And like CrossFit and IF, the Paleo Diet also has some big promises to make good on if you’re to listen to the hype.
According to its more fervent supporters, the Paleo Diet is the ultimate way to eat. The commonly touted benefits are quite impressive:
- Rapid, easy weight loss without having to “count calories.”
- High, balanced energy levels with no crashes.
- No cravings for junk.
- Better workouts.
- Protection against various types of disease like cardiovascular disease and diabetes.
- Clearer skin and prettier hair and teeth.
- Reduced allergies.
- Improved sleep.
In short, many gurus sell the Paleo Diet as the ultimate “diet hack.” A way to put the power of genetics on your side and positively alter how your genes express themselves.
And if you combine it with CrossFit? Well, have you ever wanted to be superhuman?
Jokes aside, can the Paleo Diet actually deliver on these claims?
Let’s find out.
Paleo is a contraction of paleolithic, which refers to the Paleolithic era in history, which was a period from about 2.5 million to 10,000 years ago. During this time period, humans grouped together into small, roaming societies and developed simple tools to hunt and fish with.
The idea behind the Paleo Diet is to “eat how our ancient ancestors did”–a diet mainly consisting of fish, grass-fed meats, eggs, vegetables, fruit, fungi, roots, and nuts. That’s why it’s also called the caveman diet, the stone age diet, and the hunter-gatherer diet.
The foods excluded from the Paleo Diet are grains, legumes (peanuts, various types of beans, and chickpeas) , dairy products, potatoes, refined salt, refined sugar, and processed oils (trans fats, as well as refined vegetable oils like canola, safflower, and sunflower oil).
As you can see, it’s an inherently high-protein, low-carbohydrate, high-fat type of diet, and has you eating a ton of animals and animal products.
If that sets off alarm bells in your head, warning of impending heart attacks or worse, hold your horses. We’re going to address the health aspects of the Paleo Diet in a minute, but first, let’s start with a quick review of its theoretical foundations.
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That’s the first question I wondered when I heard about the Paleo Diet.
Who cares how our ancient ancestors ate?
Well, the Paleo enthusiast would reply, for millions of years (before the Age of the Big Mac), us humans were hunter-gatherers. We had no agriculture, grocery stores, or ways to store and process food. We had to eat nuts, wild plants, and fresh meats. And, he will proclaim, we were much healthier back then–no arthritis, no cancer, no osteoporosis, and no heart disease. Thus, he will conclude, we should eschew modern dietary habits and return to our roots.
Well, while ancient humans may not have been as healthy as some people think, the idea still has an immediate appeal. With disease exploding over the last century, something is deeply wrong with how modern humans are living, and diet is a primary culprit.
But is a return to the Stone Age the answer?
Well, the first problem with the theory of the Paleo Diet is the assumption that just because a dietary behavior or method of food processing is more recent, it’s automatically worse than the ancestral model.
Our prehistoric forebears had one thing in mind, every day: survival. They ate whatever they could get their hands on, including each other sometimes. (Uh, is human flesh Paleo-approved?) The point is their food choices weren’t always optimal, and if we were transported back to the Paleolithic times, we would be smart to decline a dinner invitation.
Although it doesn’t have much bearing on the actual dietary protocols themselves, I found it slightly ironic that the Paleolithic humans didn’t follow the Paleo Diet.
The historical angle of the Paleo Diet is based on a set of findings by its founder, Dr. Loren Cordain, and other researchers, which proposes that humans during the Paleolithic era were primarily hunter-gatherers, with an emphasis on the hunting.
This paper is an important piece of the scientific underpinnings of the Paleo Diet, and is, in turn, based on the flawed Ethnographic Atlas, a database on many cultural aspects of 1167 societies.
Primate ecologist Katherine Milton wrote an insightful paper on the matter, and here are a few highlights:
- The sources of data for the Ethnographic Atlas are mostly from the 20th century. We’ve since learned that some societies coded as hunter-gathers weren’t exclusively hunter-gatherers.
