Is the Paleo Diet Supported by Scientific Research? – Part 2

Last week, I countered claims that “paleo gots no science” with summaries of five recent (and not so recent) papers supporting the paleo/Primal approach to diet. The reception to that post was strong enough that I got requests to cover a few more this week. So today, I’m going to explain the findings of five more relevant studies. Not all of these studies come from the original list, but each gives an accurate and important portrayal of the effects of eating in accordance with one’s biology. More importantly, these are all interesting approaches to the diet, with some examining higher-carb paleo, some looking at higher-fat and downright ketogenic paleo diets, and still others trying to disentangle the beneficial effects of the weight loss that normally occurs on paleo diets from the effect of going paleo.

Let’s dig right in:

Favourable effects of consuming a Palaeolithic-type diet on characteristics of the metabolic syndrome: a randomized controlled pilot-study.

This was a cool one because researchers were interested in the effect of paleo style eating on the metabolic syndrome absent weight loss. Everyone knows that weight loss on any diet improves symptoms of metabolic syndrome (hypertension, poor lipids, blood sugar disregulation, etc), so this study sought to uncover any effects unique to paleo eating. How’d it go?

First off, it was hard to keep paleo dieters from losing weight. Seven of the 17 subjects in the paleo group lost enough weight that researchers had to provide extra snacks to keep their weight up. Once they got that under control, good things happened:

  • Waist circumference decreased by 3.1 cm — an indicator of reduced belly fat, which is remarkable especially given the lack of significant weight loss (just 6 pounds on average).
  • Systolic and diastolic blood pressures dropped by 8.5 and 8, respectively.
  • Both fasting insulin and glucose decreased, indicating better blood sugar control and more fat burning.
  • Insulin resistance dropped.
  • Blood lipids improved, with total cholesterol, LDL, and triglycerides decreasing.

Takeaway: By all indications, metabolic syndrome patients can benefit from going paleo. If they were allowed to also focus on losing weight, I have no doubt that the numbers would improve even more.

Obesity and cardiovascular risk intervention through the ad libitum feeding of traditional Hawaiian diet.

At first glance, the abstract of the study suggests a diet at complete and utter odds with paleo. It’s low in fat (under 10% of calories) and protein, and high in “complex carbohydrates.” Complex carbohydrates, in modern parlance, are hearthealthywholegrains: breads, pastas, porridges. But in this study that attempted to recreate the pre-contact Hawaiian diet, complex carbohydrates meant roots and tubers like sweet potato, yam, breadfruit, and taro. In fact, grains were restricted because those were unavailable in the islands before Europeans arrived. The traditional Hawaiian diet used in the study, called the Wainae Diet, consisted of unlimited amounts of sweet potatoes, yams, breadfruits, taro roots, poi (a mashed and fermented taro), fruit, seaweed, and greens from sweet potato, yam, and taro plants. About 200 grams, or roughly half a pound, of chicken and/or fish were also included each day. All cooked foods were steamed, similar to traditional forms of Hawaiian cooking.

The macros are a bit different from what you’d expect from a paleo diet, but the food quality is in lockstep. No grains, legumes, dairy, seed oils, or processed junk food. No acellular carbohydrates (pulverized grains: bread, pasta, flour, etc). Lots of leafy greens and nothing but whole, unrefined foods.

What happened when a group of obese Hawaiians were placed on such a diet for 21 days?

  • Energy intake dropped by 41%. This is crucial, since food intake wasn’t restricted (except for the fish and chicken). Subjects were encouraged to eat to satiety, indicating this diet was pretty good at keeping them full.
  • They lost an average of 7.8 kg. They were still obese, but far less so than before.
  • Blood lipids improved. LDL and triglycerides dropped and even though HDL reduced slightly, the TC:HDL ratio improved.
  • Blood pressure improved. Systolic dropped by 7.8% and diastolic by 11.5%.
  • Blood glucose dropped dramatically.

Takeaway: Paleo diets can be high or low carb. Low carb does have a bit more clinical backing, and in my experience is more effective for the severely obese and easier to adhere to, but the important thing appears to be grain/junk food/seed oil avoidance. They had “sugar,” but it was in the form of fruit. They ate “complex carbs,” but in the form of starchy vegetables. Paleo is a framework and this paper illustrates that.

Three paleolithic ketogenic diet case studies.

