behavior with made up words.

I thought it seemed unreasonable, and a bit funny. Sometimes, the absurdity of an argument can be brought to light by taking it to it’s logical extreme. If someone actually believed that supporters of metabolic flexibility are simply carb addicts making up words, then “metabolic flexibility” would be a defensive term, a rationalization. I was trying to imagine what an attacking/offensive made-up word would be. In the current zeitgeist, there is no more cruel and vicious attack you can make than to accuse someone of oppressing or victimizing. Hence the made-up word “carb shaming”. It’s the sort of word a self-deluded carb addict would invent to attack those who would deprive him of his fix.

There is no such thing as “carb-shaming” obviously, and anyone who used it in a sentence with even a hint of sincerity would be laughed out of any room they happened to be in (and rightly so).

An ad hominem argument is wrong because it’s a classic logical fallacy that attacks the speaker rather than his arguments. Attacking an hominem argument is not wrong, because it is an argument put forth against a logical fallacy either directly or by highlighting it’s absurdity. To your point though, the mocking tone I adopted was passive aggressive and less constructive than simply pointing it out explicitly. Sorry.

At any rate, this has been a fascinating discussion that has gotten me thinking about “metabolic flexibility”, which I had never given thought to previously. I’m following it with keen interest.

(bulkbiker) #142

Are you quoting my post for a reason… ?
“If evolution designed us to eat 20% carbs” is the question… not the answer.

(Windmill Tilter) #143

The Pleistocene was 1.8 million years in duration. Homo Sapiens have only existed for 300,000 years. We should probably restrict the discussion to when we existed.

It’s true that vast ice sheets covered much of the earth, and caused extinction events. It’s also true that Africa was minimally affected. It was a temperate climate. Homo Sapiens evolved in Africa. Put differently, our ancestors were happily eating as many carbs as they could find on the African Savannah. They also ate lots of meat. They were omnivores, like most modern humans.

My understanding is that most of those that left Africa did so during the great migration 130,000 years ago during the African “mega-droughts”. They followed the animals . The animals followed the plants. Our ancestors didn’t wander off into vast glaciers; they followed grazing animals. No carbs, no prey. That’s why North America didn’t get it’s first humans until 12,000 years ago. Even if a minor fraction of our ancestors followed the coastlines and lived primarily on fish, they probably would likely have lived much like the “modern” Inuit. Even the Inuit ate 10%-20% carbs. You really think folks liking in temerate or semi-temperate climates didn’t? That doesn’t make sense.

I’m not an expert on any of this stuff obviously, but the thesis that the majority of our ancestors lived in vast plains of ice free from vegetation doesn’t make sense to me.


I second that.


Could “metabolically flexible” also have a broader definition, not just carbs vs fat?

I am quoting FrankoBear from Another Carnivore Thread, where we were talking about anemias. FB wrote this under one of his posts and it made me think… If you eat carnivorously, some can run into a risk of hemochromatosis, but by eating veggies and adding phytates, you actually decrease the absorption of iron and this way decrease the possibility of developing hemochromatosis. Then you have Fangs, Ilana Rose, David and others successfully eating carnivore, each attacking it from different angles as some are focusing on muscle meat, others on 2:1 ration, some nose-to-tail, etc. My friend is anemic and a vegetarian - from what we discussed, she should be decreasing her intake of veggies and increase her meat intake.

I am histamine intolerant and the majority of fruits and veggies are off-limits. The dose makes the poison…a very small amount of veggies delivers a large dose of histamine, oxalates, etc. Keto has done wonders for my symptoms of histamine intolerance and I feel that I do much better with lower carbs, since I can’t have the majority of “carby” foods. No more migraines, no more brain fog, no more swollen hands and feet, no more bloating, etc. I only get blotchy red cheeks when I really overdo it on cold cuts and restaurants. I have been eating sauerkraut without a single reaction from my body whereas pre-keto, I would just look at sauerkraut and my face would be blotchy. Could we say I gained metabolic flexibility because my body can get rid of histamine more efficiently than before and the dose that was my poison is no longer my poison? My body is functioning better, so maybe the loss or decrease in the efficiency of glucose metabolism isn’t a bad thing?

I guess we are only as metabolically flexible as our genes and environmental factors allow us to be?

(mole person) #146

“The Pleistocene is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the world’s most recent period of repeated glaciations.”

We were all over the planet by the end. I think for vast swaths of humanity access to carbohydrates would have been almost nonexistent for most of the year. Even where I live in Canada, in the present day, there is virtually nothing 9 months out of the year.

Wild edibles was a favorite hobby of mine for many, many years. It’s always been something that troubled me. What the hell did the natives eat in early spring, winter and fall? Even in summer natural tubers are really hard to forage much of. And berries, (which I’m sure we always did eat whenever we found them) are only around about two months out of the year. And everything, animal and bird, goes for the berries. It not like an orchard where they festoon bushes untouched.


