Tag Archives: ketones

the insulin-obesity hypothesis is under attack

…but it isn’t dead, imo, because that would be really hard to do.  Like, seriously.

 

 

side note: please consider the modern views of Taubes, Lustig, Gardner, Attia, and others on Carbs™.  They’re less “Carbs-cause-obesity, keto-for-all, etc.,” and more thinking it might not be Carbs™ per se, but rather processed and refined foods.  And #context…  And I tend to agree at the moment (nuances and caveats are subject to change, as more evidence accumulates).

 

disclaimer: I haven’t seen the full text of Hall’s recent study, but that’s not really relevant to what I want to discuss.  In other words, I don’t think the full text will provide any additional details on this particular point.

 




 

Tl;dr: this study was not designed to prove or disprove metabolic advantage or the insulin-obesity hypothesis.

It’s in the study design:  four weeks of low fat followed by four weeks of low carb.  We KNOW that weight loss slows over time (especially if calories are controlled, as they were in this study).  It has to do with the order of treatments.

Weight loss-slowing over time in the Minnesota Experiment:

 

 

Minn-Starvation-weight

 

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Rodent keto studies

Next time someone says VLC/keto is harmful or at least not helpful for fat loss because of a new rodent study, they’ll probably be wrong.

BOOKMARK THIS ONE GUYS.

Rodent studies on ketogenic diets or exogenous ketones are valuable and interesting in a variety of #contexts, although I’d argue that regulation of fat mass isn’t really one of ’em.

For starters, rodents aren’t particularly ketogenic – it’s rare to see ketones >1 after an overnight fast even in long-term ketoadapted mice.  Also, many rodents gain weight until they die, whereas humans plateau and stay relatively weight-stable for their entire lives (at least historically, and I’m not talking about yo-yo dieting).

Skeletal muscle, on the other hand, seems more similarly regulated: keto isn’t muscle-sparing in either specie… most people, perhaps unwittingly, increase protein intake on keto, and THIS spares muscle (N.B. this is simply to spare muscle, whereas in non-keto dieters, it’s not uncommon to see increased muscle in the #context of high protein).  That’s because carbs are more anabolic than fat.  QED.

There’s just a fundamental difference in the way fat mass and appetite is regulated between the species.  There are many similarities, which is why these studies are still valuable, but fat mass isn’t one of ‘em.

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Ketone supps

1st Generation: ketone salts.  Only problem is the huge dose of salt limits how much you can take without adverse effects… but these are the ones on the market.

 

2nd Generation: ketone esters.

Advantage: no salt, and probably “slow-release.”

Disadvantage: gonna be WAY more expensive than the salts (which are still pretty expensive).

 

 

~40 grams of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (a ketone ester) (from Clarke et al., 2013):

 

ketone ester

 

They did this thrice daily, so some people were getting up to 170 grams.

ONE HUNDRED SEVENTY GRAMS

 

[keep that number in mind]

 

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Ketosis is a hack: here’s why

There are multiple distinct flavors of diabetes/obesity, as evidenced by the fact that some people have: 1) impaired glucose tolerance (but normal fasting glucose); 2) others have impaired fasting glucose (but normal glucose tolerance); and 3) others have both.  This means there isn’t a linear relationship between these phenomena*.  There are also: 4) obese patients with normal glucose metabolism; and 5) lean patients with type 2 diabetes.

*I think the great Dr. Kraft may have missed some of the nuances here.

There is not 100% overlap among these, suggesting [confirming] distinct diabetes/obesity phenotypes (and probably causes & best treatments).

 

 

midnightsun

 

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Dawn PheNOMNOMNOM

Many pre-diabetic, diabetic, and insulin resistant people have used the low carbohydrate diet to successfully manage their blood glucose levels.  It just plain works.  FACT (P<0.05).

However, a small subset of this population fails to achieve normal fasting glucose.  This is likely due, in part, to a type of circadian mismatch induced by aberrant meal timing and excess exposure to artificial light at night.  For an extensive list of citations supporting the former, see “Afternoon Diabetes;” stay tuned for evidence of the latter.  In brief, a combination of delaying food intake for as long as possible after waking in the morning (“skipping breakfast”) and consuming most calories at night = no bueno.  These behaviors can also promote a circadian mismatch and phase delay.  Hint: eat when the sun is up; sleep when it is down.

