The Definitive Guide to Conventional Wisdom

Every story needs a villain, and every protagonist needs an antagonist. Here at Mark’s Daily Apple, my regular nemesis is none other than Conventional Wisdom.

But first, let me qualify that statement. Conventional Wisdom isn’t necessarily evil. Take the current medical position on smoking. It seems like common sense to us now that inhaling superheated carcinogenic vapor on a regular basis leads to health issues, but fifty years ago, doctors swore up and down that it wasn’t harmful. They’d light up while taking your temperature, and it was common for pregnant women to enjoy a nice smoke. That was the CW regarding smoking (though I wonder what kind of moneyed interests were behind that one) for years. Eventually, the lung cancer-smoking link became undeniable, and scientists now unanimously agree that smoking is bad for your health. It took them awhile, but they did get it right, and Conventional Wisdom shifted to acknowledge this “new” reality.

That’s rare, however.

In most cases, CW is a lumbering beast: slow to move, but difficult to alter course once its big bullish head is set on moving in a certain direction. It’s the pigheaded, stubborn curmudgeon yelling at those darn kids to get off his lawn. It’s loud, pervasive, and impossible to ignore – and avoid. Oftentimes, entire careers are staked on maintaining its veracity. When that veracity is challenged, either by critics or by experiment, the challenger is often silenced. No, I’m not talking about some conspiracy theory wherein a rival scientist is snuffed out by a cabal of evil scientists. Rather, it’s that a conforming chorus of assent can be mobilized to drown out even the most rigorously defended thesis, just as long as Conventional Wisdom is at stake. The simple fact that faulty Conventional Wisdom – especially nutritional – is mostly supported by not malevolent, but altruistic and good-intentioned people is what makes it so difficult to defeat. Scientists, nutritionists, and doctors are generally convinced that the CW they support and defend is in the best interest of the population. These aren’t evil geniuses; these are good people operating from a fundamentally flawed stance.

Such a fundamentally flawed stance forms the basis for the nutritional CW that we all know and despise: the dietary fat-heart disease link. It started with Ancel Keys’ 7 Country Study, in which he examined heart disease rates in dozens of countries looking for support of his hypothesis that saturated fat intake correlated positively with heart disease mortality. He was able to put together a group of 7 countries that fit the bill – but only after discounting and excluding data points from the 14 other nations that showed little to no correlation! Keys set out to prove a previously-held position and, as is so often the case, he managed to focus only on the evidence that supported it.

Still, even the most inert, seemingly immovable consensus can change if faced with a perfect storm of insurmountable evidence, financial motivation, and unflappable criticism. The money angle is the toughest nut to crack, of course, but it’s our responsibility – as conscious skeptics of all things Conventional – to utilize the evidence and level the criticism on those who deserve it. Good intentions aside, what’s important is getting good health information out there and challenging status quos that don’t jibe with the facts.

I want to clarify something: I do so not question Conventional Wisdom because I fancy myself a contrarian for contrariness’ sake. I do it because there’s a lot of disinformation out there, horribly misguided or just blatantly false nutritional info that’s all the more dangerous simply because it has been deemed Conventional Wisdom by the omniscient “they” – who “they” are, it’s often difficult to know; just know that “they” know what they’re talking about (or so they say). If it were that crazy homeless guy outside the liquor store screaming about the dangers of a diet high in animal fats, it’d be easy to ignore. But when “they” happen to be a panel of experts in white coats hailing from important-sounding government acronyms, we tend to listen up.

CW rarely changes, but when it does, it’s generally for the better. I already mentioned the obvious example of smoking, but the Internet is making it harder and harder for unsubstantiated nutritional advice to go unchallenged. The bulk of people still get their dietary information from Oprah or the media’s cursory interpretation of the latest industry-funded study, but an increasing number of individuals are empowering themselves and others with the wealth of information available online. People no longer have to settle for a nutrition “expert’s” analysis of a particular study; they can access the same information and pull up the same abstracts and draw their own conclusions. And for those of us who might not have the tools or the time to break down each study, there are blogs like this one, or Dr. Eades’, or Conditioning Research, or Whole Health Source, or Richard Nikoley’s that do the leg work for you, making it incumbent on us to do our homework and make sure we don’t commit the same errors we criticize in the establishment. Of course, there is the fact that, though the Primal way is the right way, we cannot lose our skepticism. A new “alternative” Conventional Wisdom is emerging from the Primal/paleo/low-carb blogosphere, but it remains a vocal minority, and maintaining our intellectual rigor is crucial if we want to make an impact on society as a whole.

Like omega-3s, saturated animal fats, and brightly colored vegetables, a good-sized chunk of skepticism makes for healthy living. We have brains, big, immensely complex ones that are the products of millions of years of evolution, and we should use them. Grok didn’t rely on Conventional Wisdom; he created it. Accepting what “they” say on blind faith is tantamount to relinquishing what makes us essentially human: our ability to harness reason and logic in the pursuit of truth. At the same time, we must also probe, test, and constantly examine our own ideas.