And last, but not least are three case studies. Because these involve a total of three patients (being case studies), I’ve grouped them together. Alone, a case study does not an argument make. Three separate case studies showing massive benefits for the individuals involved, on the other hand, raise even the most skeptical eyebrow.

In the first, a 19 year old male newly diagnosed with type 1 diabetes (blood glucose levels of 384 mg/dL!) was placed on a ketogenic paleo diet after spending 20 unproductive days on the traditional low-fat, high-carb diabetic diet. This new diet consisted of meat (mostly red and fat-rich meat), eggs, organs, and fat, with insignificant amounts of non starchy vegetables for a fat:protein/carb ratio of 2:1. Plant-based oils and artificial sweeteners were restricted. The only supplement given was 5000 IU of vitamin D3.

Upon going paleo-keto, his blood sugar normalized, even postprandially (after meals). He was able to stop insulin treatment following his first meal. On the original diabetic diet with supplementary insulin, his average blood sugar was 119 mg/dL. On the paleo-keto diet without insulin, his average blood sugar was 85 mg/dL. Blood sugar fluctuations also reduced from a standard deviation of 47 mg/dL to 9 mg/dL.

After 6.5 months of the diet, he had maintained his progress without side effects. His LDL-C and total cholesterol had gone up, but that’s fairly standard on ketogenic diets.

In the second, a 65 year old obese female with high blood pressure, hyperglycemia, angiopathy (likely diabetic), and a history of gall bladder surgery and colonic polyps was placed on a ketogenic paleo diet. She was taking anti-diabetic and anti-hypertensive meds as well. On her new diet, typical foods included broth, stews, pork bone marrow, bacon, steaks, calf liver, and pork greaves (or cracklins/chicharrones). Vegetables like cabbage, onion, and root vegetables were used as garnish.

How’d it go?

Over the course of 22 months, she was able to discontinue eight medicines, her BMI dropped from 37.1 to 31.6 (lost 14 kilos and counting, at the time of the study’s conclusion), and a normalization of both blood pressure (along with no blood pressure spikes in the final six months) and blood sugar. That was purely from diet; no supplementation, no exercise.

In the third, a 7 year old with absence epilepsy was placed on a ketogenic paleo diet. Before the diet, she was socially withdrawn, hadn’t gained weight or height in two years, and wasn’t toilet trained; she was effectively developmentally disabled.

Based on meat, organs, fish, eggs, and animal fat, along with some vitamin D3 and fish oil, the new paleo-keto epilepsy diet had an approximate fat:protein ratio of 4:1, with very little (if any) carbohydrate. And it worked incredibly well. Seizures stopped six weeks in. She grew 3 kilograms and 6 cm in four months. Her mood and social function improved enough for her to attend regular school by study’s end.

Takeaway: A paleo keto diet using whole foods is just as, if not more effective, than a clinical ketogenic diet using refined, processed foods, whether the patient is a youngster with epilepsy, a young man with type 1 diabetes, or a middle-aged woman with metabolic syndrome.

However old (the Hawaiian diet study), limited in scope (the paleo-keto case studies), or small in scale (the metabolic syndrome study) these studies might be, they remain effective ambassadors for the efficacy and diversity of the ancestral approach to diet. So the next time someone says “Yeah, but what about those low-fat native islander groups?” or “But no studies exist showing you can safely eat bone marrow!” or “Ah, it’s just the weight loss helping,” you can direct them kindly to this post.

Again, let’s hear from you down below. What are your thoughts on the studies? Any surprises? Any disagreements?

Thanks for reading, everyone. Take care and good day.

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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58 thoughts on “Is the Paleo Diet Supported by Scientific Research? – Part 2”

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    1. What, no mention of coconut products? I thought Hawaiians had been inundated with them.

      1. Don’t quote me on this but I’m pretty sure Hawaii is the one place in the Pacific that coconuts never made it to (pre-contact that is!)

        It’s simply too far for a coconut to drift and have any chance of growing.

