Debunking the paleo diet

Paleo diets are the flavour of the month. Their premise is that our hunter-gatherer genes are out of kilter with our modern agriculture-driven diet and this disconnect is making us all sick. Adopting the diet of our ancestors is considered to be the pathway to health. Sounds plausible enough, yet critics say it’s based on false assumptions.

What are paleo diets?

Although paleo diets come in several guises they are all based on a similar theme. Throughout most of our time on planet Earth humans were hunter-gatherers eating game meats and wild plant foods and this shaped our genetic make-up. The development of agriculture during the last 10,000 years radically changed the human diet yet, as human evolution is slow, we have essentially retained our ancient genes. The mismatch between new diet and old genes is the root cause of high rates of obesity and other chronic diseases in the modern era.

The proposed solution is to eat like a caveman. Modern day paleo diets rely on meat, fish and seafood as staple foods. Fresh fruits and vegetables, nuts and seeds, eggs and healthful oils are all recommended. Sugar and many processed foods are restricted, though paleo diets also restrict grains, legumes, potatoes and dairy foods, which are fixtures in many healthy eating guides. The argument goes that these foods were all recently introduced into the human diet and are deleterious to health.

That’s the theory but critics of paleo diets are now coming out in force.

Critic No. 1: the evolutionary biologist

Professor Marlene Zuk, an evolutionary biologist from the University of Minnesota, argues that modern paleo diets are based on pseudoscience and speculation rather than actual research. In her book titled ‘Paleofantasy’ she argues that the paleo diet concept is based on misconceptions about how evolution works. She challenges the notion that human beings were ever perfectly adapted to their environment. The idea of past harmony and current discordance is little more than nostalgia, a yearning for the good old days.

Image: source

Professor Zuk dismisses the idea that modern humans have basically stopped evolving. Rather than modern humans being stuck with Stone Age genes she argues that we evolve more quickly than might be expected. Zuk highlights the increasing prevalence of lactase persistence as an example.

All mammals suckle their young and the newborns all have the enzyme lactase to break down lactose, the sugar in milk. The enzyme is lost after weaning in all species of mammals, except some humans. Persistence of lactase emerged in humans in Africa and Europe at about the same time as humans began to herd cattle, about 7000 years ago. Presumably the ability to easily digest milk conferred a survival advantage as lactase persistence has been spreading ever since. Now, 35% of the world’s population can tolerate milk products. A food that was unsuitable for Stone Age humans is now acceptable to billions – evolution at work.

If you have a spare 60 minutes take in Marlene Zuk’s lecture on the topic.

Critic no.2: the archaeological scientist

Dr Christina Warriner from the University of Oklahoma takes aim at present day paleo diets saying they have ‘no basis in archaeological reality’. She should know as she is an archaeological scientist who studies the health and dietary histories of ancient peoples using bone chemistry and ancient DNA.

Warriner dismisses the very idea that there was one diet that adequately describes the way ancient peoples ate. Firstly, primitive diets varied greatly according to latitude. There is no doubt that people living close to the Arctic ate a diet based on meat, fish and seafood – there was little plant food available. But plant foods were abundant in the tropics and undoubtedly formed a larger part of the diets of humans living in these areas.

Primitive diets also varied greatly with the seasons. Plants produce seeds and fruits at different times of the year, and animals migrate and fish spawn on a seasonal cycle. This ensured that primitive diets varied from month to month. It also demanded that people move from area to area to make the most of available food resources.

What about the idea that Palaeolithic peoples did not eat grains and legumes? It’s another myth, according to Warriner. She cites evidence that 30,000 years ago primitive humans were using stone tools similar to a mortar and pestle to grind seeds and grains. More tellingly, studies of fossilised human dental plaque have found remains of grains, legumes and tubers – all on the banned list of modern paleo diets.

Image: source

Warriner also makes the point that the foods recommended in modern paleo diets bear little resemblance to the foods our ancestors ate. In fact, virtually all of the recommended foods are products of modern agriculture. Modern day carrots, fat and sweet, are nothing like the small, fibrous, bitter wild carrots from which they were bred. Broccoli is ‘a human invention’. Bananas are the ultimate product of modern agriculture, totally dependent on humans for their reproduction. To Palaeolithic peoples meat typically meant lean meat from small game animals, together with the organs and bone marrow – quite different to the meats consumed in quantity by 21st Century cavemen.

Christina Warriner’s presentation on this topic is a must (22 minutes).

Reality check

So the assumptions underpinning paleo diets are highly questionable, but do they have a place nevertheless? Paleo diets may well be a useful approach to weight management – follow any restrictive diet and body weight will fall. Men, in particular, may respond better to a paleo diet than other approaches to weight reduction.

