Saturday, May 18, 2013

What Exactly is the Paleo Diet?

The Paleo Diet (sometimes called The Caveman Diet) has become very popular lately. Those who practice the diet swear that it improves their health, increases energy, improves insulin sensitivity, and helps shed unwanted pounds. (1) But others believe that the diet's insistence on quality local or organic foods is all just elitist foodie nonsense. (2) Who's right?

In this post, I'll explore the basic Paleo diet idea, what evidence may support its main arguments, and how far the diet itself as has evolved. Ultimately I'll answer the most important question: Is it just a fad?

Paleo Diet 101
The basic idea behind the Paleo(lithic) diet is to simply eat the foods that humans evolved to eat. Because it is believed that human growth, development, and health were calibrated to the various wild plant, animal, and insect foods available during the Paleolithic Era (the time period between 2.6 million to about 10,000 years ago), a person should experience optimal health by primarily consuming these foods. (3)

However, if a person deviates from this diet, chronic degenerative disease (e.g., diabetes, heart disease, cancer, obesity) will follow. In fact, creators of the diet blame the recent rise in these once rare degenerative diseases on a fundamental shift in the quality of the modern diet from fresh whole foods to new agricultural foods (e.g., grains, legumes, dairy) within the last 10,000 years. (4)

Consequently, since it is also believed that today's humans are genetically similar to Paleolithic humans, a person should be able to reduce--or eliminate--any chronic diseases they might have by going back to eating a Paleo-like diet that the human body is designed to eat (comprised primarily of fresh and whole plant and animal foods). (5)

Is the Paleo Diet a Fad?
When it comes to understanding whether or not a Paleo-like diet is faddish, I like looking at human evolution using a human calendar. (6) If our evolution spans 365 million years, then:
  • January 1: Amphibian ancestor
  • March 5: Reptile ancestor
  • June 10: Early Mammal
  • July 20: America starts to separate from Europe and Africa
  • October 28: Primate ancestor
  • Christmas Eve: Bipedal Ancestor (hominid)
  • New Years Eve:
    • 19:30:00 - Homo sapiens (modern humans)
    • 21:30:00 - Some of us leave Africa
    • 22:45:00 - Some of us go to New Guinea
    • 23:00:00 - Some of us go to Europe
    • 23:40:00 - And even Scandinavia
    • 23:45:00 - Agriculture starts in Middle East
    • 23:52:00 - Agriculture starts in Scandinavia
    • 23:53:00 - The Ice Man dies in the Alps
    • 23:59:00 - The Black Death (the European pandemic of plague)
    • 23:59:50 - Cardiovascular disease appears
(Note: 1 day -1 million years; 1 hour = 41700 years; 1 minute = 694 years; 1 second = 11.5 years)

As I will discuss in a later section, humans were likely eating a diet comprised of locally-sourced meats, eggs, insects, vegetables, root vegetables, and fruit since sometime just before Christmas Eve (or about 2.6 million years ago). By contrast, certain humans have only been exposed to a grain-based Neolithic diet for about 15 minutes (about 10,000 years).

Americans (and much of Europe) have only enjoyed a more industrialized diet for about 8 seconds (or about 92 years). And the low-fat, low-cholesterol, and/or low-carb diets that are popular now have been utilized for only about 3 seconds (or about 30 years).

So, if we look at what the human diet should be from an evolutionary perspective, it seems that the basic belief that humans should eat fresh animal and plant foods is not faddish at all. However, as I will talk about throughout this post, there are certain faddish aspects to the Paleo Diet that should be better understood or avoided completely (e.g., Low/Zero-Carb, fear of all things Neolithic).