And so, this guide does not purport to tackle every bit of misleading or false nutritional Conventional Wisdom (I think we do an adequate job of that in our regular daily posts); I simply wish to remind each and every one of you to never stop asking questions and seeking truths.

In the end, we subscribe to perhaps the most Conventional Wisdom of all – the time-tested, naturally-selected wisdom spanning hundreds of thousands of years, the wisdom, founded in the incontrovertible facts of evolutionary biology, that guided our ancestors. We may not ever change the minds of society at large, but we can make the small – or big – changes in our own lives that will ensure health, longevity, and wellness.

Prefer listening to reading? Get an audio recording of this blog post, and subscribe to the Primal Blueprint Podcast on iTunes for instant access to all past, present and future episodes here.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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44 thoughts on “The Definitive Guide to Conventional Wisdom”

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  1. The real problem is that modern conventional wisdom is no longer a simple and reliable collection of statements on how to live well, but has become a shifting, unstable dogma under the false pretense of scientific rigor. A similar thing happened to agriculture: now “conventional” agriculture means modern, chemical-intensive agriculture, while “organic” means, literally, conventional (i.e. pre-modern)…

    True conventional wisdom hasn’t changed, but its impostor is slowly taking its place.

  2. I suspect a lot of well-trained people unthinkingly accept what they read in their textbooks and espouse it as gospel.

    Then there is the class of strong-willed doctors and scientists (and these are the ones that seem to end up in charge of everything) who often have over-sized egos that won’t permit them to admit it when they are clearly wrong. Can’t lose face by reversing what they’ve preached for 30 years. Even if they could admit it to themselves, such admissions could be career ending and they know it.

    1. Slightly off topic but I think this comment nicely dovetails with religion too. I don’t think you will find a senior archbishop (whatever the higher ups are called) that believes their rubbish but they can’t break with tradition now and admit it and acknowledge that their entire life has been a sham.
      Back on topic, a lot of doctors can’t break with CW and admit that what they’ve been espousing for years is wrong. They have to keep pushing the CW line.

      1. Religion is conventional wisdom?
        They are quite the opposite, actually. Instead of being tempted to throw out what they have believed for centuries in favor of “modern” thought, they stick to their guns. If they were changing all the time (like conventional wisdom), then religion WOULD be a sham.
        Think before you open your mouth next time, sir.

        1. dude…”Confronting people in real life about deeply held nutritional beliefs (about as deep-seated as religion, in fact) usually doesn’t end well. Humans have a nasty habit of clinging on to dogma all the more vigorously when it’s threatened with logic and reason.”

          Aaaaaaannnnnnddddddd……you made his point.

      2. I agree about the religion comment. Religion changes according to politics. I highly doubt that the senior archbishop would ever go against what they’ve been saying for years, it would be a total embarrassment. Good point.

        (Religion IS a sham)

  3. I’ve run into a lot of the people who can’t imagine going against what has been drilled into their heads for years. When I tell them I’m not eating grains anymore, it is almost incomprehensible. I’ve also been told that I shouldn’t just “jump on the next trend” or “latch on to the first thing I read that I agree with.” I’ve noticed that once they have decided I’m outside the normal limits of CW, they try and defend what they know no matter what I say. Results will speak for themselves I believe, so in a few months when I am visibly healthier and they still feel down, maybe they’ll start listening.

    1. Trends? We have been eating grains for a tiny fraction of the existence of mankind. I’d say that eating grains is a trend; still in its infancy! 🙂

  4. When I was getting ready to make the change to a primal lifestyle I talked with my doctor about the primal lifestyle that I would rather hold off on taking the medication he was suggesting in order to try a more natural method. He threw up his arms and made a big fit then walked out of the room saying he was the doctor and if I knew better I could leave.

    I did leave and I’m doing better without his prescription. I agree that ego has much to contribute to the slow change of conventional wisdom.

  5. Awesome.

    I remember when I read the china study, I was sold.

    But then I found your website, and then I started questioning a lot of the authors studies, and how certain variables cant be controlled. He basically argued that a vegan diet is healthier than the “average” american diet. Assuming the average american diet is crap, then yes, he is right. But, i questioned his wisdom on how a vegan diet can be better than the PB diet… and I don’t think (or, know) so.

  6. I don’t think its generally in human nature to admit we are wrong – particuarly if something spends years upon years studying, learning, and trying to become an expert on something. But, I do believe that when one stops questioning (whether its conventional wisdom or one’s own character/personality) then we become stagnant and can easily stop improving ourselves and the world around us. Thanks for helping us keep questioning!