However, paleo diets are hardly a prescription for modern public health nutrition. For a start, paleo diets are expensive and out of reach of those most in need of healthier diets. As well as being sources of essential nutrients and fibre, grains, legumes and potatoes are all relatively cheap. And why would you recommend that people avoid nutrient-rich dairy foods, especially as calcium is a limiting nutrient in some diets?

As the world’s population increases towards a peak of 9 billion people there is no way that they could all be fed according to paleo principles. Like it or not, modern agriculture will be the only way to feed all those hungry mouths.


34 thoughts on “Debunking the paleo diet

  1. Christina Warriner’s presentation is excellent, and the archaeogeneticist perspective is great. She basically advocates for herbal medicine – a much sounder strategy than many modern interpretations of the “paleolithic” human.

  2. Amen!! This is a fantastic article. I love the experts referenced and all the evidence outlined.

    That’s very interesting about finding grains in the teeth of ‘cavemen’. I’ve always wondered about why grains and dairy foods are forbidden on the paleo diet… It’s very sobering to read exactly why that’s a load of mhmmm.

    Great read, I’ll definitely be sharing it!

  3. I wholeheartedly agree with the logic fault of “we should eat certain things because cavemen did” (especially when they didn’t!) however it’s worth pointing out a few things;
    - A ‘paleo’ diet restrictive by volume (caloric or otherwise). It a qualitative description, not a quantative one.
    - Grains, legumes, etc simply don’t stack up as sources of nutrients compared to leafy vegetables or lean meat. Furthermore their stimulation of an inflammatory response is well documented.
    - To the point regarding cost, the last time I did the shopping, broccoli and chicken breast were far from breaking the bank.
    - While I don’t agree with the logic of the ‘paleo’ diet, it provides a rather effective alternative to the Australian Guide to Healthy Eating (24 slices of bread a day anyone?) which is simply regurgitating redundant or disproven ideas from 50 years ago, which has arguably lead to the current state of poor health in Australia.

    A paleo fence sitter.

    • Hi Jake
      You will never hear me defending the old Australian Guide to Healthy Eating with its prescription to eat vast amounts of carbohydrate and negligible fat (even unsaturated fats). One of Australia’s leading dietitian-nutritionists told me that she once gave a community talk on the AGHE. When it got to the recommended amount of bread she said of her audience “I lost them and never got them back”. The message was just totally unacceptable to the general public, which would have been detected during the development of the AGHE if rudimentary consumer testing had been undertaken. And that was Australia’s national food guide for 15 years.
      The point of my blog was that the assumptions underpinning paleo diets are questionable. We need to base dietary advice on sound assumptions, based on science. Regards, Bill

      • Bill the Harvard School of Public Health conducted a 2 year study comparing a Low carb, mediterranean and low fat diets. The Low carb (see Paleo) out performed the other two in weight loss and insulin sensitivity and all other markers tested. having personally tried all 3 diets my own experience confers with this research. So while the meditteranean diet is good, Paleo is better!!

        • KayJay, I don’t support high carbohydrate diets. Please read everything I have written on the topic in the last five years. Regards, Bill

    • Seasonal fruit and vegetables are extremely cheap. There are also plenty of very cheap sources of low fat meat and fish (eg lambs hearts, hearts, kangaroo mince and canned mackerel).

      The best source of dietary calcium by far is green vegetables -not dairy. [ In fact milk would never be allowed on the market if it was required to the safety test required of food additives].

      Unfortunately national dietary recommendations are not really based on science They are the mostly the result of lobbying . The Dietitian’s Association of Australia sold it’s soul to the food processing industry many years ago. The DAA dietary recommendations are invariably based primarily on products produced by the major DAA sponsors. A few years ago the DAA was even recommending confectionery as part of ‘balanced’ diet [coincidentally Nestle was major sponsor at the time].

      • Some bold claims here Andrew!
        In relation to dietary guidelines being ‘mostly the result of lobbying’, I partly agree. But it’s not just industry lobbying. There is also lobbying from all sorts of non-industry groups, mainly arguing philosophical points of view. I have seen industry groups argue strongly for the science against ideology, so who the good guys and the bad guys are depends on your point of view.
        A colleague recently said that ‘policy is politics’ and that’s what we got with the dietary guidelines. The NHMRC should have done a better job in ensuring that nutrition science held sway (in my opinion).
        Regards, Bill

      • Don’t you have to eat a truckload of green vegetables to meet your daily calcium requirements? So basically it can’t be a sole source of Calcium?