How Well is Paleo Supported?
There is a lot of evidence showing that individuals who switch from eating the Standard American Diet (SAD) to a more Paleo-like diet can improve most markers for health (e.g., glucose sensitivity, blood cholesterol, blood pressure, waist circumference) in as little as 10 days. (1,7,8) There is also tons of anecdotal evidence showing a Paleo-like diet permanently improving health and reducing excess body weight. (9,10)

Early research into what we would call the Paleo Diet started during the early 20th century when paleopathologists started evaluating human skeletal evidence to better understand the past health of our human ancestors. They discovered that Paleolithic humans were much taller, stronger, and healthier than Neolithic humans, implying better nutrition and health. (3,11) Anthropologists also estimated that Paleolithic humans ate a wide variety of both animal and plant foods. (12,13)

Other researchers started traveling the world to observe the health of humans that didn't consume an industrialized diet filled with white sugar, white flour, vegetable oils, and canned foods. No matter where these researchers went, they found that if humans ate their traditional diets they were also exceptionally healthy. Those who deviated from their traditional diets and embraced a more industrialized one quickly developed degenerative diseases. (3,8,14)

The four Swiss children on the left were raised on a traditional diet of fresh dairy and rye, resulting in exceptional facial development with almost no tooth decay (despite not having a local dentist or brushing their teeth). The four Swiss children on the right were exposed to a modernized diet (which, in the 1930s, included white sugar and flour, jams and jellies, and canned and other processed foods) experienced rampant tooth decay, despite having access to local dentists. Source

Here are just a few examples of what these researchers found:
  • In 1935, Weston A. Price observed the Masai tribe in Kenya, Africa. The male Masai warriors were exceptionally tall (some taller than 6 feet, which unusually tall for hunter-gatherers), very fit, and had no trace of degenerative diseases. These men lived primarily on raw cow's milk, meat, and blood, as well as vegetables and fruit. No modern foods (e.g., refined sugar, white flour, or canned foods) were consumed while these men were serving as warriors. (15)
  • In 1938, G. T. Wrench described the Hunza who lived in what is now Pakistan. They were exceptionally healthy, known for their superior fitness and endurance, were long lived, and suffered from no degenerative diseases. They ate whole plant and animal foods, including ancient wheat, lots of fruit (both fresh and dried), and raw milk. They didn't consume any modern foods. (16)
  • In 1989, researcher Staffan Lindeberg studied the Kitavans of Papua New Guinea. These traditional humans were virtually free of degenerative diseases, long lived, and exhibited exceptional physical and mental health. They ate whole plant and animal foods, as well as a lot of saturated fat and fresh fruit. Modern foods comprised no more than 2% of their total daily calories. They also had a near universal love of cigarettes. (6)

Animal experiments conducted during the 1930s also showed that you could make perfectly healthy animals very sick with degenerative diseases by simply switching their fresh chow with highly-processed foods. These experiments also showed that this diet-induced poor health could be passed forward to future generations: If these processed foods were fed to these animals over multiple generations, these diseases got progressively worse with each generation, eventually resulting in complete infertility. (17)

Clearly, something was missing from these highly-processed foods that was present in fresh foods. This was later found to be essential nutrients that eventually became known as vitamins and minerals. (18)

"Effect of different wheat products on rats. Left: whole wheat. Center: white flour. Right: bran and middlings mixture. The graphs record actual amount of indicated minerals present, as milligrams per cent. Only the rats on the whole wheat developed normally without tooth decay. Those on white flour had tooth decay, were underweight, had skin infections and were irritable. They did not reproduce. The third group were undersize. The balance of the ration was the same for all." Source.

These observations (and many more) eventually led to the modern idea of what we now call the Paleo Diet, which got started in the 1970s by gastroenterologist Walter L. Voegtlin. However, this early diet was low-carb and largely carnivorous. (19)

Other researchers updated the Paleo diet in the 1980s, but this version was a bizarre mix of what Paleolithic humans were thought to have eaten and the low-animal-fat/cholesterol beliefs that were popular at that time. It wasn't until the late 1990s that the Paleo Diet started to look similar to what it is today. (20)

What Exactly Did Paleolithic Humans Eat?
Because humans were scattered throughout the world (just like modern humans today), each geographical location had its own unique mix of available foods. This forced traveling humans to figure out how to become healthy on a diet that could have been high-carb, high-protein, and/or high-fat.

