Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
18 Jun

Is It Time to Retire the Low-Carb Diet “Fad”?

This is another special guest post from our favorite study-dismantler, Denise Minger. Read all of her previous Mark’s Daily Apple articles here, here, here, here and here, and pay her website a visit. Thanks, Denise, for clearing up the confusion once again!

Sweden is a land of many wonders – most of which put the USA to shame. They’ve got fjords, ABBA, and caviar in a tube. And while Americans get arrested for things like DUIs and stealing socks from Walmart, Swedes get arrested for the more admirable feat of smuggling butter.

Such a delicious felony doesn’t reflect a life of crime so much as a life of fat – the edible kind. For nearly a decade, Sweden has been the unofficial headquarters of the Low Carb High Fat (LCHF) movement, churning out an unprecedented number of lipid lovers. In 2011, a whopping 25% of Sweden’s population was trying to eat more fat and curb their carbohydrate intake, with 5% of Swedes identifying as hardcore LCHF adherents. And those numbers only seem to be growing.

But a new study claims to cast doubt on the safety of Sweden’s fatward trend. In a paper published in Nutrition Journal last week (PDF available here), researchers linked the Swedish low-carb boom to rising cholesterol levels, increased heart disease risk, and failure to maintain long-term weight loss. A cascade of predictable headlines ensued, ranging from “Atkins diet found to be bad for the heart” to the brazen “Time to retire the low-carb diet fad.” The latter article – a well-circulated piece from The Atlantic – gave low-carb fans a particularly snarky flogging:

Low carbohydrate evangelists will almost certainly attack today’s announcement – and perhaps this post – with biblical fury. They’ll make their usual claim: that this is yet another conspiracy of scientists who just don’t get it, scientists who don’t understand nutrition, scientists who somehow made it through their PhD’s and MD’s without knowing the first thing about how the human body works. But let’s face it – most of us know in our hearts that eschewing a breakfast of whole grains and fruit crowned with a dab of yogurt for a greasy pile of sausage, bacon, and eggs is not the road to health.

Ouch! Time to whip out the granola and Yoplait?

If something seems fishy about this study, it’s not just the lutfisk: as usual, there’s more going on (or in this case, less going on) than the alarmist media would suggest. Here’s the real scoop.

No Low Carb, No Heart Disease

First and foremost, this study has nothing to do with low carbers, or even heart disease: it’s an observational study of Swedes Not Further Specified (SNFS). Researchers pulled 25 years’ worth of data from 140,000 folks in the North Sweden Diet Database, averaged everyone’s food intake, averaged everyone’s total cholesterol, and made some pretty graphs.

The findings? Sweden’s fat consumption (as a percent of total energy) dropped between 1986 and 1991, held steady until about 2004, and then started rising; the inverse happened with carbs:

(In those early years, fat kerplunked due to the Vasterbotten Intervention Programme – a project launched in the mid ‘80s to encourage more physical activity, scoot Swedes towards a low-fat Mediterranean diet, improve food labeling, and hopefully knock heart disease off its tyrannous throne.)

And like an ant frantically evading the smoosh of a human thumb, average body mass index skittered wherever the heck it wanted (usually up):

And average total cholesterol – not among low carbers, but among north Sweden’s general populationfollowed a roller-coaster-esque trajectory of its own. It plummeted between 1986 and 1992, crept back up until 1994, rolled downhill again until 2000, stabilized between 2002 and 2008, and then began yet another upward jog until the study ended. A visual for your viewing pleasure:

That’s it. No distinction between HDL and LDL, no reported triglycerides, and – most notably – no mention of how diet or cholesterol changes corresponded with actual heart disease rates. In fact, there’s nary a morbidity or mortality statistic to be found in the whole paper.

So how did the doom-and-gloom warnings about low carbing enter the scene?

Simple: the researchers think Sweden’s recent cholesterol hike might be a result of the LCHF boom – although the design of this study, with dieters of all persuasions stirred together in a giant pot of data-soup, makes it impossible to tell if that’s actually the case. Although the media apparently didn’t get the memo, the researchers even stated in their paper that “our study design does not allow a causal evaluation of the relationship between the increased fat intake since 2004 and the increased cholesterol values after 2007.” Likewise, the media thinks Sweden’s ever-increasing BMI, despite being an average of the general population, means that low-carb adherents fail to maintain their weight loss. (Yeah, I’m scratching my head over that logic too.)