- Some of the authors that helped compiled the Atlas were sloppy in their data collection. Furthermore, most of the researchers were male, and much of the collection and processing done by women was likely mis- or underreported.
- The hunter-gatherers included in the Atlas were modern-day humans, not people living in the primitive conditions of our distant past. The wide variety of dietary behaviors seen don’t fall into a nice pattern that we can emulate. Furthermore, most of the hunter-gatherer societies lived off vegetable foods–an emphasis on hunting was rare.
These critiques have been borne out by other studies.
- A study conducted by the Max Planck Institute for Evolutionary Anthropology reported that the diet our early human ancestors, dating from about 2 million years ago, consisted almost exclusively of leaves, fruit, wood, and bark–similar to chimpanzees today.
- A study conducted by the University of Calgary found that the diet of ancient Africans (going back as far as 105,000 years) may have been based on the cereal grass sorghum. (Remember, grains are a big no-no in Paleo ideology).
- Research conducted by the Center for Advanced Study of Hominid Paleobiology shows that the European Neanderthals ate starchy grains, nearly 44,000 years ago.
- Researchers from the Italian Institute of Prehistory and Early History also found that grains were regularly eaten by our Paleolithic ancestors. Their findings suggest that processing vegetables and starches, and possibly even grinding them into flour, goes back as far as 30,000 years in Europe.
So, while the “eat like our ancestors” pitch makes for good marketing, the reality is actually doing it doesn’t equate to the Paleo Diet as we know it.
Now, even if that strips the Paleo Diet of a bit of its scientific legitimacy and luster, it doesn’t mean it’s not a healthy way to eat.
The new question, then, becomes:
Even if our ancient ancestors weren’t “Paleo,” is the diet worthwhile nonetheless?
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Here’s the premise of the Paleo Diet, as stated by its founder, Dr. Loren Cordain:
“With readily available modern foods, The Paleo Diet mimics the types of foods every single person on the planet ate prior to the Agricultural Revolution (a mere 333 generations ago). These foods (fresh fruits, vegetables, meats, and seafood) are high in the beneficial nutrients (soluble fiber, antioxidant vitamins, phytochemicals, omega-3 and monounsaturated fats, and low-glycemic carbohydrates) that promote good health and are low in the foods and nutrients (refined sugars and grains, trans fats, salt, high-glycemic carbohydrates, and processed foods) that frequently may cause weight gain, cardiovascular disease, diabetes, and numerous other health problems. The Paleo Diet encourages dieters to replace dairy and grain products with fresh fruits and vegetables – foods that are more nutritious than whole grains or dairy products.”
Despite his revisionist version of how our ancestors ate, it seems like a pretty sensible way to eat, no?
“But wait!” You might be thinking. “Won’t eating a bunch of saturated fat cause your heart to explode?”
The reality is there are quite a few good things that can be said about following the Paleo Diet:
- It’s a high-protein diet, which is quite healthy.
- It emphasizes lean, and not fatty, meats, which is an effective way to control caloric intake and prevent an imbalance between omega 3 and omega 6 fatty acid intake.
- It also excludes processed meats, which pose health risks.
- It includes a lot of nutritious veggies and fruits, which decreases the risk of various diseases such as cardiovascular disease, stroke, type 2 diabetes, and cancer.
- It emphasizes a higher intake of omega 3 fatty acids, which provides a wide variety of health benefits such as reduced blood pressure; reduced risk of kidney and cardiovascular disease, as well as risk of stroke and metabolic syndrome; improved cognitive function; and more.
- It excludes added sugars, which function as “empty calories.” Diets high in added sugars are often deficient in various micronutrients, because the foods high in such sugars usually have little nutritious value.
- It excludes high-glycemic carbohydrates, which, if eaten regularly and in large enough quantities, can increase the risk of cardiovascular disease and diabetes.
- It excludes trans fats, which increase the risk of cardiovascular disease, and induce insulin resistance.
There’s no question: the Paleo Diet is a healthy way to eat, and is supported by peer-reviewed literature.