        I think you hit the nail on the head Bill. People see results when switching to a Paleo diet primarily because they are eating healthier than before they started. But first and foremost they should be focussing on getting their daily dose of all nutrients – something vegetarians, vegans and paleo peeps need to be conscious of.

        Duncan Owen

        Healthy Weeknight Dinners

  4. Hi Bill, really like your approach to these topics. It helps immensely to provide another well backed up point of view when clients ask regarding these new diet fads that come up. Keep up the good work!

  5. Two of Warriner’s points are well understood and expounded upon in pro-Paleo literature:

    “Firstly, primitive diets varied greatly according to latitude. There is no doubt that people living close to the Arctic ate a diet based on meat, fish and seafood – there was little plant food available. But plant foods were abundant in the tropics and undoubtedly formed a larger part of the diets of humans living in these areas.

    Primitive diets also varied greatly with the seasons. Plants produce seeds and fruits at different times of the year, and animals migrate and fish spawn on a seasonal cycle. This ensured that primitive diets varied from month to month. It also demanded that people move from area to area to make the most of available food resources.”

    There isn’t anything controversial about this. Paleo nutritionists advise people to go with the seasons as well, eating what is locally available, getting variety throughout the seasons. Undoubtedly people over time have had lean years and plentiful years, and great changes in the kinds of foods available. Those who wish to engage this kind of eating should mix it up! Get variety, day to day, month to month.

    Zuk’s comment on evolution is understood as well. Pro-Paleo literature done well understands evolution and the body’s ability to adapt, and preaches self understanding and observation. Take an inventory of how you look, feel and perform. Get youself a full blood panel and understand everything from lipids to trace minerals. Capture these as a snapshot, a point in time. Then excise grains, legumes, dairy, processed foods and sugars, etc, everything artificial from your diet for 3 months. Eat as much natural food as you desire. Seriously, eat as much salad and natural animal products as you desire. It will be less than you think or are used to. Understand your cravings and your moods, your nutrition. Eat a great variety of animals and vegetables. If you don’t look, feel and perform better, and if your blood panel has not trended upward in all areas, then feel free to go back to your previous ways (but be sure to give it at least 3 months). Artificial and processed products will still be on the shelves waiting for you, they aren’t going anywhere. If you’ve seen all the improvement, consider making this diet a permanent lifestyle change.

    I also find it interesting that under the “Reality Check” section of this post, the objections to Paleo are economical, not nutritional or health oriented. Certainly the Paleo diet is not the cheapest. It costs much to eat clean and healthy. A few considerations come to mind here, though. First is that you will purchase and consume less, because you’ll be more satiated and nourished by the quality of what you eat. The health benefits of this approach are enormous and should be obvious. Secondly, the cost of health issues later in life should be weighed against the cost of healthy food in the present. McDonalds is cheaper today, but colo-rectal cancer and heart procedures are pricey in the future, for instance.

    Paleo doesn’t claim to be the cheapest (although in the end I think it is, or at least a wash).

    • David – maybe then there are two Paleo diets. One is as you describe which is basically a low carb diet, and the other, understood by 99% of people who read about paleo diets, and what that means, is the one that bans dairy, grains and legumes.
      Surprisingly I don’t hear anything from the “real paleo” experts pointing out they have been misrepresented, except, as on this blog when the paleo diet is shown to have no basis in genetics, one of it’s core claims.
      Also “seasonal” eating now is quite different from seasonal eating 10,000 years ago. New strains of fruit and vegetables mean the growing/harvesting season is longer and more robust to the vagaries of weather. Perhaps a true paleo dieter would, if consistent, almost starve themselves to death every 10 years, reduced to a diet of grass and bark. (that’s a joke)

    • There are many non-dairy sources of calcium. The message thanks to AGHE and others (Dairy Australia for example) is that dairy has calcium therefore if you are not having three serves a day you are risking osteoporosis. I work in Public Health and I agree that dairy is the cheapest and most efficient way to get calcium but this is really only because it is the status-quo. If figs and green vegetables were seen to be as ‘common’ as milk, Coles might start a marketing campaign to make them very cheap too (‘because everyone eats *insertproducthere*). When you work in nutrition it is easy to hate the paleo diet because it challenges what we take for granted but it is always a good thing to have our presumptions challenged, albeit in a safe environment. I’ve been vegan and still lean that way and calcium is not a problem, even Foodworks says so! Having said that, paleo/vegan/fruitarian eaters make me anxious because they get really bloody aggressive sometimes!! But then so are dietitians and you only have to look at the whole ‘toxic sugar’ thing to see our nasty side. I’m open, I respect whatever, we have to if we are going to reconcile differences in the public health realm.