Although it’s possible that saturated-fat-loving, low-carbing Swedes singlehandedly raised the nation’s average cholesterol in 2008, this seems iffy for a few reasons. For one, fat intake and blood cholesterol were hardly mirroring each other for the study’s previous 22 years: cholesterol levels continued to drop even when fat intake remained steady (though this could also be confounded by use of statins and ratios of specific fatty acids). Even more suspiciously, there was a four-to-six-year lag between the rise in fat consumption and the 2008 cholesterol jump – implying that Sweden’s fat-feasting took half a decade to affect blood values. (Usually cholesterol reflects diet changes in a matter of weeks.) And although this particular study tells us nada beyond “total cholesterol,” another paper published just a few months ago – drawing from the same pool of data – shows that after 2008, north Sweden’s triglycerides were frolicking uphill with cholesterol:

If that graph convinces anyone that the Low Carb High Fat movement is spiking triglycerides, I’ve got some oceanfront property in Arizona to sell ‘em, too: the evidence is pretty consistent that low carbing makes triglycerides sink. It seems more likely that other factors are lurking behind Sweden’s shifting blood lipid patterns, especially during the past few years.

Lo and behold, the fine print of our study-du-jour suggests the same. According to the researchers, foods associated with a high fat intake in Sweden were not just the predictable oils and meats, but also pizza, French fries, potato chips, corn chips, cheese-flavored puffed products, and popcorn, as well as “fats used for spreading on bread.” Unless Sweden has a very different definition of “low carb” than the rest of the world, it sounds like their fat intake isn’t coming solely from LCHF-approved fare, but from what most of us affectionately refer to as bona fide junk.

Even when it comes to foods directly associated with high cholesterol, Sweden’s low-carb movement still can’t shoulder all the blame. According to a supplementary table kindly included with the paper (available as a Word document here), boiled potatoes and coffee made bigger statistical contributions to blood cholesterol than saturated fat did! Other foods associated with high cholesterol included not just high-fat foods, but also low-carb no-gos like sweet buns, crisp bread, white bread, and sweet fruit soups.

Dairied Alive

Although this study doesn’t reveal anything very useful about what food does to us (particularly where fat is concerned), fear not: the diet-disease data for northern Sweden is a many splendored thing, and other studies have mined it with much more fruitful results. Or in some cases, milkful.

In 2010, the American Journal of Clinical Nutrition published a paper looking directly at dairy fat and myocardial infarction among some of the same northern Swedes used in last week’s study. The results? Women with high intakes of dairy fat – confirmed both by food-frequency questionnaires and ruminant-milk-fat biomarkers – were less likely to suffer from a first heart attack than their milk-minimizing counterparts. (Cheese and fermented dairy products looked particularly heart-protective.) And just in case you think that one was a fluke, a 2004 study examining the same Swedish population found dairy fat to be negatively associated with cardiovascular risk factors, with zero indication that full-fat milk products contribute to heart attacks. Want more? Yet another study (PDF), again based on those fat-loving northern Swedes, found dairy fat to be beautifully protective against strokes – especially in women.

So much for all that “artery clogging” hoopla!

Are Low Carbers in the Clear?

It’s a mystery why our current study tried to glean anything about low-carb diets from such tight-lipped data – especially since it’d be easy enough to actually untangle those low carbers from the rest of the population and follow them, up close and personal, like the stalkers we all secretly yearn to be. In fact, another north Sweden study published in February attempted that very feat (sans creepiness), and failed to find any increased mortality among the folks it deemed “low carb.” (Unfortunately, that study also used an invariably terrible diet-score design, but that’s a story for another day.)

As for Sweden’s recent cholesterol uppage? Without more detailed data and a look-see at disease rates, it’s virtually meaningless. But even if there’s no legitimate evidence dooming Swedish low carbers to an early grave, it’s possible that the LCHF movement is having some unhappy consequences in the Land of the Midnight Sun. The health climate there is clearly whipping fat-phobia into remission – which, despite the admirable triumph over bad science, could also breed a new species of half-hearted dieters like Low Carb Weekend Warriors, Low Carb As Long as There’s Not a Cookie in Front of Me, and Why Don’t I Just Put Butter on Everything Edible and Buy New Pants When They Get Too Tight. Folks who jump on the “high fat” bandwagon while still living in high-carb land may indeed find themselves gaining weight and frightening their doctors with ominous lipid panels. Whether or not this is happening in Sweden right now remains to be known, but it is a possibility.