A study conducted by the University of California found that compared to the subjects’ normal (poor) dietary habits, the Paleo Diet improved blood pressure, glucose tolerance, insulin sensitivity, and lipid profiles.
Another study, conducted by the University of Lund, found that the Paleo Diet was better for type 2 diabetics than a traditional “diabetes diet” in terms of improving glycemic control (the body’s ability to regulate blood sugar levels) and cardiovascular risk factors.
So, clearly the Paleo Diet has its merits. But the problems with the Paleo Diet begin when we dive deeper into its dogma.
The first big problem with Paleo is the stance that one singular way of eating is superior to all others.
The longest living populations on the planet are the peoples of Okinawa, Japan; Sardinia, Italy; Nicoya, Costa Rica; Ikaria, Greece; and the Seventh Day Adventists in Loma Linda, California–the “Blue Zones,” as these geographical locations have been labeled.
“…dietary patterns associated with longevity emphasize fruits and vegetables and are reduced in saturated fat, meats, refined grains, sweets, and full-fat dairy products.”
“Equally notable is the wide variation in other aspects of healthy diets, particularly macronutrient intake. Traditional Okinawan diets provide ≥90% of calories from carbohydrate (predominantly from vegetables), whereas the traditional Mediterranean diet provides >40% of calories from fat, mostly monounsaturated and polyunsaturated fat.”
The point is while it’s tempting to conclude that the diets of “Blue Zoners” are the best way to achieve optimal health, it would be erroneous to do so. There are too many other non-dietary factors that contribute to longevity. The same can be said for the Paleo Diet.
The second big problem with the Paleo ideology is not what it has you eat, but what it has you avoid.
By following the Paleo Diet strictly, you miss out on potential benefits from foods like dairy, legumes, and whole grains, and the reasons given for avoiding such foods are scientifically flawed.
- Dairy products are a good source of calcium, protein, and vitamin D. Potassium, magnesium, zinc, and several other vitamins. Research has shown that dairy can improve bone health, muscle mass and strength, and even weight management. Now, lactose intolerance is fairly prevalent and people can get these nutrients in other ways, but for those that do fine with dairy, it’s a highly nutritious food.
It’s worth noting that I’m a bit concerned with the quality of run-of-the-mill dairy here in the States due to the poor health of many of the dairy cows and the artificial hormones many are given that find their way into the milk. These issues aren’t part of the Paleo argument against dairy, though, which is simply that our ancient ancestors didn’t eat dairy so neither should we.
- Whole grains have been shown to reduce inflammation in the body and decrease the risk of cardiovascular disease, type 2 diabetes, and cancer, and even reduce mortality.
Paleo gurus will often say that whole grains damage the intestines, but there simply isn’t any reliable, in vivo (in living organisms) research available to support these claims.
Now, as with dairy, some people don’t do well with grains. A true gluten intolerance is much less common than Paleo gurus would have you believe, but it’s out there. And refined grains are not a good replacement for whole grains as they lose many of their nutrients during processing, and have been associated with increased inflammation in the body.
But for those that do fine with whole grains, they are a great source of carbohydrate, various nutrients, and fiber.
- Non-soy legumes have been shown to decrease total and LDL (“bad”) cholesterol levels. They’re also a good source of protein, carbohydrate, and fiber.
Paleo proponents often say you should avoid legumes because they believe our ancestors didn’t eat them, and because they contain antinutrients that interfere with nutrient absorption. While legumes do contain these antinutrients, so do many other foods, and they are reduced by simple processing methods like soaking and cooking.
The bottom line is antinutrients found in whole grains and legumes are not a problem unless your diet is devoid of nutritious foods and horribly imbalanced in terms of macronutrients. Yes, if you mostly eat uncooked whole grains and beans all day, you will have some problems. However, there’s no research to indicate that such antinutrients are a problem at normal intake levels and as a part of a properly balanced diet.
As you can see, while Paleo’s “approved foods” are quite alright, its blacklisted foods just don’t make sense.
One last little point I would like to address is the claims that you can lose weight on the Paleo Diet without having to count calories.
This is a bit misleading because the fact is weight loss requires a caloric deficit, regardless of how you get there in terms of actual food eaten.
