Jun 13

Carotid Artery Update, SAD Diet Edition

[UPDATE — 6/14/18 — I’ve added further data and some study comparisons below!]

Of all the metrics I’ve been wondering about following my Weight Gain Experiment, CIMT certainly ranks in the Top Three. I speculated several times that I wouldn’t be surprised if it had an impact. But how much?

The Jury is in:

Lots to unpack…

First thing’s first — I always knew and have stated several times publically that this last experiment could have short and long-term risks, which is why I’ve been very vocal that I don’t want anyone else to do it. That said, I was doubtful four weeks of SAD was going to do something dramatically bad — or at least, that whatever it did I could undo given time and discipline.

Obviously, I take comfort in having observed the downward trend I had from July ’16 to Nov ’17 in the hopes I’ll recover that drop again. But given just what we have to look at here, the precipitous drop took a year and a half. Could just four weeks of SAD and corresponding weight gain have brought it up so quickly?

One thing is for sure, this data should be very powerful for anyone who likes to “take a break” from their keto diet for the holidays.

For a breakdown of the exact numbers:

Six Months or Four Weeks?

It is true I’m inclined to assume it was the four weeks of the SAD diet that impacted my CIMT the most. Much of the reason for this assumption comes from the fact I had done a number of carb-swap and carb-addition experiments both in the May ’17-November ’17 cycle as well as the November ’17-May ’18 cycle. The one obvious difference between the two being the Weight Gain Experiment and my getting this CIMT right near the end of it.

Nevertheless, it would’ve been better to have gotten the CIMT right before the experiment started in April to confirm this. But to be sure, I didn’t imagine we’d see such a substantial impact! Science!

What Do The Studies Say?

I got a little curious about age-stratified CIMT scores and did some browsing around the interwebs. What follows below are some grabs along with my circling of the November ’17 score and the May ’18 score in contrast.

For reference, I’m Male, 45, and I like long walks on the beach. (Units converted below)

From here:

Or this study:

Or this one:

It seems no matter how you slice it, this was a move from clearly a low-risk category to clearly a high-risk category!

But here’s the kicker… as you can see from the chart above, I originally was in a high-risk category early on into keto, but I precipitously dropped into the low-risk category while following the diet. Richochet.

Can I drop it again as I go back into full keto? Only time will tell.

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22 Comments on "Carotid Artery Update, SAD Diet Edition"

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Joe Kalb

Dave, thank you for doing this work. It is admirable that you are putting your own skin in the game, knowing that you are putting yourself at risk, to openly provide this data for anyone interested.

Remarkable results for four weeks of the Standard American Diet.

Godspeed getting healthier.

Brian Scott Edwards MD

Need to know if chart axis is in mm’s?

Paul T

I’m curious if you think a similar result would obtain with a CAC test. I did a quick check and found an abstract stating that CAC and CIMT correlate well. I’ve heard opinion that CAC is something of a “gold standard” in terms of CVD predictive value. (And I’ve scheduled a CAC for myself). Thanks for all the work you’re doing. I’ve passed it on to siblings in an effort to educate them.

Jamie P
I’m curious about this too. I opted for the CAC as I read in Dr. William Davis’ book, Track Your Plaque, that the the CIMT was not as accurate. As I understand it, the radiation from the CAC is also too high to have done more than about once every 10 years. I just had mine done in March and had total score of 8.83 with left main at 0, LAD at 0, RCA at 0, and LCX at 8.83. Unfortunately, this was my first, so I have no idea if the past 6.5 years of LCHF has improved anything.… Read more »

I’m not sure of that correlation. I have a + CIMT, but a CAC of 1. Wish both of these were part of the standards of care so the data set would be much richer. OTOH, bigPharma, bigMed, bigFood might not like what is found.


I’m curious to know what the margin of error is on a test like this (ie how precise is it in terms of measurement). Would two tests back to back show similar numbers?

Jim Ingram

That’s definitely my question. CMIT is highly dependent on operator technique. Three or four tests in a row might expose this issue, although I’m sure there is a known accepted margin of error.

Personally I’d really like to know LMHR’s on Keto see stability with CIMT or improvement


Dave, I feel like the rate at which you are uncovering interesting things is incredibly fast compared to medical researchers, which is great. But there are problems – for example, it is not even widely accepted that changes in CIMT are clinically significant. Apparently many doctors view it more or less as a static value, which seems pretty odd to me, but what do I know.

So when are you going to get your Silicon Valley friends together to fund a series of massive clinical trials?


My question: How the heck did you even know to get this test? Since Ivor Cummins is all over the CAC test, I’ve decided to get one of those….but I don’t know anyone who knows their CIMT score. (Other than my mother…but she smokes and has known artery problems.)


i do not believe the correlation between CIMT and health of coronary arteries all that strong; and may make sense as some have strokes but not heart attacks and vice versa.
Do you layout the SAD diet u followed somewhere? Thanks.

chris c

Good grief! No wonder they are so reluctant to use this test, or CAC or that matter. Here in the UK an increasing number of patients can no longer even have trigs tested, or reported. Just total “cholesterol” and a ratio. Keep them on the carbs and statins . . .

Chris S

I live in UK – trigs is very easy to get. If you want more then PLAC test is £70. If you want VAP test it is about £300 which includes homocysteine. CRP is free as is vitamin D.

chris c
Depends on circumstances and where you live. Here our nurses can only do the cut down test, it needs a doctor to do the full monty. LDL actually used to be measured rather than calculated until they changed labs which was interesting, it came out about halfway between the Friedwald and Iranian calcs. GP could not authorise CRP or homocysteine, it took a consultant. Yet I can get not only TSH but T4 AND T3 (hyperthyroid), in many places only TSH is available. Getting actual numerical results can also be a problem, nurses don’t give them out, only doctors or… Read more »

Amazing Dave, congratulations, I had not expected this would be so rapid. Proving that keto can lower CIMT and hence CAC/calcification and hence risk of heart disease/myocardial infarction is a really big deal.


Hi Dave,
Great experiment (hope no irreversible effects come fromt it) – quick question: originally you had stated that you had a goal of going up to 205-210 lbs – did you get there? I’m keen to know if, after fat-adaptation, the energy metabolism CICO mechanism is affected (either by increasing output / energy expenditure or via fat storage as would be “expected”).

Best of luck getting back to square one (keto wagon).

Or N
Dear Dave, Thanks for the information! I am trying to improve my CIMT score, and I have a hard time without metrics to track my progress. Your frequent testing and manipulation gives me hope that CIMT could be sensitive enough to try every few months. Do you have a clue what is the minimal interval for a significant result? Also, I wish I had some daily measurement to take that might correlate with CIMT, vascular health, or inflammation in general. Do you have any idea for something I could track to see how my lifestyle is effecting my goals? Thank… Read more »