        1. Yes, they drift in the ocean. That’s how they proliferated across the Pacific region. Everywhere except Hawaii

      2. The coconuts may have been carried by African Swallows, as everybody knows

        1. African Swallows are non-migratory. So they couldn’t bring a coconut back, anyway.

        2. Wow I did not know MDA contains a full clan of the Monthy Python tribe
          Correction I googled it: I am not in the stage of knowing all the dialogs by heart, but “I am getting better”

          “It could grip it by the husk! “

  1. The Hawaiian diet study is going to cause a lot of controversy between high-carb and low-carbers. I agree on the satiety, and I agree that Paleo/Primal often places emphasis on the carbs while underestimating the effects of bad seed oils, especially on the blood numbers. However, in the Hawaiian study, the participants cut from 2600 to 1570 calories per day and lost weight from 304 pounds to 285 pounds. With numbers like that, wouldn’t almost any diet cause fat loss? Also, the subjects were native Hawaiians; would this diet have the same effect on people of European or African or other descent? This diet may work for the first 30 pounds, but what about Kelly Korg’s last 30 pounds? I wouldn’t call this a vindication of high-carb paleo (for weight loss) yet.

    1. I think the key point is the subjects were permitted to consume 3000 calories per day if they wanted to. However they were satiated at roughly half. This provides excellent support for the leptin hypothesis. Furthermore the study population of native islanders were isolated from grains longer than many cultures that still benefit from avoiding them. I would like to see how this study carried out for a longer period of time. The weight loss in 21 days was at a very health rate.

    2. I think of it as more of a good carb v. death carb battle. We eat death carbs here in the US, blood sugar spikes, then crashes (think of a 3 year old being given a ton of sugar). Most of us sit on our fat asses all day, meaning our glycogen stores are full. If we dump a ton of sugar in our blood at once, where does it go? The magical agri-fairy doesn’t remove it from your blood stream so you stay alive longer to eat more poison. What about the slow release carbs that slowly, and gently add a few twigs at a time instead of Optimus Carb pissing lighter fluid on it? It has to do with the thermic effect of food and so many other things that we probably can’t measure yet. (PS, I am in the lower carb camp).

  2. After 110 pound weight loss in a low carb/no carb diet, I am still down the weight. It’s been 12 years. All the low-fat crazies are free to tell me why I’m doing it wrong.

  3. The Hawaiian study is interesting because so many people are quick to slam paleo/primal eating for being low carb. It just shows that you can have more of a conventional carb ratio and see benefits as long as you stay away from the refined and processed stuff. For those that don’t need to lose weight or want to actually gain weight this approach may be something to emulate.

    1. I think Paleo/Primal gets slammed because most people have either limited or misconstrued knowledge of what it consists of. I’ve had people tell me they couldn’t handle a diet that consists of nothing but meat, which seems to be a common perception of a Paleo way of eating.

      There’s also misunderstanding as to what low carb really is. I read articles and comments all the time about someone going “no-carb”, when in fact they are referring only to grains and sweets and don’t realize that fruit and vegetables are also considered carbohydrates.

      1. +1

        Like most things, people like tear down and disprove things before doing the proper research or gaining a real understanding of what it is they are objecting to.

      2. Agreed, same thing happened to the Atkins diet: common misconception was that it was a high protein diet, when it fact it was high fat: find your level of carbs for the desired weight, and stay on it (with a proper gradation of stages). He was a hero.

      3. Ya… Agree with you Shary! Also, till today… there are still people saying that vegetables are fibers and no carbs in it!

    2. I don’t disagree that higher good carbs is okay “for those who don’t need to lose weight.” But how many people in the US don’t need to lose weight? My guess is the vast majority of America. The obesity statistics based on BMI are a crock. In order for me to join the ranks even of borderline “overweight,” (BMI 25), I would have to gain 25 pounds of pure flab over my ideal weight, and I’m 5 feet tall!

  4. I have actually left Paleo over the last year or so, but not for why people might think.

    1. I’m just a total animal lover. Call me names if you like, but it matters to me I’ve found and I have to live and eat with a way that agrees with my principles.

    2. Cost. #1 is always what it was about, but #2 has become a big issue here in Idaho the last couple years. I’m assuming the limited water and simply the cost of raising the animals is the main issue, but grass fed/organic meat here is a *lot* more expensive now than 7-8 years ago when I started down the Paleo wagon.

    Anyways – Just sharing what happened with me. Not trying to influence others, just sharing. Cheers all

    1. So, Buck….are you a veggie? What do you do for protein and how do you feel?….I love animals as much as you do and I also love that God left us some
      solid nutrition after the super nutritious veggies from the garden of Eden were gone.
      I believe one day we will be in that state again, but until then…I eat animals….
      (except my 3 pugs) just sharing

      1. is it because fish are mute that are considered ok on a vegetarian nutrition?dude?

