Monthly Archives: November 2012

More Evidence for Low-Carb Diets

In our book we point out a number of dietary tactics that appear to substantially decrease risk of cardiovascular disease. They include:

  • Optimizing tissue omega-6 to omega-3 balance by minimizing intake of omega-6 fats and eating an oily marine fish like salmon or sardines once a week.
  • Optimizing various micronutrients including vitamins D and K2, choline, magnesium, iodine, and selenium.
  • Reducing carbohydrate intake to the body’s natural level of glucose utilization, about 30% of total calories.

We cited two main sources for the claim that reducing carbohydrate intake reduces risk of cardiovascular disease:

–          The Nurses Health Study found that risk of coronary heart disease went down steadily as dietary carbohydrates were reduced and replaced by fat. Those eating a 59% carb diet were 42% more likely to have heart attacks than those eating a 37% carb diet. [1]

–          Replacing dietary carbohydrate with saturated or monounsaturated fat raises HDL and lowers triglycerides, changes that are associated with low rates of cardiovascular disease. Blood lipids are optimized when carb intake drops to 30% of energy or less. [2]

I think this is pretty strong evidence. It is not completely bulletproof, because associations don’t prove causation and improving risk factors doesn’t necessarily improve disease risk; but, combined with supportive evidence from cellular biology and clear evidence that evolutionary selection favors a carbohydrate intake around 30%, I consider it convincing.

However, it’s always good to have more evidence; and two new studies provide some. One directly relates utilization of carbohydrates for energy to atherosclerosis, and the other conducted a 12-month clinical trial of a carbohydrate restricted diet.

Carbohydrate Utilization is Associated With Atherosclerosis

Via Stephan Guyenet comes a study that directly links carbohydrate metabolism to atherosclerosis: “Metabolic fuel utilization and subclinical atherosclerosis in overweight/obese subjects.” [3]

The study used intima-media thickness in the carotid artery, which serves the head and neck, as a measure of atherosclerosis. As Wikipedia notes,

Since the 1990s, both small clinical and several larger scale pharmaceutical trials have used carotid artery IMT as a surrogate endpoint for evaluating the regression and/or progression of atherosclerotic cardiovascular disease. Many studies have documented the relation between the carotid IMT and the presence and severity of atherosclerosis.

To assess metabolism it measured the “respiratory quotient” or RQ. RQ is the ratio of carbon dioxide (CO2) generated in the body to oxygen (O2) consumed in the body.

RQ indicates which fuels are being burned for energy in the body. When carbohydrates are burned, the reaction involves carbon exclusively, so for every O2 molecule consumed there is a CO2 molecule created. This makes the RQ 1.0 when carbohydrates are burned.

Fats, however, donate both carbon and hydrogen, and the hydrogens react with oxygen to make water (H2O). So some of the oxygen consumed when fats are burned goes into water, not carbon dioxide, and the RQ when fats are burned is about 0.7. Ketones also have an RQ around 0.7.

Amino acids from protein have variable amounts of hydrogen and carbon, some amino acids are ketogenic and some are glucogenic, and so the RQ of protein depends on its amino acid mix. Typically RQ from different types of food protein is between 0.8 and 0.9.

However, most people eat a fairly consistent amount of protein, around 15% of energy, so the variable that generally determines RQ in practice is the ratio of carbs to fat in the diet. Higher RQ indicates a higher-carb diet.

Another study had previously shown that calorie restriction, which also reduces RQ by replacing dietary carbohydrate with fat released from adipose tissue, reduces the thickness of the carotid intima-media. [4] This study was the first testing whether the RQ-CIMT relationship holds also in subjects not known to be restricting calories.

The study found that indeed it does: the lower RQ, the less atherosclerosis the subjects had. Unfortunately they don’t present data in a visually useful way (a scatter plot of RQ vs CIMT would have been helpful); here is what they do show:

RQ was better than waist circumference or BMI at predicting degree of atherosclerosis. Only age was a stronger predictor of atherosclerosis than RQ.