Personally, though, I have other theories:

I’m not saying correlation equals causation. I’m just saying maybe we should think about switching to Google Plus.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. There is a new, similar study. Would be great to get comments on this one as well:

    RobB wrote on June 29th, 2012
  2. Great article! I just wrote a blog last week about being a skeptic for these exact reasons. Thank you for doing the research and putting it all out there!

    Angela @ The Chicken Scoop wrote on June 29th, 2012
  3. The graph are impressive. And convincing.

    tim wrote on July 14th, 2012
  4. What annoys me is that Mark eats COFEE with SUGAR in the morning (not paleo), eats potatoes, chocolate and wine (not paleo) and drinks his protein shake (not paleo), but STILL talks about this lifestyle as if he is following it.

    Liz wrote on September 22nd, 2012
  5. A New and Very Important Statement from the American Heart Association.
    If all the contradictory information about what you should or should not eat to avoid heart disease has you wondering what you should do to guard your health, a statement released by the American Medical Association October 12, 1962, is very important to you.

    The statement is a result of the deliberations of America’s top nutrition and health authorities who have analyzed carefully all of the information available at this time.

    Before you consider any changes in your diet, read this statement, the full text of which follows:



    The food fad the AMA was citing was the low-fat, low-cholesterol diet.

    Ed wrote on September 26th, 2012
  6. excellent! but just have to say, sweden doesnt have fjords, norway do. im married with a norwegian girl thats way i know. but still, a lot of good information!!!

    Federico wrote on November 13th, 2012
  7. Does anyone know what the difference between the LCHF diet and The Liberation Diet is?

    Missy wrote on March 26th, 2013
  8. Clearly Obama increased Swedes’ cholesterol levels.

    Evie wrote on June 12th, 2013
  9. Nice to know my chowing through 1/2 pound of cheese a week and two pints of full fat yoghurt when low carbing won’t mess with me.

    I’m a ‘fat metabolizer’. Feel great on low carb, boundless energy, no hunger etc. Makes me laugh my ass off when people tell me it’s unhealthy while eating white bread and putting sugar in their coffee.

    I have noticed a tendency to leap on examples from high carb diets and apply them to low carb, and to include trans fats in ‘fats’ in studies. They aren’t natural, we didn’t evolve to eat them. I’m sure it’s the inclusion of crappy margarine and similar fats from previous studies that made fats read as ‘bad’.

    Heretique wrote on July 17th, 2013
  10. Having done a little digging into this study, I thinks it’s a safe bet that they didn’t bother to separate processed meats like sausage, ham and bacon from the other protein sources. The Swedes are well known for their love of bacon and ham, and processed meats are well known as causal factors in heart disease and cancer due to the crap used to preserve them.

    I’ve sen a similar thing happen in pro vegetarian studies where processed meat is shunted in with all other animal protein to ‘prove’ meat causes cancer/ whatever. However, some educated digging shows that white meat has zero association with CVD and cancer and fish appears to protect against both. One can infer from this that the apparent carcinogen seems to specifically be processed red meat.

    It’s the same thing that happened in the older dietary fat studies where trans fats were lumped in all the others.

    Mathilda wrote on July 24th, 2013
    • Thank you for this comment. I get so frustrated when people (especially scientist and physicians) try and present data like that showing that meat consumption is associated with cancer and heart disease.

      Steven wrote on October 18th, 2013
  11. If you look at the dietary approaches to extending lifespan and more importantly, healthspan, caloric restriction is by far the most potent intervention that has been shown to work in every organism studied. Recent data on monkeys is somewhat conflicting but is really difficult to execute given their long lifespans.

    Then, if you look at the gene expression array data, serum biomarker data, cancer incidence rates then you will find that restriction of dietary carbohydrates most closely resembles caloric restriction and possibly exceeds the beneficial effect of calorie restriction.

    Perhaps the most compelling argument in support of carb restriction being far superior for health is the lowering of insulin/glucose spikes and perhaps even basal insulin/glucose levels.

    Insulin and Insulin-like growth factor IGF-1 have been shown to play an important role in driving aging.

    “Contribution to aging

    It is now widely accepted that signaling through the insulin/IGF-1-like receptor pathway is a significant contributor to the biological aging process in many organisms. This avenue of research first achieved prominence with the work of Cynthia Kenyon, who showed that mutations in the daf-2 gene double the lifespan of the roundworm, C. elegans.[11] Daf-2 encodes the worm’s unified insulin/IGF-1-like receptor. Despite the impact of IGF1-like on C. elegans longevity, direct application to mammalian aging is not as clear as mammals do not form dauer like developmental stages.