        1. no, its because fish and seafood stuff have more micronutrient nutrition in them

        2. I don’t care about the veggie non-sense…I could almost be a veggie…
          but I don’t feel like it is the healthiest way to go….got to have some animals…don’t do fish then, just do high quality eggs…I know they are mute…

        3. Fish don’t have eyebrows and thus can’t make facial expressions. So eat up!

    2. Ok, i am an animal lover too. 1 grass fed cow grazing on some hill = one death plus a few unlucky frogs the cow happens to step on.

      One kilo of veg stuff = thousands of animals killed/displaced to make way for grains/mono crops not to mention destroyed topsoil. You can’t grow grains or soy on hills. you can feed grazing animals just fine.

      Why is a cow’s life more important than a rabbit or other wild animals that are destroyed by farming?

      So your number one reason makes no sense really.

      #2 is totally valid point.

  5. Not surprising at all that real food trumps processed. Hopefully more and more studies come out to show this and we can stop hearing the “no science” once and for all. Definitely a long way to go, but I’m hopeful.

  6. Here’s a better question: what if it didn’t matter what science says about anything primal. The essence of primal is that the only justification required is that it was a part of a human’s primal existence. End of story. That is my approach to primal, since a primal existence is by definition the longest and most extensive case study ever conducted. No debate is more valuable than that. What a great world it would be if we all just did what worked rather than let science lead us around by the nose; often with destructive results.

    1. HEAR HEAR!!!!!!

      Finally some sanity in the above comment from Dave. The human species has shifted from listening to everything the marketing crowd tell us (without evidence) to everything the science crowd tell us (which is then used by the marketing crowd).

      We got along fine without science and marketing for several million years… Follow your heart, your gut and apply some common sense people.

      Born to run???? Nope… Born to move constantly, lift heavy things and sprint like hell once in a while.

  7. Oddly enough, when I started my primal journey, I started feeling compassion for all food sources, not just animals. I am vehemently against factory farming, and would easily be a vegetarian or a vegan if that were my only choice for a meat source. But for some reason, I started seeing plants as having the same dignity to life as animals. We are all in this together, plants and animals. Plants have to die to give me nutrients just as much as animals. I feel a tremendous amount of gratitude for the foods that I purchase and eat. I thank both plants and animals for allowing me to use the nutrients they’ve stored in their bodies, and I feel together we become one living being instead of several. That is also a very strong motivation for me to stay healthy, so their sacrifice will not wasted on someone who doesn’t care about the body they are helping to keep alive.

    1. I have similar feelings, not so much thinking that plants themselves sacrificed a fulfilling life to feed my body but I certainly consider the wildlife that lived in the environment in which my food was grown, or the third world farmer that had to grow and harvest the food.

      I’m not sure how true it is but someone told me almost all banana farmers are infertile thanks to the chemicals they must use.

      When it comes to animal produce the feeling is even stronger.

  8. I guess the high-carb Hawaiian paleo diet helps me understand these 30 bananas a day idiots that love to poke fun at the paleo diet (whilst looking like naive morons!)

    Maybe they’re feeling as good as us primal lot, in truth Mark’s 3 rules (no grains, no vegetable oil & no sugar) hold perfectly true for many diets.

    Of course I personally eat fat like it’s gone out of fashion…. wait a minute!

  9. I actually never mentioned that plants gave up a fulfilling life to feed my body, just that in the grand scheme of things I don’t feel I have the right to decide where to draw the line on what has living dignity. That is my entire point, so I see everything that I decide to eat as having significant value in its own right,

  10. I don’t understand why all these big companies, diabetic associations, dietician’s et al, are still refusing to accept that the paleo/primal way of eating fresh fruit, veggies, eggs, meat and fish and removing all the processed crap & junk, is good for us humans.
    There are millions of us doing the primal/paleo thing and taking back our health and wellbeing. I’ve had people rear back in horror when I tell them I eat bacon & eggs for breakfast – all that fat and I eat butter and follow a paleo way of eating. They think I’m crazy and one person told me that my way of eating is dangerous as I’m not eating grains.
    Yeah, right!
    They’re still 40+ pounds overweight and on prescription medication for things like acid reflux and joint pain. My weight is normal and I don’t take medication for anything.
    One friend of mine has gone paleo after liking how well it has worked for me and he is stoked to have lost over 20lbs in the last 4 months and his overall health has improved out of sight since ditching the junk food, cutting way back on sugar and anything made with grains.