RQ predicted atherosclerosis equally well in subjects with and without obesity. This tells us two things:

  1. It supports the idea that it was habitual diet rather than recent calorie restriction (which decreases RQ by replacing food-sourced calories with fat from adipose tissue) that generated low RQ and low CIMT.
  2. As the authors say, it indicates “the main role of metabolic factors rather than BMI” in generating atherosclerosis – metabolic factors meaning burning glucose for energy rather than fat.

It is also supporting evidence for one of the more controversial lines of our book, that “mitochondria prefer fat.”

One caution: Most of the subjects in this study were eating diets that were around 50% to 55% carbohydrate, so the study was testing whether it’s better to eat a little above or below this carb intake. It tells us, I think, that a 45% carb diet is healthier than a diet with more than 50% carbs. It doesn’t tell us what carb intake is optimal.

The Clinical Trial

In a trial lasting 12 months, restricting carbohydrates to 600 to 850 calories per day – that is, about the 30% of energy that we recommend – in the context of a slightly hypocaloric diet improved cardiovascular risk factors. [5]

Overweight and obese subjects in the trial lost 2.8 kg (6 pounds) over the year-long trial, so it couldn’t have been severely calorie restricted. Changes in other risk factors:

–          Blood pressure dropped from 121/79 to 112/72;

–          Fasting blood glucose dropped from prediabetic 106 mg/dl to normal 96 mg/dl;

–          Lipids improved, with triglycerides decreasing from 217 to 155 mg/dl and HDL increasing from 39 to 45 mg/dl.

They conclude:

The results of this study indicate that a moderately restricted calorie and carbohydrate diet has a positive effect on body weight loss and improves the elements of metabolic syndrome in patients with overweight or obesity and prediabetes. These results underscore the need to provide dietary recommendations focusing on calorie and carbohydrate restrictions … Our results are in agreement with reports produced by other authors who also assessed a carbohydrate-reduced diet …


A number of simple dietary and nutritional changes appear to reduce the risk of atherosclerosis and cardiovascular disease generally. One of them is reducing carbohydrate intake.

I believe the optimum carbohydrate intake is around 30% of energy. Many studies generate clear evidence of benefits as carbs are brought down into the range of 20% to 30% of energy, especially in metabolic disorders like metabolic syndrome, diabetes, and obesity. It’s good to see that evidence from other diseases, such as CVD, also supports the same carb intake.

Because most people’s diets are flawed in so many different ways, and fixing an individual factor is often associated with a reduction in CVD risk of 40% to 70%, it’s possible that we could reduce CVD risk by 90% or more by implementing all of the dietary optimizations described in our book.

It’s well worth pursuing all these little optimizations!


[1] Halton TL et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women.  N Engl J Med. 2006 Nov 9;355(19):1991-2002.

[2] Krauss RM. Atherogenic lipoprotein phenotype and diet-gene interactions. J Nutr. 2001 Feb;131(2):340S-3S.

[3] Montalcini T et al. Metabolic fuel utilization and subclinical atherosclerosis in overweight/obese subjects. Endocrine. 2012 Nov 28. [Epub ahead of print]

[4] Iannuzzi A et al. Comparison of two diets of varying glycemic index on carotid subclinical atherosclerosis in obese children. Heart Vessels. 2009 Nov;24(6):419-24.

[5] Velázquez-López L et al. Low calorie and carbohydrate diet: to improve the cardiovascular risk indicators in overweight or obese adults with prediabetes. Endocrine. 2012 Sep 1. [Epub ahead of print]

Happy Thanksgiving Everyone!

St Paul left good advice for science bloggers when he advised, “Prove all things; hold fast that which is good.” But he left an even better motto for health bloggers: “Rejoice always; in everything give thanks.”

So let us recall all that is good, hold fast to it, rejoice in it, and give thanks for it. May your Thanksgiving Day be blessed!

