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Intermittent and extended fasting

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
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For those of you perhaps wondering in your head if CGM is right smack in crazy town:

The point of all this fasting and lowering carb business is to achieve lower glucose over time, and thus lower insulin over time. These are empirical methods of getting this done.

CGM is just the next step up in data to achieve this very same goal consistently, when used in this context for non-diabetics. It’s the continuous integration of the same data I strove to acquire with my carb challenge.

I think it’d be kind of amusing to show up to my PCP appointment on Dec 18 wearing a (self-prescribed) CGM monitor. At least then I could show hard data other than the two crappy data points of height and weight taken by their MA.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
This is a fantastic video re risk of high LDL-P if otherwise metabolically healthy

 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
Just called Dexcom to start the ball rolling on acquiring a G6 CGM. Turns out it’s a two step process: established an account with them on this phone call, answered some non-relevant questions (“what kind of diabetes do you have?” “None” “Can we get your insurance information?” “Not needed, as I’ll self pay as they won’t reimburse since I don’t have diabetes”), and provided them with my doctor’s info (me). Someone else with more domain-specific knowledge as opposed to the front line call lady will call back or email within 24 hours and continue this process.

Also ordered different lancets from a medical supply company. The tiny lancet used with the wife’s 0.6 microliter per test glucometer was entirely insufficient for the 40 microliters of blood that the Cholestech LDX needs. These new ones are much more serious business, 28 to 21 gauge, 1.8 to 2.0 mm depth. That’ll bleed, alright.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117

They only lasted 4 days in their fast before caving.

Amateurs.
 

SkaredShtles

I love NEWCASTLE and will ONLY drink NEWCASTLE!!!!
Sep 21, 2003
48,971
2,978
In a van.... down by the river

They only lasted 4 days in their fast before caving.

Amateurs.
They probably don't have anything on their bodies to ketoninate.

:p
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
They probably don't have anything on their bodies to ketoninate.

:p
That's totally not a word! (The process is of lipolysis, ketosis, then ultimately oxidation of ketones.)

Anyway, here's one of the activists from said group:



He's got a couple weeks' worth of fasting stores there.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
I picked up machine #2 from the post office today (machine #1 having been DOA). This one works!



Results from draw #2 (#1 having been the one just before I figured out that machine #1 was broken):

Context: Fasted 17 hours. Ate probably 150 grams carbs the day before, but also much of a lovely wagyu hybrid ribeye at dinner, so not a keto day for sure but not SAD, either.

Total cholesterol 263 mg/dL

HDL-C 25 <— I am guessing this is artifactually low as I’ve never been below 45 before

Triglycerides 53 (!!)

Calculated, corrected* LDL-C of 168
Relevant to others who may follow down my path, or who even get standard labs while on a similar diet:

Note the asterisk and “corrected” for that LDL-C. What the machine spit out was 227, but that’s because its assay (like most even used in real labs) doesn’t measure LDL-C directly. Instead it calculates it via the Friedewald Equation, which is:

LDL-C = [total cholesterol] - [HDL-C] - [non-HDL cholesterol] / N

Where N = 5. (This last term yields VLDL, for the curious.)
The problem with this equation is that the relationship between non-HDL cholesterol and VLDL falls apart in the setting of very low triglyceride values. How to correct it comes via a lovely JAMA paper that published a table of N (from the equation) values for different pairs of triglycerides and total cholesterol.



From this table and my values today N = 3.4, thus 168 mg/dL corrected calculated LDL-C. Quite a bit different, eh?
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
Nothing super new here but a nice overview:

 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
Now for a Sunday mini science dump, most of these from diving down rabbit holes this morning before the kids awoke and I arose:

1) Eating a high-bacon diet is protective against colon cancer precursors, at least if you are a rat.

2) More on the whole “metabolic health changes how we should interpret individual biomarkers” bit with regard to lipid metabolism:

A) Small dense LDL (sdLDL, or “subclass B” in this paper’s terms) is what drives atherosclerosis, in part through screwing with NO/ONOO- ratios.

Conversely, large buoyant LDL (lbLDL, “subclass A” here) fixes those NO/ONOO- ratios so is protective… even though both are measured as part and parcel of LDL-C as a whole.

B) Who has bad ratios of sdLDL and lbLDL, with too much sdLDL? Did you guess people with metabolic syndrome or outright type 2 DM? Because you’d be right.

(See a pattern here? Insulin resistance really is the driver behind so many things!)