I like this qualification. It delineates within the nutritional ketosis experiment between the n=1 therapeutic diet for those with metabolic (could add neurologic and immune-mediated?) disease and claims, if any, that it is a broad spectrum species appropriate way of eating.

(Windmill Tilter) #148

Well I was close give or take a few hundred thousand years… I wasn’t kidding when I said I wasn’t an expert. :yum:

The point that we should focus on the 300,000 years our species has existed still stands. Even if we go back 300,000 years, there is the issue of species. We were still interbreeding with neanderthals and denisovans back then. That varied geographically. We were a heck of a lot more diverse back in those days than we are now. After the genocide of the neanderthals and denisovans, the question becomes, where did the bulk of our genetic material come from?

The answer to this question can be answered fairly broadly; from prior humans. Where did the prior humans live? The vast majority of them lived in temperate climates, because that’s where 99% of the food was. You can’t support a very large population on a sheet of ice, but you can support a very large population in warm climates because it contains 1000x the vegetation, and therefore 1000 times as many herbivores, insects, etc. Did people live on glaciers and in vast frozen tundras? Probably, but not many of them.

We see similar patterns in modern times. Less than 1% of the land area supports 99% of the population. From a genetic standpoint, if there were 1 million humans 100,000 years ago, the fact that 10,000 lived in frozen tundra is interesting, but not necessarily important since they contributed a comparatively minor portion of our DNA. If we look back 1000 generations, or even 10,000 generations, the probability that are our ancestors were living in temperate climates eating carbs is overwhelmingly high.

(Michael - When reality fails to meet expectations, the problem is not reality.) #149

(Jane) #150

I appreciated the in-depth explanations of how our metabolism work… but the conclusions at the end to increase metabolic flexibilty was to “eat less… move more”. :roll_eyes:

(Windmill Tilter) #151

This was an absolutely brilliant article that covers a great deal of ground. Thanks for posting this. This one immediately went into my “bookmark” folder. :+1: :+1: :+1:

(PJ) #152

Nice article @amwassil

The ability to efficiently adapt metabolism by substrate sensing, trafficking, storage, and utilization, dependent on availability and requirement, is known as metabolic flexibility. … Metabolic flexibility is essential to maintain energy homeostasis in times of either caloric excess or caloric restriction, and in times of either low or high energy demand, such as during exercise. The liver, adipose tissue, and muscle govern systemic metabolic flexibility and manage nutrient sensing, uptake, transport, storage, and expenditure by communication via endocrine cues. At a molecular level, metabolic flexibility relies on the configuration of metabolic pathways, which are regulated by key metabolic enzymes and transcription factors, many of which interact closely with the mitochondria. … Multiple factors such as dietary composition and feeding frequency, exercise training, and use of pharmacological compounds, influence metabolic flexibility…

They seem to have left out, “a term used by people to rationalize their hedonist desire to ingest more than 10-20 non-fiber carbohydrates a day.” :smiley:

I do respect the detail that the OP of the thread is the one who posted the link to this paper though. :+1: :ok_hand:

At the heart of obesity lies the inability to regulate lipolytic and antilipolytic processes in adipose tissue during starvation and feeding, respectively. … Excess calories are then stored in peripheral fat depots as triglyceride; when these depots reach their maximum capacity and fail to expand, fat accumulates in ectopic depots, including skeletal muscle and the liver. Ectopic fat deposition is related to metabolic abnormalities and defects in insulin sensitivity, T2DM, cardiovascular disease, and cancer. … Finally, obesity is associated with a state of chronic low-grade inflammation because ectopic fat depots release more inflammatory mediators than peripheral fat depots and infiltration of macrophages. Metabolic inflexibility and fat deposition therefore likely reinforce one another in a vicious cycle.


  1. MF exists
  2. MF is affected by diet composition (it says elsewhere in the paper)
  3. greater MF is a good thing

That… seems to sort of contradict the idea that it’s just an excuse. That ever eating more carbs is just unnecessary.

It does not however mean that there are NOT people who DO use it as an excuse, of course. I just… prefer to default to assuming the best, I guess.

(Justin Jordan) #153

As a random aside, there’s evidence that the human population bottlenecked around 70,000 years ago with less than 10,000 individuals. And that homo erectus bottlenecked at 1.2 million years ago with around 25,000

Which may or may not be TRUE, but it’s worth noting we maybe dealing with a much smaller pool of ancestors than many people would guess.

(Ken) #154

It may have even been less than that. The 74,000 year BPE Toba Supervolcano eruption may have taken the human population down to as few as 2,000 breeding.females.

(mole person) #155

You might find this interesting. The current, more popular, theory is not that the Neanderthals were exterminated at all but literally out competed and out bred until they were just a subset of out own genetic material.

I’m not sure of this at all. As @Justin_Jordan points out there was an extreme bottleneck event shortly after the human diaspora out of Africa. Yes, we entered colder climes like Europe in tiny numbers but the evidence suggests that we spread incredibly fast; going from a drop in the bucket compared to the Neanderthals to swamping them out entirely in 20,000 years.