  7. Very true! Your post makes me think of how challenging it is to keep an open mind about everything. Many things come to mind:

    – The sense of peace people tend to get from embracing absolute certainty.
    – The practicality or necessity of trusting experts (not always) in fields outside our expertise.
    – The growing difficulty to discern from good and bad quality sources in times where we can get anything from the internet, and where only few have the skills to assess the methodological quality of a research paper.

    But, at the end, I think it comes down to embracing absolute certainty. The majority is brought up with the idea that absolute certainty is a virtue and that questioning is wrong. And the majority, voluntarily or involuntarily, remains doing it for good.

    1. You’re absolutely right, DaveC. I’m going to add it to the post now.

  8. Curious, does anyone know what countries were used in the Seven Country Study and which were excluded? Every site I’ve looked at seems to want to prattle on about how Keys manipulated the data but does not list the countries he used (aside from Japan, Finland, and Crete).

  9. Some people don’t want to take the time to truly learn about health, fitness, and eating. It’s far easier to spout back the bits and pieces that support what they want to believe, than critically examine their habits and adapt their behavior. If you don’t believe this, just listen to a smoker with lung disease protest how cigarettes aren’t dangerous.

  10. Only death changes the status quo as the stubborn egomaniacs that comprise “the establishment” who cling to their nonsense in the face of contradictory evidence finally kick the bucket so that honest curiosity finally enables fresh blood to rediscover what was already discovered years before.

    Wait long enough and the truth will out.

    But be prepared to wait an entire lifetime. That seems to be what is required these days.

  11. Wasn’t “seven countries” about total fat production in these countries and not just saturated fat?

  12. I know that Colpo listed which countries were used in the Seven Nations Study and which were excluded, along with the other possible scenarios in his book: The Great Cholesterol Con. I don’t have it here with me and the power supply on laptop is shot, where I’ve got the Ebook version. I will try and look up the info this weekend if no one else posts it.

  13. Great article Mark. Makes me more determined than ever to not blindly accept everything in life, across the board, not just in diet and exercise.

    I’m a cyclist, and cycling is chock full of false prophets espousing THE TRUTH on everything from helmets to pedals to nutrition. It takes a courage to be different in all facets of life. There are a few luminaries out there, Grant Petersen for instance, who dare to ask why? I’ve been following the PB now for 10 weeks since reading about it in the Rivendell Reader. I’ve lost 28lbs – I’m lighter now than when I’m in my teens, have no energy highs and lows any more and I’m eating real food. However, I get almost daily panicked remarks from friends and co-workers that I’m not cramming my stomach with ‘heart healthy wholegrains’ or eating a pile of pasta the night before a big ride.

    However, diet is no different to any other area of life, in that most people will always take the path of least resistence, expertly led by the nose by CW.

    Thanks again for a great post, and for helping me, at 36, to change my life.

  14. Mark, do you really believe that the “experts” that espouse erroneous doctrines on health (and other subjects) are good, well-meaning, altruistic people. I don’t. I consider these experts compromised, malevolent and self-serving. Ancel Keys and the 7 Country Study is a perfect example.

    The research that proposed that smoking was not harmful was funded by big tobacco and unwitting people repeated it as if it were gospel. The “experts” and celebrities that now ask us if we “Got Milk?” are funded by big dairy and could care less if it gives the right message because they got paid. Lies, half-truths and outright disinformation is what we are fed by these “experts”. I appreciate your encouraging your readership to think for themselves, but I also think that you are “preaching to the choir”.

    1. Some people who come here for the first time are just auditioning for the choir!! I was in a kettlebell forum, oblivious to the primal blueprint and in step with CW, when I followed a link to Mark’s “Chronic Cardio” post. Now I’m an established baritone but we all gotta start somewhere!!

  15. I do want to say this. It is without question that there is big money behind so-called expert advise. There is no question that there is influence and bias and *gasp* greed.

    However, not all experts, researchers, and scientist are a part of a cabal that feed the big money anything want to hear. Notice it is often the big money interest that twist the results to their liking outside the control of the “expert.” So much so to the ire of the “expert.”

    There are many well meaning researchers who perform vital work that has advanced our quality of life in so many ways.

    We as a consumer need to make judgment calls and weigh the facts on our own. It is that control our individual life and decisions.

  16. Mark,

    I enjoy reading your blog and I agree that conventional wisdom on nutrition seems to be lacking in both convention and wisdom these days. At least in the US we have given up on traditional ways. We don’t eat the way our great-grand parents ate much less the way grok ate.

    While I am down with you message, in my first step I am trying to achieve a life style that is maybe more like great-grandma’s than like grok’s

    It seems pretty clear to me that there have been at least 2 significant changes in CW that have been detrimental to human health. One happened 10K years ago when we started grow grains and the other seems to be 50 years ago when we decided that animal fat was bad. Grain didn’t kill us and make us all fat 10k years ago, that is a more recent occurrence. I say lets undo the more recent mistake first before we tackle the older one.