C) What’s worse than sdLDL for causing atherosclerosis? Oxidized sdLDL.

What drives oxidation? Elevated glucose levels. This promotion of LDL oxidation has been known for decades in diabetics, with this paper showing it promoted at 450 mg/dL glucose. But it’s much more than that admittedly very high level that causes oxidation: this group showed increased LDL oxidation in people with impaired glucose tolerance, defined as > 140 mg/dL on a 2 hour oral glucose tolerance test.

Did I make that clear enough? Glucose levels seen with pre-diabetes—which is insulin resistance by definition—increases LDL oxidation and thus cardiovascular disease risk.

D) What decreases LDL oxidation? We can theorize that sustained low glucose levels would do so, thus the whole continuous glucose monitoring idea.

This rather crappy little paper did show that age and BMI-matched patients with not substantially different LDL densities (e.g. not sdLDL-prevalent in one group per points A and B above) showed an association with athletic training and LDL oxidation resistance. They didn’t show why this happens.



Cliffs Notes: For good colon health eat more bacon—attn @SkaredShtles . For heart health: Exercise. Become more insulin sensitive.
 
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Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
Two more to round it out, re utility of low carb high fat in improving lipid markers: Not talking about LDL-C here—pay attention! But rather reducing sdLDL, reducing Lp(a), reducing oxidized LDL and oxidized sdLDL in particular.

This nice 4 week per arm crossover study showed that one month on each diet could demonstrate that low carb high fat diets lead to lower Lp(a) and lower oxidized LDL.

This paper sums up the evidence more broadly, noting that I haven’t read each cited paper in turn:

The assumption that a low-fat diet reduces the ‘bad’ cholesterol (ie, LDL) is an imprecise notion. While total LDL may be lowered with a reduced intake of dietary fat, if replaced with carbohydrate, this may increase sdLDL particles (ie, pattern B),10 ,11 which are more atherogenic than large buoyant LDL particles (ie, pattern A).12 Additionally, data indicate that a high saturated fat intake lowers sdLDL particles and raises large buoyant LDL particles.13 Thus, replacing carbohydrate with fat may improve the LDL particle size distribution (eg, pattern B shifted to pattern A). Lastly, if fat is replaced with carbohydrate, this may worsen the overall lipid profile (decrease in HDL-C, increase in triglycerides and increase in sdLDL particles).10 ,11
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
More re continuous glucose monitoring, and whether there's evidence to support Peter Attia's and my working theory, that "flatlining" as much as possible ~90 mg/dL is preferential if one's goal is reducing cardiovascular disease:



That's from https://www.sciencedirect.com/science/article/abs/pii/S0002870312003134 . These data seem to show that lower is better, even within the nominally normal range. This is evidence for the 90 figure itself, which includes fasted and post-prandial periods.

Then we have this study: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1464-5491.2010.03059.x . This one shows that endothelial function is impaired when glycemic variability is higher, even in the subgroup of people who are fat but don't have DM2 or metabolic syndrome. (Although 30% in this subgroup smoked and 27% were hypertensive, so not quite ideal there. A1C of 5.3% +/- 0.2 in this group.) This is evidence for the flatlining bit, of minimizing the variation.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
I’m planning on fasting from after dinner tonight through Thursday morning or noon, assuming I feel good.
Still on my fast. 72 hours in at this point. I think I’ll resume eating tomorrow morning. Got some things I’d like to eat: shoku pan with delicious Kerrygold butter, some unagi sushi, and who knows what else before afternoon Thanksgiving foods at my sister’s place.

I skied fasted today. 13,000 vert at Copper. Felt fine. Easy pace most of the day as I was skiing with my wife.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117

Fascinating. T cells mediate “obesity memory” in rats. Unclear if true in humans to same extent or what to do about this, but food for thought indeed.
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117
Mini science dump:

1) Vegetable oil leads to obesity. Counteract via adding omega-3s (and avoiding omega-6 vegetable oils in the first place! ubiquitous in packaged foods).


2) Vegetable oil reduces LDL-C... but in reanalysis of the original data it does NOT reduce coronary heart disease death or all cause mortality. Indeed there's a non-significant trend towards higher death, again with lower LDL-C.


3) Half life of linoleic acid (read: high omega-6 vegetable oil) in human fat about 680 days. So if one reduces vegetable oils today then it'll take about 9 years before 97% of it is out of one's fat:

 

Toshi

Harbinger of Doom
Oct 23, 2001
27,246
2,117