As for where “the food is” that really depends on what you’re eating. The megafauna of the European continent was incredibly abundant while the climate was frosty.

You don’t have to be talking about such climes at all. As I’ve said before, where I live, and where natives managed to survive all the way until near present day, has virtually no human edible plant availability more than half the year. It’s not a tundra though. There is a lot of life. Moose, elk, deer, bear, wolves, beaver (obviously :heart_eyes:) to name just a few. Further it’s fabulously rich in lakes and rivers and fish are to be had everywhere. Canada is in large part boreal forest and it’s cold a lot of the time but it’s not devoid of life at all. Rather, it’s abundant. However, other than the ruminants all of the larger animals do consume a high meat diet.

This sort of environment covered much of the planet during the bulk of the evolutionary history of Homo Sapiens. But more importantly, we spread into those environment. We found them fruitful and thrived in them. I find this rather telling.

Again, no one is saying that a lot of humans were living in tundra. The gradient is finer grained than tundra to balmy plains of Africa and during the Pleistocene most of the planet was pretty cold.

As stated above there was an insanely severe genetic population bottleneck and I don’t believe the assumption that most human lived in Africa after that is born out by evidence.

This sort of assumes the conclusion that we were eating much plant matter when it was available. A lot of current thought is that this may not be true at all and that we were a primarily hunting species. Have you seen the evidence about the nitrogen levels in the collagen of ancestral homo sapiens? It places them as top level carnivores. There are other similar lines of evidence (eg. The acidity of our stomachs, the length of our intestines, as two examples).

Lions live in Africa too but that doesn’t make then omnivores. I’m leaning these days to thinking humans evolved to be something like wolves. We have the capacity for some plant digestion but our early ancestors probably weren’t eating very much of it at all. It may be that it’s not great for us to have very much. The evidence of what happened to our physiology when we shifted to agriculture seems to support this as well.

Anyhow, those are my thoughts these days but, as always, I’m sure they’ll evolve with new information one way or the other.


Zen and the Art of Nutritional Ketosis

I spent many hours today in silence underwater and had a few thoughts (credit to the late Alan Watts).

How do you view your ketogenic diet: As a therapy? Or as a Way? I understand that fickle humans will say sometimes both. That’s where my false dichotomy becomes an argument spiral. But here goes. Playing with some thoughts.

A physician (in the early 20th C pre-antibiotics) would seek to treat and educate her patients with the aim of them regaining their health and not having to see them again.

A member of the clergy would seek to administer and educate their flock with the aim of bringing them back every week and to bring their friends. Thus binding them to the Way and the preacher.

So with nutritional ketosis is it a physician approach or a preacher approach?

This pertains to metabolic flexibility.

The nutritional ketosis practitioner who seeks knowledge to heal, the physician approach, is quite happy to leave and come back to it as needed. They would support the idea of metabolic flexibility.

The nutritional ketosis practitioner who seeks knowledge of the Way of ketosis, the preacher approach, is one who has commited to the Way from the benefits they have witnessed within it. They would not stray. The idea of metabolic flexibility for them is unappealing (for it is not the keto Way).

One way uses keto as a tool, the other adopts it as a guiding way of life.

It is not the nutritional ketosis that is flexible or inflexible, it is the philosophy of the practitioner.

(Ken) #157

Or, you could view the strict ketonian view as romanticized, and the people looking for.metabolic flexibility as analytical.

(Michael - When reality fails to meet expectations, the problem is not reality.) #158

Or vice versa. Even those of us eating sub-20 grams of carbs per day are metabolically flexible. Those carbs get metabolized and utilized. @Don_Q may think he’s become inflexible because a can of beans went through him like a flash flood. But I suspect that initial reaction will be very different within a few days and few more cans of beans. I think the folks who think we need to eat hundreds of grams of carbs on ‘carb up’ days to stay flexible are wrong. The lynx is metabolically inflexible. When the hare population collapes, the lynx population follows. Humans are nothing like that. We do not lose our ability to metabolize carbohydrates by eating mostly fats and proteins. But we do inhibit our ability to metabolize fats and proteins by eating more than minimal and incidental quantities of carbohydrates.

(Michael - When reality fails to meet expectations, the problem is not reality.) #159

PS: My evidence for this is that we all ate SAD for years, many of us for decades. Many people on this forum suffered metabolic derangement and worse for years while eating SAD. Yet, we all switched to keto, most with minimal discomfort. Only some, who were afflicted with the worst metabolic disasters SAD inflicts, did so with difficulty. Not due to keto, but due to the metabolic problems SAD caused them. Aside from strict carnivores, we all still eat some carbs every day, metabolize them efficiently and remain in healthy ketosis. I think that’s good evidence of our metabolic flexibility.

(Empress of the Unexpected) #160

After 2 years keto I can switch things up every month. After a carb month I am in ketosis two days later. I think this is how we were meant to be. While I value being in ketosis, it is pretty obvious we were not meant to live our whole lives this way. HINT: our bodies process glucose happily and easily. Not saying some people dont need keto. Just tired of the black and white.