Here is Mary Chapin Carpenter:

Johnny Cash:

And for history buffs, City upon a Hill (John Winthrop, 1630):

Now the onely way to avoyde this shipwracke and to provide for our posterity is to followe the Counsell of Micah, to doe Justly, to love mercy, to walke humbly with our God, wee must be knitt together in this worke as one man, wee must entertaine each other in brotherly Affeccion …

[F]or wee must Consider that wee shall be as a Citty upon a Hill, the eies of all people are uppon us; soe that if wee shall deale falsely with our god in this worke wee have undertaken and soe cause him to withdrawe his present help from us, wee shall be made a story and a byword through the world … And to shutt upp this discourse with that exhortacion of Moses that faithfull servant of the Lord in his last farewell to Israell: Beloved there is now sett before us life, and good, deathe and evill in that wee are Commaunded this day to love the Lord our God, and to love one another to walke in his wayes and to keepe his Commaundements and his Ordinance, and his lawes, and the Articles of our Covenant with him that wee may live and be multiplyed, and that the Lord our God may blesse us in the land whether wee goe to possesse it: But if our heartes shall turne away soe that wee will not obey, but shall be seduced and worshipp other Gods our pleasures, and proffitts, and serve them, it is propounded unto us this day, wee shall surely perishe out of the good Land whether wee passe over this vast Sea to possesse it;

Therefore lett us choose life,
that wee, and our Seede,
may live; by obeyeing his
voyce, and cleaveing to him,
for hee is our life, and
our prosperity.

Around the Web: Preparing to Give Thanks Edition

I’ve just touched a finished copy of our new book for the first time: it is gorgeous! This picture is a poor substitute, but here’s a view of the cover.

[1] Cute animals:

Via Yves Smith.

[2] Semi-cute animal: K-pop is so hot, even the Oregon Duck can’t stop dancing Gangnam style:

[3] Interesting Items:

Peter Dobromylskyj of Hyperlipid has been looking at how different dietary fatty acids help or hinder mitochondrial control of cellular metabolism. He has two intriguing posts today:

–          In the first, he proposes that saturated fats make long fasts more tolerable by enabling better control of energy utilization; polyunsaturated fats make long fasts intolerable and trigger hypoglycemia, stimulating appetite. This would be the second known pathway by which omega-6 fats upregulate appetite: omega-6 fats can also degrade to endocannibinoids which stimulate eating.

–          In the second, he suggests that an omega-6 rich ketogenic diet would promote diabetes by creating conditions of cellular energy excess. Saturated fats protect against that scenario. Perhaps Peter and CarbSane can agree: There is such a thing as “nutty ketosis”!

Meanwhile, Jimmy Moore is doing well on nutritional ketosis, but Neely Quinn of Paleo Plan had trouble.

CarbSane finds another zero-carb danger: thiamin deficiency neuropathy.

Mark’s Daily Apple has a 204-page forum thread on the “Potato Diet.” Tatertot asked me what I thought of a potato-only diet as a weight loss tactic, and I gave my thoughts here. I might add: Safe starches have come a long way, if the hot new Paleo/Primal weight loss fad is 100% safe starch!

Dr Weil is behind the times; he thinks Paleo doesn’t include starches.

Kaleigh Laventure, The Paleo Angel, talks to Abel James about the trouble she had on Leangains. It seems like the junk-food binging part of the protocol was a big problem.

Hey, what does Stephan Guyenet have against bacon egg doughnut burgers?

If you want a starch-free breakfast, Laura at This Felicitous Life has a recipe: banana and egg pancakes. She writes:

Well, we’re starting our fifth week here of the Perfect Health Diet.  Pat is down about 8 pounds and has noted that he now has to wear a belt to keep his pants from sliding down.  He’s been overheard marveling, “I can’t believe I’m losing weight by eating steak and nuts and cheese and butter!”  So far I’ve refrained from socking him in the schnozz.

I’m stuck at starting weight – 1lb.


Razib Khan subscribes to a rather unusual version of Paleo.

Sean at PragueStepChild has good parenting advice.

Ray Medina looks at foods that can affect sleep.