Don’t believe me?
Check out this professor that lost 27 pounds by eating junk foods like Twinkies, Little Debbie snacks, and Doritos. How did he do that? Simply by regulating the AMOUNT of food he was eating (total daily calories), not WHAT.
I’ve worked with scores of people that weren’t losing weight on the Paleo Diet simply because they had no concept of how many calories they were actually eating.
Eating a healthy, low-carb diet doesn’t mean you automatically lose weight–you have to maintain a caloric deficit.
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While its historical foundations are flawed, the Paleo Diet has a lot going for it. It’s a hell of a lot healthier than the average person’s diet, and you can derive many health benefits from it.
The mistake many people make with Paleo is accepting its extremes, which simply aren’t scientifically defensible.
I actually eat fairly Paleo, because I enjoy meats, fruits, and vegetables. I also enjoy grains like rice, quinoa, and whole-grain pasta and bread, as well as a bit of dairy and legumes here and there.
Unsurprisingly, some of less dogmatic and better informed Paleo gurus like Mark Sisson advocate this “80/20” approach. That is, you mostly eat meats, veggies, fish, fruit, and nuts, but you include limited amounts of dairy, grains, legumes, and other “non-Paleo” foods as needed or desired.
What are your thoughts on the Paleo Diet? Have anything else you’d like to add? Let me know in the comments below!
+ Scientific References
- Hotz, C., & Gibson, R. S. (2007). Traditional food-processing and preparation practices to enhance the bioavailability of micronutrients in plant-based diets. Journal of Nutrition, 137(4), 1097–1100. https://doi.org/10.1093/jn/137.4.1097
- Gilani, G. S., Xiao, C. W., & Cockell, K. A. (2012). Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality. British Journal of Nutrition, 108(SUPPL. 2). https://doi.org/10.1017/S0007114512002371
- Bazzano, L. A., Thompson, A. M., Tees, M. T., Nguyen, C. H., & Winham, D. M. (2011). Non-soy legume consumption lowers cholesterol levels: A meta-analysis of randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases, 21(2), 94–103. https://doi.org/10.1016/j.numecd.2009.08.012
- Jacobs, D. R., Andersen, L. F., & Blomhoff, R. (2007). Whole-grain consumption is associated with a reduced risk of noncardiovascular, noncancer death attributed to inflammatory diseases in the Iowa Women’s Health Study. American Journal of Clinical Nutrition, 85(6), 1606–1614. https://doi.org/10.1093/ajcn/85.6.1606
- Jacobs, D. R., Marquart, L., Slavin, J., & Kushi, L. H. (1998). Whole-grain intake and cancer: An expanded review and meta-analysis. In Nutrition and Cancer (Vol. 30, Issue 2, pp. 85–96). Routledge. https://doi.org/10.1080/01635589809514647
- De Munter, J. S. L., Hu, F. B., Spiegelman, D., Franz, M., & Van Dam, R. M. (2007). Whole grain, bran, and germ intake and risk of type 2 diabetes: A prospective cohort study and systematic review. In PLoS Medicine (Vol. 4, Issue 8, pp. 1385–1395). PLoS Med. https://doi.org/10.1371/journal.pmed.0040261
- Katcher, H. I., Legro, R. S., Kunselman, A. R., Gillies, P. J., Demers, L. M., Bagshaw, D. M., & Kris-Etherton, P. M. (2008). The effects of a whole grain-enriched hypocaloric diet on cardiovascular disease risk factors in men and women with metabolic syndrome. American Journal of Clinical Nutrition, 87(1), 79–90. https://doi.org/10.1093/ajcn/87.1.79