This table represents the range of estimated macro-nutrients consumed by Paleolithic hunter-gatherers in different parts of the world. 

For much of the Paleolithic, humans ate fruits and vegetables, just like our chimp cousins. But some archaeological evidence suggest that around 2.6 million years ago humans started eating fatty and nutrient-dense animal foods (especially brain and marrow). This switch to animal foods also likely fueled the growth of the human brain. (21)

Bone surface modifications implying meat eating by humans. (A) Cut marks on a small bovid metatarsal; (B) hammerstone notches on a medium-sized bovid humerus; (C) percussion pit and striae on a mammal limb bone shaft fragment; (D) cut marks on a small bovid femur; 1 mm in the panel (D) close-up. Source.

This suggestive evidence can be supported by the extremely simplified human digestive system that became more carnivore-like, losing much of the chimpanzee machinery needed to digest raw fruit and plants, as well as the peculiar coincidence of animal extinctions coinciding with human expansion across the globe. (22,23)

But humans weren't simply meat, fruit, and vegetable eaters: They eventually evolved the ability to digest starchy tubers and root vegetables (similar to modern taro and potatoes). Evidence exists that shows Neanderthals eating starchy root vegetables around 250,000 years ago and humans eating starchy tubers ground as flour about 30,000 years ago. Humans also evolved more copies of a gene that makes salivary amylase, which digests starch. (3) Interestingly, dogs (but not wolves) also evolved the ability to digest starch, likely because they were eating what humans were eating. (24

The Paleo Diet Today
Personally, I think that the greatest power of the Paleo Diet is not so much what these humans ate, but what they didn't. Humans in the Paleolithic Era couldn't have eaten much refined sugar or white flour and could not have had any modern high-gluten wheat, high-omega-6 vegetable oils, genetically modified (GM) produce, unfermented soy, pasteurized/homogenized dairy, or chemically taste-enhanced/preserved prepared foods. They also couldn't have eaten prepared foods like microwavable dinners, candy bars, chips, pseudo-milk (e.g., soy, almond), soda, or most of the things that now come out of a box, bag, or can.

This means that to eat Paleo you should be generally cautious of the foods that humans started eating within the last 10,000 years (e.g., wheat, corn, rice, legumes, fermented soy, and dairy) and eat more of the fresh, whole, plant and animal foods eaten by Paleolithic human populations.

As I will elaborate further in another post, you should also avoid industrialized foods created within the last 150 years (e.g., refined high-fructose sweeteners, modern wheat, vegetable oils, margarine). It is very likely that these new foods are driving most of the degenerative diseases plaguing Americans--and other industrialized nations--today.

Paleo and Saturated Fats
When it comes to dietary saturated fats, the original diet believed that saturated fat could be linked to heart disease. This view has since changed. Why? One reason comes from contemporary hunter-gatherers. Some of them consume up to 50% of their total fat calories in saturated form (usually coconut oil, which is the most saturated fat you can eat) and they have zero heart disease (so long as the they don't eat industrialized foods). There is also very little scientific evidence to link dietary saturated fats to heart disease.

Paleo and Low-Carb
Many people falsely believe that the Paleo diet is low-carb. As I mentioned earlier, there is good evidence that humans evolved to digest carbohydrates due to their exposure to root vegetables early during our evolution. There are also contemporary hunter-gatherers who eat up to 70% of their calories as carbohydrates without any negative health effects (in fact, they are exceptionally healthy, experiencing virtually zero degenerative disease). (6)

This is not to say that all carbohydrates are healthy (you should seriously reduce your intake of white sugar and flour), I'm just saying that not all carbs are bad. Essentially, whole sources of starches and sugars are better tolerated than highly-refined sources, with the dosage making a carbohydrate either healthful or harmful. (3,25,26) And if you are suffering from chronic stress, or are inactive, then carbohydrates may cause fat weight gain.