Stefani Ruper has a manual for overcoming PCOS. Sol Orwell offers supplement advice at

Prof Dr Andro reports that frying creates peroxides and destroys vitamin E; and that the more fat toddlers eat at age 2, the less fat is around their waist at age 20.

Is fish oil a toxin whose benefits come through hormesis?

Chris Kresser reports another reason we’re undernourished:  we eat foods long after harvest.

David Despain has plenty to say about the diet of lemurs.

[4] Not the Weekly Video: Primal Chef has a cookoff between Sarah Fragoso of Everyday Paleo and Cindy Anschutz of Cindy’s Table:

[5] Reader Results: Our last roundup of reader results was two months ago, and a number of reports have rolled in since.

Conor says:

First of all – thank you. I started on the PHD a couple of years ago after buying one of the earliest copies of your book (you were kind enough to ship it to New Zealand). I’ve found it extremely successful, with a couple of nagging issues (rosacea for example) resolving totally. I also noticed greatly increased energy.

Evan had the high LDL on Paleo problem and after following our suggestions – safe starches and mineral supplements – says, “WOW, Feeling great in just 3 weeks.”

Laura has also had good results.

Jonathan cured his restless leg syndrome:

Hi Paul, just wanted to let you know that after approximately 2 months on PHD and taking the recommended supplements, my restless leg syndrome has completely disappeared. I was a bit hesitant at first to believe it could be true, but it’s been a few weeks now so I can say it’s officially gone. This is something I remember having since I was a young child, maybe 6 or 7 so it’s pretty neat to resolve the issue through diet.

An email:

Incredible book! The most fascinating book I’ve ever read. It has helped me cure all my health issues and I can’t thank you enough for writing this book. I pass it on to everyone I meet. This book can definitely put chronic diseases in the past.

Johnny reports PHD is working well for weight loss:

Hi Paul,

At 235lb I started a low carb diet and went to 198 but my loss stalled.

I changed to the Perfect Health Diet: Weight Loss Version, consuming at least 600 daily calories combined protein and carbs, with overall calories of 1,200-1,500 per day.

My weight loss restarted, although at about 1 lb. per week, and I’m now at 188.

Mike C had a similar experience:

Hey Paul, Just want to thank you for taking the time to research and write a book that makes sense in every aspect. I am a 44 year old male who started this journey at 405lbs with LC/Atkins but after losing the inital water weight I then proceeded to lose and gain the same 3 pounds over and over again during the next 4 months. I was strict, ate no more than 20 net carbs per day and felt ok, but no weight loss….

Eating by PHD rules, the weight has begun to come off again!! I don’t count anything, but always ensure to eat by the guidelines you suggest and I find I eat less calories and feel full longer naturally and the “IF” that I really did not want to do as part of the plan has come naturally and not eating till noon from the night before is really no problem. I have dropped weight and a few pants sizes since started this plan and more importantly I am really enjoying my food again. Adding 300 to 400 calories in potatoes or rice each day has really opened up the dishes I can make again. I feel better, less hungry and more satisfied eating PHD and real food. French fires made in grass fed tallow are my new health food and we have them 3 or 4 times a week! I wanted a way I could eat for life and I found it. Thanks again and I look forward to the new version of the book!

FYI: I would guestimate I eat around 2300 calories a day. I am losing 2 pounds per week and am down to 372lbs.

Paloma reports that intermittent fasting cured her insomnia:

Thanks for this post! I have been doing this for a week now and it works!

I was desperate because I wasn’t able to get asleep… I have two small kids so imagine how tired I was! But I was doing it all wrong. Now I skip breakfast, have an early lunch, some merienda at 17 h and dinner at 20:30. Then a cold bath at 22h and get asleep in 5 minutes! Thanks!

Linda Wyatt has eliminated her migraines:

I started a ketogenic diet for other reasons, but the first and most obvious change was that my migraines stopped. I had no idea this would be a possible benefit, but now, it is my primary motivation for staying on the diet. I have no interest whatsoever in going back to frequent, debilitating, migraines.