- Masters, R. C., Liese, A. D., Haffner, S. M., Wagenknecht, L. E., & Hanley, A. J. (2010). Whole and refined grain intakes are related to inflammatory protein concentrations in human plasma. Journal of Nutrition, 140(3), 587–594. https://doi.org/10.3945/jn.109.116640
- Van Loan, M. (2009). The role of dairy foods and dietary calcium in weight management. Journal of the American College of Nutrition, 28, 120S-129S. https://doi.org/10.1080/07315724.2009.10719805
- Josse, A. R., Tang, J. E., Tarnopolsky, M. A., & Phillips, S. M. (2010). Body composition and strength changes in women with milk and resistance exercise. Medicine and Science in Sports and Exercise, 42(6), 1122–1130. https://doi.org/10.1249/MSS.0b013e3181c854f6
- Heaney, R. P. (2009). Dairy and bone health. Journal of the American College of Nutrition, 28, 82S-90S. https://doi.org/10.1080/07315724.2009.10719808
- Appel, L. J. (2008). Editorial: Dietary patterns and longevity expanding the blue zones. In Circulation (Vol. 118, Issue 3, pp. 214–215). Circulation. https://doi.org/10.1161/CIRCULATIONAHA.108.788497
- Lindeberg, S., Jönsson, T., Granfeldt, Y., Borgstrand, E., Soffman, J., Sjöström, K., & Ahrén, B. (2007). A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia, 50(9), 1795–1807. https://doi.org/10.1007/s00125-007-0716-y
- Frassetto, L. A., Schloetter, M., Mietus-Synder, M., Morris, R. C., & Sebastian, A. (2009). Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. European Journal of Clinical Nutrition, 63(8), 947–955. https://doi.org/10.1038/ejcn.2009.4
- Micha, R., & Mozaffarian, D. (2008). Trans fatty acids: Effects on cardiometabolic health and implications for policy. Prostaglandins Leukotrienes and Essential Fatty Acids, 79(3–5), 147–152. https://doi.org/10.1016/j.plefa.2008.09.008
- Barclay, A. W., Petocz, P., McMillan-Price, J., Flood, V. M., Prvan, T., Mitchell, P., & Brand-Miller, J. C. (2008). Glycemic index, glycemic load, and chronic disease risk - A metaanalysis of observational studies. American Journal of Clinical Nutrition, 87(3), 627–637. https://doi.org/10.1093/ajcn/87.3.627
- Gibson, S. A. (2007). Dietary sugars intake and micronutrient adequacy: A systematic review of the evidence. In Nutrition Research Reviews (Vol. 20, Issue 2, pp. 121–131). Nutr Res Rev. https://doi.org/10.1017/S0954422407797846
- Muldoon, M. F., Ryan, C. M., Sheu, L., Yao, J. K., Conklin, S. M., & Manuck, S. B. (2010). Serum phospholipid docosahexaenonic acid is associated with cognitive functioning during middle adulthood. Journal of Nutrition, 140(4), 848–853. https://doi.org/10.3945/jn.109.119578
- Huang, T., Bhulaidok, S., Cai, Z., Xu, T., Xu, F., Wahlqvist, M. L., & Li, D. (2010). Plasma phospholipids n-3 polyunsaturated fatty acid is associated with metabolic syndrome. Molecular Nutrition and Food Research, 54(11), 1628–1635. https://doi.org/10.1002/mnfr.201000025
- He, K., Rimm, E. B., Merchant, A., Rosner, B. A., Stampfer, M. J., Willett, W. C., & Ascherio, A. (2002). Fish consumption and risk of stroke in men. Journal of the American Medical Association, 288(24), 3130–3136. https://doi.org/10.1001/jama.288.24.3130
- Simopoulos, A. P. (2008). The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. In Experimental Biology and Medicine (Vol. 233, Issue 6, pp. 674–688). Exp Biol Med (Maywood). https://doi.org/10.3181/0711-MR-311
- F., L., M., M., F., P., S., M., C., R., P., C., S., B., & L., F. (2009). Omega-3 and Renal Function in Older Adults. Current Pharmaceutical Design, 15(36), 4149–4156. https://doi.org/10.2174/138161209789909719