Is Raw Milk Paleo?
Because there is some evidence that nomadic Paleolithic humans would follow herds of wild ruminants for their milk, quality raw milk from cows fed green grass should be fine to drink. On the other hand, modern pasteurized milk from cows trapped in containment dairies should be avoided. (27)

Other dairy products, however, are fine to eat (e.g., organic butter and cream).

Paleo and Industrial Produce
Industrial produce is any meat or plant product that is grown, harvested, and delivered using industrial methods (as opposed to traditional methods). Because this industrial process favors speed and efficiency over nutrient preservation, and usually travels hundreds or thousands of miles to reach the consumer, industrial produce tends to be less nutritious than organic or local produce. (28,29)

But that doesn't mean that industrial produce is absolute trash. These foods are much healthier than the highly-processed and engineered foods that many Americans eat today. If you can't get access to local or organic foods, then it is perfectly fine to use industrial produce as a basis for your foods. You just may need to pay closer attention to your vitamin and mineral supplementation.

Paleo and Frozen and Canned Foods
Obviously, there were no canned or frozen foods in the Paleolithic. And, depending on how it is processed, canned and frozen foods can lose many of it nutrients. But does that mean that you should avoid all canned foods? Not necessarily. Just eat canned and frozen foods occasionally.

Is Cheating Allowed?
Many Paleo diet neophytes believe that eating anything from the Neolithic (e.g., refined sugar, milk, processed foods, vegetable oils, soy) will destroy their health. This isn't necessarily true. Fortunately, because the human body is such a durable machine, occasional indulgence in what I call the 7 Deadly Foods should not be harmful (although you might feel like crap afterwards). However, you have to eat a nutritious diet most of the time to remain healthy.

The reason I don't want you to worry about occasional indulgence in convenience foods is because a lot of stress can come from obsessing about eating a purely clean diet. If you worry about it all the time then you can actually create a chronic stress response. And as I've talked about before, chronic stress has a lot of unpleasant side effects (e.g., abdominal obesity, insulin resistance, muscle wasting).

So, as long as you are eating a clean diet 80-90 percent of the time, you should be fine. This means that you can occasionally have a piece of cake at a birthday party, enjoy some sweetened deserts during the holidays, or eat some bread when you go out to dinner (unless you are gluten sensitive or intolerant).

The Faileo Diet?
When someone tries the Paleo Diet and fails miserably, they likely did some or all of the following:
  • Used a very low-fat or low-carb approach to Paleo.
  • Avoided saturated fats and cholesterol in their foods.
  • Used vegetable oils instead of animal oils.
  • Only ate vegetables and fruit (and little to no animal products).
  • Only ate meat (and little to no vegetables and fruit).
This approach to Paleo is known as the Faileo Diet. The Faileo Diet is nothing more than a contemporary spin on the Paleo Diet idea. For a perfect example of a Faileo Diet, check out Dr. Oz's thoroughly unbelievable Paleo diet plan, which is very low in protein (10% of total calories!), against animal foods, full of modern soy and grains, and brimming with modern high-omega-6 oils. What's Paleo about that?

Which Paleo Diet is Best?
Because scientists and diet gurus have embraced the basic Paleo Diet premise in different ways, it has gone through an evolution itself. As a result, the modern concept of the Paleo Diet has changed quite a bit and not all Paleo gurus are on the same page. So who's preaching the right version of this diet?