    Insulin/IGF-1-like signaling is conserved from worms to humans. In vitro experiments show that mutations that reduce insulin/IGF-1 signaling have been shown to decelerate the degenerative aging process and extend lifespan in a wide range of organisms, including Drosophila melanogaster, mice,[12] and possibly humans.[13][14][15][16] Reduced IGF-1 signaling is also thought to contribute to the “anti-aging” effects of Calorie restriction.[17] ”

    I’m not trying to say that a diet based on heavily processed meats (which are full of nitrite preservatives which are positively associated with cardio vascular disease.

    A low carb diet does not have to be high in red meat. In fact there are low carb vegetarian diet, however they are far more restrictive. There are plenty of low carb vegetables and nuts and even some fruit that can make up a significant part of your diet.

    A few last comments
    1, the argument that saturated fat is being harmful is really only applicable to people eating a high carb diet. A low carb diet induces and very unique metabolic state that may even benefit from an increase in saturated fat intake.

    2, ketone bodies, which are produced on a low carb diet to feed the brain with the lower glucose availability have been shown to be beneficial in most neurodegenerative diseases and even after a traumatic brain injury or stroke.

    3. Dietary carbohydrates are the only macro \-nutrient that we can absolutely live without. I’m sure many people have heard of “Essential Amino Acids” which are protein building blocks that we must get in our diet since we can not make them ourselves. It is not as well known that there are also “Essential Fatty Acids (essential fats)” that we must take in through our diet. However, there are NO “Essentail Carbohydrates”, that’s just something to think about.

    Steven wrote on October 18th, 2013
  12. Cholesterol and heart disease are not linked as strongly as everyone makes out. The original study was flawed, the scientist eliminated the majority of countries from his study to give cholesterol and heart disease perfect correlation, using only 6 countries in the end when he originally studied over 20. After being featured on Time Magazine, he then became a hero with his terrible science. High fat diets are good, and grains/high carb consumption is bad. Sugar is what is driving the health epidemics we are currently having. A ketogenic diet has been used for a long time as a treatment for certain ailments and there are even studies suggesting that ketogenic diets hinder the development and spread of cancer.

    Dan wrote on October 29th, 2013
  13. I just wanted to add our family’s story to the low carb success list. We all went on the GAPS diet about 10 months ago. My son has some issues we thought might be helped by it, and as he’s only 7, it was too hard to have him watch us at a ‘normal’ diet while he was on such a strict one – so we all got on the diet together. We all went through the adjustment period pretty quickly, but the most drastic improvement was for my husband. He lost 12kg in the first month, and to date has lost about 26 kg (about 57 pounds). He ate waaaaay too many processed and quick carbs, and cutting them has made a huge difference not only to his weight, but also to his health, energy levels, and clarity of thought….not to mention his sleep apnoea is all but gone. I found that 3 months in, I was so sluggish and tired, I decided to reintroduce some carbs, and boy what a difference!! Since I had no health issues to speak of before the diet, I went back to my usual eating patterns (which sadly does include some junk, though not much). Low carb is a great idea and works well for many, but it is good to listen to your own body and know when it’s telling you that you are lacking something.

    My son, until now has done very well on the diet, though we are seeing he is now constantly ‘pecking’ where initially the food was satisfying and he wasn’t asking for snacks between meals. As a result we are going to reintroduce a small amount of starchy (but unprocessed) carbs every couple of days to see if that helps. He is eating fruits, but they aren’t enough. He is after all our son, so he’s bound to have some of both our genetic traits. He may need that little more carb input as I did. In any case, he is still going to be low carb in comparison to the standard western diet. The best way to know is try it for the individual, we aren’t all clones and variations are needed. Listening to our body is key

    Vera wrote on January 24th, 2014
  14. I have Heterozygous Familial Hypercholesterolemia. I am 58 for the first time in my entire life (ON statins and fibrates included) my cholesterol was 13 and on the pills 8.8 always. No lower. On LCHF it very very quickly went down to 6. Something very strange happened here. I will stay on it forever – I think it’s a lifeliine for me. The blood results told me so.

    Chloe wrote on May 4th, 2014
  15. My great uncle has always been a healthy and strong person. About 15 years ago, my great aunt told me that doctors said nonsense about how many eggs a week we should eat, because “he [my great uncle] has been eating two fried eggs for breakfast for all his life, and look how strong he is…”. Curiously, some days ago I watched a very old woman (about 110 years old) on TV saying that one of her secrets was eating 2 eggs everyday.

    José wrote on December 16th, 2014

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