- Ramel, A., Martinez, J. A., Kiely, M., Bandarra, N. M., & Thorsdottir, I. (2010). Moderate consumption of fatty fish reduces diastolic blood pressure in overweight and obese European young adults during energy restriction. Nutrition, 26(2), 168–174. https://doi.org/10.1016/j.nut.2009.04.002
- Hamer, M., & Chida, Y. (2007). Intake of fruit, vegetables, and antioxidants and risk of type 2 diabetes: Systematic review and meta-analysis. Journal of Hypertension, 25(12), 2361–2369. https://doi.org/10.1097/HJH.0b013e3282efc214
- He, F. J., Nowson, C. A., & MacGregor, G. A. (2006). Fruit and vegetable consumption and stroke: Meta-analysis of cohort studies. Lancet, 367(9507), 320–326. https://doi.org/10.1016/S0140-6736(06)68069-0
- He, F. J., Nowson, C. A., Lucas, M., & MacGregor, G. A. (2007). Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: Meta-analysis of cohort studies. Journal of Human Hypertension, 21(9), 717–728. https://doi.org/10.1038/sj.jhh.1002212
- Rohrmann, S., Overvad, K., Bueno-de-Mesquita, H. B., Jakobsen, M. U., Egeberg, R., Tjønneland, A., Nailler, L., Boutron-Ruault, M. C., Clavel-Chapelon, F., Krogh, V., Palli, D., Panico, S., Tumino, R., Ricceri, F., Bergmann, M. M., Boeing, H., Li, K., Kaaks, R., Khaw, K. T., … Linseisen, and J. (2013). Meat consumption and mortality - results from the European Prospective Investigation into Cancer and Nutrition. BMC Medicine, 11(1), 63. https://doi.org/10.1186/1741-7015-11-63
- Westerterp-Plantenga, M. S. (2003). The significance of protein in food intake and body weight regulation. In Current Opinion in Clinical Nutrition and Metabolic Care (Vol. 6, Issue 6, pp. 635–638). Curr Opin Clin Nutr Metab Care. https://doi.org/10.1097/00075197-200311000-00005
- Gershuni, V. M. (2018). Saturated Fat: Part of a Healthy Diet. In Current Nutrition Reports (Vol. 7, Issue 3, pp. 85–96). Current Science Inc. https://doi.org/10.1007/s13668-018-0238-x
- Siri-Tarino, P. W., Sun, Q., Hu, F. B., & Krauss, R. M. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, 91(3), 535–546. https://doi.org/10.3945/ajcn.2009.27725
- Revedin, A., Aranguren, B., Becattini, R., Longo, L., Marconi, E., Lippi, M. M., Skakun, N., Sinitsyn, A., Spiridonova, E., & Svobodah, J. (2010). Thirty thousand-year-old evidence of plant food processing. Proceedings of the National Academy of Sciences of the United States of America, 107(44), 18815–18819. https://doi.org/10.1073/pnas.1006993107
- Henry, A. G., Brooks, A. S., & Piperno, D. R. (2011). Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). Proceedings of the National Academy of Sciences of the United States of America, 108(2), 486–491. https://doi.org/10.1073/pnas.1016868108
- Mercader, J. (2009). Mozambican grass seed consumption during the middle stone age. Science, 326(5960), 1680–1683. https://doi.org/10.1126/science.1173966
- Henry, A. G., Ungar, P. S., Passey, B. H., Sponheimer, M., Rossouw, L., Bamford, M., Sandberg, P., De Ruiter, D. J., & Berger, L. (2012). The diet of australopithecus sediba. Nature, 487(7405), 90–93. https://doi.org/10.1038/nature11185
- Milton, K. (2000). Hunter-gatherer diets - A different perspective. In American Journal of Clinical Nutrition (Vol. 71, Issue 3, pp. 665–667). American Society for Nutrition. https://doi.org/10.1093/ajcn/71.3.665
- Murdock, G. P. (1967). Ethnographic Atlas: A Summary. Ethnology, 6(2), 109. https://doi.org/10.2307/3772751
- Cordain, L., Miller, J. B., Eaton, S. B., Mann, N., Holt, S. H. A., & Speth, J. D. (2000). Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition, 71(3), 682–692. https://doi.org/10.1093/ajcn/71.3.682