    On the other hand, I love the grok image, it is much more powerful than grandma with her cane and a better metaphor for healthy clean living.

    Keep up the good work and little by little the CW IS changing.

  17. Very interesting and thoughtful article. Thank you for the comments about smoking. We’re still finding out just how wrong that old CW was. For example, researchers just discovered that a key bacteria in gum disease alters its DNA and cell structure in response to cigarette smoke, making it more virulent and resistant to the body’s normal defenses. We write extensively about related issues at, especially the links between elevated blood sugar and gum disease that can interfere with diabetes control and significantly increase serious health risks such as heart attack, stroke and blindness.

    – Charles Martin, DDS
    Founder, Dentistry For Diabetics

  18. I’m smiling to myself as on MSN homepage there was a link to a blurb how coconut is good for you, eat grass-fed beef, the food pyramid might be wrong, etc etc etc… Is the CW startin to swang a little??

  19. In recent weeks there’s been a positive article on low carbing in the Daily Mail, one of the UK’s more reactionary papers, and also in Saga magazine – for the over fifties. Small steps in the most unlikely places.

    A friend has a useful line “absence of evidence does not mean evidence of absence”. This is one of the major habits of certain “researchers” and of course the likes of journalists.

    For example diabetics with A1cs in the fives are numerous in real life but not in research papers, in fact I know people who have been turned down for studies for being too well controlled. So the doctors believe such people do not exist and therefore cannot learn how they achieved this end or teach the techniques to others. They confuse the fact that it isn’t being studied with the fact that it isn’t being achieved.

    See also, other cardiovascular disease, obesity and all the other modern ills which mysteriously improve on a Primal lifestyle.

    Individually perhaps we can make our own doctors, nurses etc. question Conventional Wisdom by achieving the impossible and telling them how we did it. A few of them are now on board. But I wouldn’t let any of these guys treat my diabetes (or even an ingrowing toenail)

  20. I wonder if smoking is actually not as harmful if you’re on a paleo/low-carb diet, or even simply avoid Omega-6.

    I wonder if it’s possible there were no health issues 50 years ago. Maybe cigarettes started causing problems due to diet.

  21. “the incontrovertible facts of evolutionary biology”..
    Really? incontrovertible?
    Sounds like misguided CW to me!!!

  22. “the incontrovertible facts of evolutionary biology”..
    incontrovertible? Really?
    Sounds like misguided CW to me!!!

  23. I just checked the site for the Canadian Food Guide pyramid, and the recommended serving amount is 6 to 7 servings of grains daily!!!! No wonder everyone is obese!!!
    For meat it’s only 2 servings!!! CW is SO WRONG!!!

  24. The power of Conventional Wisdom is such that it can affect the awarding of research grants to scientists; some unpopular anti-CW proposals don’t get funded if the funding agency sees no sense in research efforts counter to the current and overwhelmingly-accepted viewpoints.

    I know this sounds paranoid, but the truth of the matter is that the grant awarders are only human, and see it as a waste of money and futile contrarianism to spend time and money on research into subject matter that they feel is already settled.

    How unfortunate in many cases; it means years may go by before a critical mass or tipping point from counter-evidence is reached, and the paradigm begins to shift.

  25. Do you think there is possibility that conventional wisdom may be false? Maybe it is the contrail of sloppy or self-interested thinking. For example, in 1980 Mitch Snyder said their were 3 million homeless people and that 45 died each second. Ultimately, when Snyder was pressed on his figure, he admitted it was a fabrication. Snyder was self-interested to the point of deceit. Do people create CW for their own selfish reasons?

  26. I think you should rebrand CW as Arbitrary Semblance of Science. The biggest problem is that CW dogma discourages people from exploring their intuitive common sense. We are still mostly living in the dark ages, only the “Inquisition” now have more subtle and persuasive ways of enforcing the commercially oriented ideology.

  27. I’m not even sure I believe the current CW on smoking. Yes, I agree that smoking as done by a typical smoker is unhealthy (my dad developed lung cancer after decades of smoking). I wouldn’t dream of becoming a typical cigarette smoker, but I’m not so convinced of the dangers of pipe smoking. I know that the typical cigarette was developed with toxic additives that increased addictiveness, leading to overuse and huge negative impacts to health. However I’m not convinced that there aren’t levels of smoking that are beneficial. I know that smoking tends to counter allergies, which I suffer from. I suspect that tobacco can be properly used somewhat medicinally in low dosages. You don’t take over-the-counter medications by the handful. Tobacco shouldn’t be consumed in that manner either. As with all CW, it’s difficult to find reliable data, and the data I’ve been able to find has not convinced me of the risks vs benefits.

  28. I don’t get it. Where is the guide to Conventional Wisdom? Is it linked from this page?