 

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Carbs: Low vs. Lower

 

 

This was met with much backlash from the low carb cavalry, because, well, if low is good then lower must be better

I’m not anti-keto; but I’m not anti-science.  FACT.

 

“…some people are not genetically equipped to thrive in prolonged nutritional ketosis.” –Peter Attia

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Ketone bodies as signaling metabolites

*non sequiter*

One of the ways dietary carbohydrate contributes to liver fat is via ChREBP: “carbohydrate-response element binding protein.”  It responds to a glucose metabolite and activates transcription of lipogenic genes.  Insulin helps.  Ketones do the opposite (Nakagawa et al., 2013), by inhibiting the translocation of ChREBP into the nucleus where it does it’s dirty work:

 

ChREBP

 

More interestingly, ketones are histone deacetylase inhibitors (HDACi)… this leads to more histone acetylation.  Benefits of fasting sans fasting?  Modulating of acetylation is a MAJOR regulator of circadian rhythmicity.

Butyrate is another HDACi, so have some fibrous plant foods with your red wine and dark chocolate.  Anti-aging (mostly worm studies, but still).

 

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Ketoacidosis

Nutritional ketosis is a normal, physiological response to carbohydrate and energy restriction.  A ketogenic diet is an effective weight loss strategy for many.  Ketoacidosis, on the other hand, is a pathological condition caused by insulin deficiency.  The common theme is low insulin; however, in ketoacidosis, blood glucose levels are very high.  Ketone levels are elevated in both states, although are 10-20x higher in ketoacidosis (~0.5-2 vs. > 20 mM).  Nutritional ketosis and ketoacidosis should not be confused with one another, and a ketogenic diet doesn’t cause ketoacidosis.

In ketoacidosis, gluconeogenesis occurs at a very high rate and the lack of insulin prevents glucose disposal in peripheral tissues.  Skeletal muscle protein breakdown contributes gluconeogenic substrates, exacerbating the problem.  This can cause blood glucose to reach pathological levels, exceeding 250 mg/dL.

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Impact of a low-carbohydrate, high-fat diet on gut microbiota.

NPR recently reported on a study where the participants ate either a meat-based, fiber-free ketogenic diet or a vegetarian diet and had their gut microflora analyzed.  The low carb diet was much higher in fat, and as such, increased the prevalence of a microbe involved in fat digestion.  “Bilophila.”  The article focused on this one and cited a 2012 study where Bilophila was associated with intestinal inflammation… however, the ketogenic diet increased the levels of Bacteroides and decreased Firmicutes.  These are the two that brought the whole gut microbe-obesity connection into the spotlight.  The microbiome in obese mice is characterized by low Bacteriodetes and high Firmicutes. Fecal transplants from obese mice to lean mice causes them to gain weight.  Little is known about Bilophila relative to Bacteriodetes & Firmicutes, and I suspect the focus was on Bilophila because the authors wanted something negative to say about a meat-based, fiber-free ketogenic diet, and that 2012 mouse study suggested Bilophila could be their answer.

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Dietary protein does not negatively impact blood glucose control.

“Dietary protein-derived amino acids have a purpose, and that purpose is not carbs.”

At a reasonable level of dietary intake, protein is used for the maintenance of organs & tissues.  Lean body mass.  It’s functional.  Protein isn’t stored in any appreciable capacity, and most excess is either oxidized or stored as glycogen.  Theoretically, about 50-60% of protein-derived amino acids can be converted into glucose, mathematically, but it’s not what you think…

“At a reasonable level of dietary intake.”  A recent publication took a look at this (Fromentin et al., 2013).   They set out to determine how much protein is converted to glucose under “optimal gluconeogenic conditions.”  That is, the subjects were 12 hours fasted, which is a physiologically relevant, optimal gluconeogenic condition.  They were then given 4 eggs (~23 g protein) that were labeled with two stable isotopes (15N & 13C, derived from hens fed isotope-enriched diets!).  Throughout the entire study duration, the subjects were infused with a third isotope, 2H-glucose.  By collecting and analyzing the enrichment of isotopically-labeled metabolites like expired CO2, urea, and glucose, the researchers were able to determine the fate of those 23 grams of protein.

Some of the dietary protein-derived amino acids were used for protein synthesis, others were oxidized.  But blood glucose levels did not change.  Nor did the rate of gluconeogenesis.

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