    1. Four foods which are the most fattening: Corn, wheat, rice, soy.
      Four foods which are the most subsidized: Corn, wheat, rice, soy.

      That should solve your confusion.

      1. I totally get that. So naturally in my country Australia, and probably the USA, it is so much cheaper to buy corn/wheat/rice/soy products. If you unfortunately need a charity food hamper, it’ll be full with bread, rice, unbelievably processed foods, sugars and the odd canned fruit or vegetable. Its disgraceful that a basket of quality meat, fruit and vegetables cost so much ore than a basket of bread, snacks, frozen pizzas and pastries and soft drinks.

    2. I had a similar debate with friend of mine when he found out I was primal. He disagreed that with me that we haven’t changed genetically from our H/G ancestors and said that 10,000 years was more than enough time for us to genetically evolve.

      I responded with this question; “if that’s the case why are you fat”?

      Cue embarrassed blushing face and lots of spluttering. Don’t worry I apologised and he’s still fat.

  11. Paleo/Primal and WAP diets are backed both by science and evidence, and I am not just referring to the recent case studies of people losing 120 pounds and improving blood lipids: traditional diets worked for centuries or millennia.
    The USDA dietary recommendations did a disaster in just a few decades.

  12. The Sci Babe believes their is no scientific proof of the Paleo diet being more benifical, and she claims she is all about science.

  13. Whenever I see a really overweight person struggling around with a walker or looking uncomfortable in their skin I have to resist the urge to sidle up to them and tell them how much better they would feel if they gave up bread and grains for starters.

    As a former visiting nurse, I recognise those who live on the very cheap and easy versions of a diet. Bread, margarine and some cheap spread with loads of cups of tea, and with cakes and pastries to fill up. There is not a good concept of nutrition to be found in many quarters of society, particularly among the poor or marginalised.

    Often this way of life is due to a mistaken view of financial management as good protein can be costly, and successful marketing can be persuasive.

    Soon I hope the Paleo message will reach the mainstream proper and we will reverse much of the ill health in society. Hospitals might not need to be so huge!

    I am thankful that I understand the message now and look back aghast at the nutritional mistakes that I have made over the years.

    Thanks to all of those who helped me to go Paleo.

    1. When I used to visit my grandmother as a kid, she’s serve us bacon and eggs for breakfast, and meat and roast veg for dinner – eating a similar diet herself.

      When our grandfather passed away and she moved to a nursing home, within a year she ballooned from 55kg to over 100kg and developed diabetes. Given residents are served cereal for breakfast, a sandwish for lunch, tea/coffee with milk 4-5 times a day and mashed potatoes for dinner, I’m not surprised.

      It’s heartbreaking to watch loved ones deteriorate in a place where they’re meant to be cared for by following modern dietary guidelines.

      1. I’m about to turn 66, so this issue is increasingly on my mind. Seriously, I think I’m going to starve to death, unless the medicos get a clue…

  14. Thanks for reviewing the literature and providing good synopses for 10 articles for everyone to look over, I really appreciate your all your hard work for not only these articles but keeping this site up and running! I haven’t had time to perform a good lit search, but I would be curious to see the articles that do not support a paleo diet, what their methods were, and why they concluded what they did. In the scientific community it’s great to find and read the articles that support your opinion/viewpoints but it’s sheds a whole new light on things when you read those journal articles that do not support your current thinking.

    Mark, have you come across articles thar are “anti-paleo?” Would you be willing to review some of those as well? Also, are there any systematic reviews on the topic (you may have already reviewed them on your site)? Thanks again for all your hard work!


  15. Science, reports etc…personally look where these have got us in the past. I was one that fell victim to the good old 80’s Low Fat Diet and thought I was doing my family a favour!!! I take these so called studies (usually paid studies) with a grain of salt. Their results are usually geared at the unhealthy money making industries. There is no money to be made from someone that doesn’t buy most of the ‘food’ in supermarkets and never needs to go to the docs.
    Eating a whole food diet as close to nature as possible without processing is simple and easy and I have all the proof I need in how my own health is.
    i don’t think we will ever see a major study done and I doubt paleo will ever be promoted like the Food Pyramid was….. Money it’s all about money and we have to make our own informed and educated choices.