Allison is recovering from hypothyroidism:

Hi Paul,

You may remember I commented about a month or so ago that I’d started following PHD after a year of struggling with debilitating hypothyroidism (despite supplementation with compounded thyroid and cytomel), along with low testosterone, low DHEA, underfunctioning adrenals, and a vitamin D deficiency. Less than two months ago, I was unable to drive, and was having trouble walking due to the fatigue and trouble with muscle coordination.

The results of my most recent blood work are in, and there are great improvements: my vitamin D levels have returned to optimal levels, my DHEA is normal, my testosterone has increased (although its not at a normal level yet), and my free T3 has increased to 3.1. Before, it was so low it wasn’t even on the chart and only my total t3 could be reported (which, obviously, was mostly reverse t3). My adrenals have yet to show any improvement.

I still have a way to go, but what a huge improvement! Most days, I feel pretty good. I’ll keep at it.

Dave Baird was one of those who had a brief weight gain before losing weight on PHD:

When I first started following the Perfect Health Diet I gained 1.5 kilos – this has since been lost again and I’m consistently losing about a kilo per week.

Jack Cameron improved his cardiovascular health:

After reading “Perfect Health Diet” I increased my intake of saturated fats and reduced intake of grains and legumes. After a few months on the improved diet I had an echocardiogram and a VAP test. The echo showed that my ejection fraction had increased from 65 two years earlier to 75 which is about as good as it gets. The VAP test showed by TG dropped from 66 to 60 and HDL increased from 80 to 88. Apo B dropped from 98 to 90. Blood pressure is now 110 over 60.

Ana Cheeseman noticed something odd – a new eye color:

I have been following your diet for the past months and I have been feeling amazing!!! My acne has cleared up, my periods are normal, I have lost weight, everything’s been great!! What I have noticed however is a change in my eye colour. My eyes used to be dark brown but now they are hazel.

Cindy Rosenberg left a nice comment on Facebook:

this way of eating is changing my body and my life, and that of many of my patients. thank you so much for your wisdom and guidance. so so grateful

Nora is also happy:

I love PHD. It makes me feel great, I am always satisfied at the end of a meal. I don’t have to eat as much anymore because I don’t have cravings.

Finally, a case of recovery from tortilla poisoning:

Thank you so much for writing the Perfect Health Diet book!

I have lost 20 pounds in six months by simply reducing the amount of tortillas I was eating. I used to eat up to 15 tortillas a day. Now I eat about five for the whole week. Like you guys said; the dose is the poison!

[6] Shou-Ching’s Photo Art:

[7] Video of the week: The Hubble Ultra Deep Field in 3D:

via Jennifer Fulwiler.

Did the Health Environment Stop Getting Better in 1950?

That’s the rather provocative idea set forth in our latest post at Psychology Today, “The Rise — and Fall? – of American Health.”

We look at data on life expectancy and disease rates and ponder whether the era of improving public health may be ending. Here’s one of the key figures:

This is the first post in a series looking at the major factors in health and longevity, so if you’re interested in that topic, check out our Psychology Today post!

About Our Two Blogs

I have decided that I’m going to post distinct content on our two blogs. There will be no duplicate posts, though I will post a teaser here when I put something up on Psychology Today.

This blog will primarily be about personal health – how can each of us achieve the best possible health. It will continue to have research and speculative science in which we explore the causes of disease and tactics for becoming healthier, food posts, Around the Web posts, and in general the same type of content it’s always had. The audience we’ll try to speak to will be the Primal/Paleo/PHD/Ancestral Health community that most of us know and love.

Our Psychology Today blog will be addressed to people outside the Ancestral Health community. It will try to offer an ancestral health perspective on issues and controversies of widespread interest. We’ll be advocating an ancestral diet and lifestyle, but what we advocate will rarely be PHD-specific and most posts will seek to engage people who are not in the Ancestral Health community on topics of general public interest. We hope that this approach will help draw new people into our (to quote Mark Sisson) “new (yet ancestral), radical (yet reasonable) movement.”