  6. Hi, Bill! I hope you can give some enlightenment on whether dairy especially cow’s milk is necessary in one’s diet. I’ve researched on it and read a lot of contradicting ideas. Thank you!

    • Hi Maria. I don’t think any food is ESSENTIAL in the diet. If you go back 10,000 years human diets were incredibly varied and there was little milk consumed. But we survived. Given that we have a big dairy industry now everyone in this country has the opportunity to include or exclude milk in their diet. It’s certainly nutrient-rich and the aqueous part appears to be protective against high blood pressure. The fatty fraction – not so good. So reduced-fat milk is fine by me. Regards, Bill

        • When you ask how old the average caveman was, you did not really ask a question that imports on diet and the health thereof. Life expectancy is very different from longevity.
          Cavemen -if we take ‘modern’ hunter gatherers as a model- mainly died of child mortality, warfare and violence (averaging about 30% of all males), infections and famine (food insecurity). A hunter gatherer reaching the age of 45 has a life expectancy of well over 20 more years.
          The very recent increase in life expectancy at birth is mainly due to better sanitation, clean water, vaccination, food security, electricity and a more or less effective judicial & policing system (modern state). The increase in wealth brought by the industrial revolution allowed for all this.
          The ‘diseases of civilisation’ only impact in later life and hence have only a relatively small impact on life expectancy at birth.

          • I would appreciate if someone could pass on peer reviewed scientific literature that supports what your saying. I would also like the peer reviewed scientific literature that supports ‘paleo diets’.

        • Kate you don’t really want to read peer reveiwed papers. You just want to criticise! Harvard School of Public Health did a 2 year study and the low carb (Paleo) out performed the Meditteranean and low fat diets! How is that for you?

  7. Hi,
    Nice article. I’d agree with most of it.
    I’m not a paleo fan really, but I don’t think its a bad diet, just a little heavy on meat and I really don’t get the exclusion of legumes. I don’t know where the idea legumes are not natural or are low in nutrients. For my part, severly reducing meat was what brought my lipids under control.
    On dairy I do agree with the paleos. I’m surprised its still recommended so much considering the decent body of evidence against consuming dairy. I for one would much rather get my calcium from greens ( or plant milks) than ingest the questionable proteins and hormones present in milk.


      This article might provide with reasons why we don’t recommend getting calcium from only vegetable sources. I have no idea why paleo and other dieting people seem to think dairy foods are terrible for us. I know some misguided vegans have told me because baby cows drink milk and become adult cows, all dairy products must therefore be bad. So I am not really sure where everyone is getting all this information from.
      Milk is one of the best available sources of calcium and is a great source of protein. Its also a nutritious satiating snack.

  8. I’m quite astonished that Zuk still gets cited given that i) she fundamentally misunderstands the paleo position, ii) her ‘dairy’ argument is transparently specious.
    All paleo advocates argue that humans ate a wide variety of diets throughout the evolutionary history. The ‘paleo diet’ doesn’t call for a fixed proportion of macronutrients or foods.
    Dairy- if you think about it for 2 seconds- is a superlatively inadequate example of quick evolution. Dairy isn’t an evolutionarily novel foodstuff: it’s, in fact, the ONLY foodstuff that all humans everywhere have eaten, and indeed, the first food that they’ve eaten. That a minority of the world’s population has evolved the tendency to maintain their lactose tolerance if anything shows the importance of our evolutionary history and the slowness of our capacity to evolve.

    On the grass seeds evidence: the archaeological evidence here is being blown way out of proportion in order to comport with our modern confirmation bias. Yes traces of grass seeds have been found in cooking vessels and teeth, but there’s been no argument or evidence for the idea that we could gain significant calories from gathering wild grass seeds (give it a try).

    On the fact that carrots and broccoli are evolutionarily novel foodstuffs: yes, but paleo doesn’t advocate the importance of foodstuffs per se, but rather what the biochemical makeup of the foodstuffs is. So the fact that carrots in their current form didn’t exist is irrelevant if comparable fibre+sugar+micronutrients did exist.

    “To Palaeolithic peoples meat typically meant lean meat from small game animals, together with the organs and bone marrow – quite different to the meats consumed in quantity by 21st Century cavemen.”
    Has the author read any paleo blogs or spoken to any paleo people ever? The paleo community is fanatically obsessed with grassfed, bone marrow, offal and bone broth to ensure amino acid balance.

