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Comment by Aurornis | Hacker News Reader

This test is also being heavily misused and misinterpreted in some online communities. There are a lot of people posting CAC scan results after something like a year of keto dieting in their 20s or 30s and using that to conclude that the saturated fat connection to atherosclerosis is a myth or that high cholesterol is fine.

These tests don’t have perfect accuracy and resolution, so low or zero results don’t mean that a lifetime of high cholesterol won’t catch up with someone in their 60s and 70s, yet a lot of podcasters and social media influencers are making those claims.

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Also age is huge so people shouldn't be reading much into a reading of 0 unless you're over 65. https://dirjournal.org/articles/coronary-artery-calcium-scor... (see table 2)

Imagine claiming "my diet is great, i got 0% on my calcium score" when that just means you have the same score as 95%+ of people at age 40.

By 55, 25% of people start showing some % of calcium and at 65, 75% of people have a reading on calcium score.

So anyone under 45 being proud of a zero score is just silly.

Is this a keto diet that's mainly leafy greens with healthy protein like salmon? Or is this the "keto" diet of bacon and steak and as much fast as one can shove in the food-hole?

I don’t understand why some prople claim that diet does not impact cholesterol. I did ‘keto’ with bacon/steak/chicken/etc for 3 months, got bloodwork done before and after and my LDL went through the roof.

There’s an offshoot of the keto community that has become die-hard cholesterol deniers. They don’t necessarily argue that keto doesn’t raise cholesterol. They argue that it doesn’t matter to have high cholesterol. They believe doctors and science are wrong on the subject. They think statins are evil. They embrace a few fringe doctors who agree with them.

If you do try keto again, bacon and such are the worst way to do it. Getting your fat content from a monounsaturated source like avocado oil can be helpful. Taking statins is also a good idea.

In contrast, I had a high LDL of 190, largely genetic, and panicked and switched to a vegan diet. I had my LDL tested again 10 days later and it was 120. I couldn't keep up with the strict diet, but learned some good habits and to avoid saturated fat. My doctor hasn't recommended statins... yet.

Have you seen/read cholesterol code? It doesn't deny cholesterol but rather has interesting, and unusual findings.

https://cholesterolcode.com/

There’s a good talk as well that presents this information in a very accessible way:

https://youtu.be/jZu52duIqno?si=NCEf4UGtgHG9sBOP

Years ago I also experienced very high LDL after a few months of low carb. A doctor was convinced it was genetic (familial hypercholesterolemia) even though multiple earlier tests over the years had been in the normal range. He had never heard of low carb cholesterol hyper responders and dismissed that diet could have to do with it.

Nowadays I am convinced that what happened was completely explainable by the Lipid Energy Model [0]. Five days a week I was doing 60~90 minutes of cardio in the morning after skipping breakfast. Exercising in a fasted state while on a low carb diet meant that I had very low glycogen in my muscles and liver, which meant that the muscles had to mobilize fat as an alternative source of energy. Since fat is not water soluble, transporting fat through the blood stream requires packaging it inside a micelle wrapped in phospholipids -- a lipoprotein. Hence the elevated LDL & apoB.

The solution is simple: consume some carbs before and/or during exercise, and learn about the translocation of GLUT4 receptors if you are concerned about hyperinsulinemia.

[0] https://pmc.ncbi.nlm.nih.gov/articles/PMC9147253/

no surprise that your reference is from Nicholas Norwitz. It's good he self-owned with the KETO-CTA trial and showed everyone that isn't already bought into the low card dogma that it's clearly a disaster for CVD risk

> keto diet that's mainly leafy greens with healthy protein like salmon?

A ketogenic diet is 70% fat.

It’s literally impossible to get into keto with a diet of leafy greens and salmon. You would have to augment with a lot of fat from some other source and also limit salmon intake to avoid consuming too much protein. Salmon has too much protein and not enough fat to even come close to keto ratios.

You must be thinking of a different diet. A lot of people think keto is another word for low carb, but a real keto diet is very low carb and low protein.

I agree the results after one year of a keto diet don't prove much, but getting that test seems like a good idea. I hope they'll keep testing and reporting the results for years, so we can learn more about the long term effects of a keto diet. And if it does cause problems, they'll want to know ASAP.

CAC tests come with a non-trivial radiation exposure if someone is getting them every few years.

The other problem is that they’re picking and choosing which tests to believe and which to ignore.

They disregard their cholesterol tests because they don’t like the results, but embrace one or two CAC tests because they do like the results (when they’re young).

However the CAC results are a lagging indicator of cumulative damage that has been done. Cholesterol tests are correlated with the rate of damage occurring.

So embracing CAC and using it to justify ignoring LDL and others is the problem.

I think the unknown factor here is whether other benefits of keto over a standard American diet--possibly including reduced inflammation, BP, blood glucose, and body weight--balance out the effect of cholesterol. CAC measures actual damage already done, while cholesterol is just one of many factors.

The downside, of course, is that once the damage is done, it's done, so it's a risk. (And as you said, they won't see the damage in their 20s.)

This is correct advice, thank you. I am reminded once again that correlation != causation and that doing tests 'just to be sure' is not a healthy or safe way to live. There is a lot of literature out this on what makes a good screening test.

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