Perpetual ketosis considered harmful?

[MarcR]

A preponderance of native Arctic populations have a genetic polymorphism that prevents them from entering ketosis. As a result, they are awful at fasting - in one study, metabolically healthy children with the SNP in question became clinically hypoglycemic in only 18 hours without food. Chris Masterjohn explains what's going on biochemically and shares a hypothesis as to why a population that evolved eating a high fat diet doesn't make ketones:

Inuit Genetics Show Us Why Evolution Does Not Want Us In Constant Ketosis

That native Arctic populations evolved to avoid ketosis causes me to be skeptical of any claims that constant ketosis is optimal in the absence of epilepsy, cancer, or some other ketosis-alleviated disease state.

I continue to believe that I will do best if I intentionally vary cellular energy sources over time among glucose, fatty acids, and ketones in order to model more closely the circumstances under which my (non-Arctic) forebears thrived.

[SusanJ]

I saw this, too, and found I mistakenly assumed that Arctic dwellers were in some state of ketosis. Here's a comment I posted elsewhere on my interpretation of his video.

My understanding is that high fat, environmental pressure of the Arctic led to CPT-1a variant, to restrict ketone production and ultimately avoid ketoacidosis in an environment of many other stressors effecting energy metabolism. It did allow for a small drip of fatty acids to get into the liver to support GNG (gluconeogenesis) for brain support, while most went directly to heart and muscle for use (via CPT-1b). His argument is that evolution judged ketoacidosis the higher risk over hypoglycemia. Because the environment was providing pressure through a high fat diet, and evolution selected to reduce ketone production, then his hypothesis is that evolution does not want us on a permanent keto diet. Fasting induced (and impermanent), yes. But he argues that a permanent ketogenic is not the ancestral diet of humans. (And he says he's providing this as context for his next lesson on keto diets that can be used for health goals.)

So, like you and Russ, I'll stick to my eating seasonally (where I can), fasting on occasion and not worrying as much about precise macronutrient percentages.

[NewRon]

https://www.theguardian.com/inequality/ ... ry-success

[apod]

I continue to believe that I will do best if I intentionally vary cellular energy sources over time among glucose, fatty acids, and ketones in order to model more closely the circumstances under which my (non-Arctic) forebears thrived.

This makes sense to me, although I then wonder -- how many carbs and how often? Eg., does it make sense to do ketosis through the winter for a solid 4-5 mo at a time, or does it make more sense to drift in and out every day before a carby dinner... or maybe somewhere in-between on a weekly or monthly interval (with something like a modest 60-90g net carbs or something more like a carb nite's 150-275g) ? Or... does it make the most sense to dig in deep with a several day fast every so often, with years in between.

I'm betting than somewhere along the weekly-monthly axis in that 80-160g net carb dosage range is probably where the sweet spot is, but this is just a hunch. I'm hoping to quantify this to some degree.

I've had a bunch of carbs today to break away from ketosis, and the post-prandial numbers look fantastic, but I'm feeling a little bit of a carbed up headache, and maybe a little nauseous, even. Tricky.

[Stavia]

https://www.theguardian.com/inequality/ ... ry-success

nice!!
I remember a movie from when I was a kid about a Bushman in modern society. The Gods Must Be Crazy.

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[NewRon]

Those bushmen don't sound like they did a lot of fasting, do they?

[Russ]

Oh my goodness, so many angles to jump in on this one, but so little time....

1 - NewRon - Love the "Why Bushmen..." article. Perhaps someday soon we dispense yet with the meat must be intrinsically bad for E4's thing? The population in the article is one where E4 has thrived (~37%). The "avoid meat" hypothesis remains entirely inconsistent with the primary historical record in my view. The variable meat or different meat or whole meat hypotheses are still plausible. On the latter, I've never seen the detail documented for this tribe, but in every other hunter-gatherer tribe, organ meats and fats were most highly prized. But I feel pretty safe assuming they made use of everything on the animal that they possibly could for food, and then other parts for other uses.

2 - Apod - As to variability schedule, seems to me that absent further details, it's not an either short or long thing. I can imagine cycles had varying frequencies day to day that rode along on top of a strong seasonal signal on food availability. I still think the key thing we often overlook is the 'thrifty' hypothesis where this E4 gene would have been an asset, not a liability. http://onlinelibrary.wiley.com/doi/10.1 ... 301.x/full

Also, I shared this interesting paper here long ago [ https://www.apoe4.info/forums/viewtopic ... owe#p10485 ] specifically re study of seasonality in the diet of a different set (Hadza) of Hunter-Gatherers in Africa...

https://s3.amazonaws.com/academia.edu.d ... _impac.pdf

Tubers as Fallback Foods and Their Impact on Hadza Hunter-Gatherers
Frank W. Marlowe* and Julia C. Berbesque
Department of Anthropology, Florida State University, Tallahassee, FL 32306

ABSTRACT
The Hadza are hunter-gatherers in Tan- zania. Their diet can be conveniently categorized into five main categories: tubers, berries, meat, baobab, and honey. We showed the Hadza photos of these foods and asked them to rank them in order of preference. Honey was ranked the highest. Tubers, as expected from their low ca- loric value, were ranked lowest. Given that tubers are least preferred, we used kilograms of tubers arriving in camp across the year as a minimum estimate of their availability. Tubers fit the definition of fallback foods because they are the most continuously available but least preferred foods. Tubers are more often taken when berries are least available. We examined the impact of all foods by assessing variation in adult body mass index (BMI) and percent body fat (%BF) in relation to amount of foods arriving in camp. We found, controlling for region and sea- son, women of reproductive age had a higher %BF in camps where more meat was acquired and a lower %BF where more tubers were taken. We discuss the implica- tions of these results for the Hadza. We also discuss the importance of tubers in human evolution. Am J Phys Anthropol 140:751–758, 2009.

Note especially Figure 3 which shows variability of major foods of honey, meat, baobab, berries and tubers by month of the year...

Marlowe Fig 3 Seasonal Food.png

Perhaps interesting to note that when meat was less available, they ate lots of honey, fruit and tubers - certainly they were not in ketosis during those periods!

3 - Stavia - Yes, I also remember that wonderful film about the coke bottle that fell from the sky and rhinos that stomped out camp fires as the self-appointed firemen of the jungle
https://www.youtube.com/watch?v=OZ81dcD1N8s

Russ