  9. Marlene Zuks book is excellent on evolutionary biology, but very weak on the ‘paleo diet’. Her sources about Paleo-diet appear not to be the scientific literature , but blogs and web-sites, great sources of reliable information, as we all know.
    Christina Warriner opposes an imaginary red-meat, macho type of diet she contends is the paleo-diet, and subsequently advocates a diet that actually is broadly a pale-diet. The consumption of grains before the advent of agriculture hardly mean they were staple foods.
    As far as the reality check goes, indeed, starches (and we mean the energy-dense acellular carbohydrates there) are implicated in many diseases: obesity, hypertension, atherosclerosis (and hence heart attack and stroke), diabetes type II, gastro-oesophagal reflux disease, ankylosing spondylitis with acute anterior uveitis (AS & AAU), multiple sclerosis and other neuro-degenerative diseases, and quite a bit more. What you spend on better food will be paid back in lower medical bills ten times over.
    It is true that with present technology we cannot feed 9 billion without starches, but that does in no way impact on the health benefits of the paleo-diet itself, which is mainly based on cutting starches.

  10. I like what Dr Louise Humphrey, a paleo dietary researcher at the Natural History Museum in London has to say about this: “There is no such thing as a paleo diet, paleo humans ate whatever they could find”.

  11. Please list one nutrient other than glucose that is found in unfortified grains that can not be found in greater abundance in either veg, fruits, nuts, fish or meat?

      • Here are a few clinical studies on paleo diets, I suggest people read them and come to their own conclusions:
        “Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study”
        “A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease”
        “Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes”
        “A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs”
        Jönsson et al
        O’Dea K. “Marked improvement in carbohydrate and lipid metabolism in diabetic Australian aborigines after temporary reversion to traditional lifestyle”. Diabetes. 1984;33(6):596–603.
        Frassetto LA, Schloetter M, Mietus-Synder M, Morris RC, Jr., Sebastian A. Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. Eur J Clin Nutr. 2009;63(8):947–955.
        Osterdahl M, Kocturk T, Koochek A, Wändell PE. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. Eur J Clin Nutr. 2008;62(5):682–685
        Neuromuscular electrical stimulation and dietary interventions to reduce oxidative stress in a secondary progressive multiple sclerosis patient leads to marked gains in function: a case report
        David Reese, Ezzatolah T Shivapour, Terry L Wahls, Shauna D Dudley-Javoroski, Richard Shields
        Cases J. 2009; 2: 7601. Published online 2009 August 10. doi: 10.4076/1757-1626-2-7601
        Agrarian diet and diseases of affluence – Do evolutionary novel dietary lectins cause leptin resistance?
        Tommy Jönsson, Stefan Olsson, Bo Ahrén, Thorkild C Bøg-Hansen, Anita Dole, Staffan Lindeberg
        BMC Endocr Disord. 2005; 5: 10. Published online 2005 December 10. doi: 10.1186/1472-6823-5-10

        • Hello Julianne. I’m glad you mentioned the seminal study by Kerin O’Dea in 1984. But you need to be careful about what you attribute to a Paleo diet.
          Those indigenous Australians who adopted the hunter-gather lifestyle effectively went on a 1200 calories diet, with high physical activity, for seven weeks. All lost appreciable weight, averaging 8kg. No wonder their blood glucose and blood lipids improved – they would have improved irrespective of the composition of the diet.
          Interestingly, their diet wasn’t low carb; it was low fat. Regards, Bill

          • I’m not someone who thinks that paleo has to be low carb. Nor do I think it should be high fat or high saturated fat. I look at a macronutrient ratio that is supported by science for my clients.
            The O’Dea study shows us what happens when people embrace a hunter gatherer lifestyle – it gives us much to learn from.
            Many of us who embrace paleo as a diet embrace lifestyle too.
            Eating less, moving more, circadian rhythms, sleep are all important.

      • Bill, you seem to be implying that Jullianne and other experienced nutritionists should not be listening to their clients and passing on what they learn from them, but instead pass on to those clients the debunking notions of Zuk and Warriner, who are not nutritionists and have no clinical experience or responsibilities.
        I doubt the concept of “anecdotal” or (“unpublished”) has the same distinction today, when anyone can copy official medical records and laboratory results directly into an blog post. It used to apply to the things one heard third hand about the auntie of a friend of a friend.
        Do you understand the difference between an anecdote and a case study?
        Type 1 diabetes mellitus successfully managed with the
        paleolithic ketogenic diet [external link]

  12. The Paleo Diet’s ENTIRE PREMISE is totally wrong. Cordain, Sisson, Wolfe …..NONE of those hucksters understands evolution. Richard Dawkins would laugh at them.

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