To answer this questions, I think it's helpful to see how the Paleo Diet has changed over the years. From my perspective, this diet has gone through two main evolutionary stages: Paleo Diet 1.0 (low-carb) and Paleo Diet 2.0 (which isn't particularly low-carb, but does believe that a high intake of refined carbohydrates can cause health problems). Here's a quick breakdown:
  • Paleo 1.0 (original theory): The basic theory says that you should primarily eat naturally-raised/grown whole animal and plant foods. You should also avoid modern foods like grains, legumes, dairy, and foods high in chemical additives, carbohydrates, cholesterol, and fat (especially saturated fats).
  • Paleo 1.5 (The Paleo SolutionThe Paleo DietThe Primal Blueprint): The Paleo Diet idea was updated to acknowledge that saturated fats and cholesterol are actually very healthy and unlikely to cause heart disease. This meant that you can now eat animal fats like butter and dairy cream, as well as obtain more fat from your meats, but carbs are still seen as inherently unhealthy. This version also advises you to avoid chemical additives, wheat, fructose, high-omega-6 oils, trans fats, soy, milk, cheese, and foods with a high glycemic index (GI).
  • Paleo 2.0 (Perfect Health Diet): The Paleo Diet moved in an exciting new direction with the publication of the Perfect Health Diet in 2010, which created the concept of "safe starches." Essentially, it embraced the main Paleo argument of eating whole animal and plant foods, but argued that a moderate amount of some non-toxic starches (e.g., potatoes, white rice, taro) were very good for human health.
  • Paleo 2.5 (Rapid PTChris Kresser): This version represents the cutting edge of the Paleo Diet. It still embraces the essence of Paleo 2.0, but believes that quality raw dairy and/or properly prepared legumes can be healthy.

With these different flavors of Paleo, which should you choose? I believe that the more carbohydrate-restrictive Paleo 1.0 may benefit those struggling to lose weight, suffering from certain metabolic diseases, or are largely inactive. However, anyone with a healthy metabolism who also engages in high-intensity exercise will need the safe carbohydrates allowed in Paleo 2.0.

And given the Paleo community's insatiable need to know what an actual healthy diet is, Paleo 3.0 (the best of both Paleolithic and Neolithic diets) is an inevitability. Of course, if the Paleo diet evolves that far, then it will no longer technically be a Paleolithic diet, but a modern one that maximizes human health with all healthful foods, no matter which era they come from.

So, is the Paleo Diet just a faddish diet that will disappear in a couple of years? I don't think so.

It seems obvious to me that it is not normal for humans to suffer from most of the degenerative diseases plaguing industrialized nations today (e.g., overweight, high blood pressure, insulin resistance, chronic infections, cancer, heart disease). It also seems obvious that the recent rise of these diseases is partially connected to the recent dietary shift from fresh, whole, animal and plant foods to a more refined, toxic, and nutrient devoid industrialized one.

The modern answer to these degenerative diseases has been drugs, which don't really cure the disease, it simply manages the symptoms. This is a very costly and ineffective way to manage a person's illness. Instead, I believe that before you decide to take powerful drugs (or utilize invasive surgeries), you should first try to heal yourself with fresh, whole, nourishing foods. And a Paleo-like diet seems to be a good diet to try.

There is nothing magical about this diet. It simply provides the non-toxic foods that the human body expects. Once the body is provided the essential and non-essential nutrients that allow it to function properly, degenerative diseases should stop progressing or disappear altogether (without the need for drugs or surgery).

Also, if a Paleo-like diet is consumed throughout a person's life, then they should (theoretically) never develop degenerative diseases in the first place, allowing them to live a long and disease-free life.

Not convinced? Pick a Paleo Diet from the previous section and try it out for 30 days. Although the first couple of days might be a little rough, after your body gets used to eating less refined, chemically-enhanced foods you may find that you have more energy, less brain fog, fewer extra fat pounds, and improved overall well-being. And while all diets promise this result in the short-term, only a diet that closely matches the diet you evolved to eat can provide these results for the rest of your life.


  1. Thank you for the information. I really appreciate the amount of research and the way it has been presented. I still doubt that most people will be able to follow any of the paleo diets stricktly for the rest of their lives, but certainly it educates us to cut out all the refined junk and processed foods and eat more natural and raw things.

    If you have any information in how to deal with an overactive mind, by way of insomnia then I would be grateful. My mind is like a light swtich that can never be turned off and I constantly struggle to sleep. When I do finally nod off I always have vivid dreams which means that when I wake up, I am exhausted. Its like I have 2 lives! Any help on this topic would be appreciated!
    Thanks Alison

  2. Alison,
    I'm glad that you liked my post. As I'm sure you can tell, I'm a big fan of the Paleo diet, so long as it isn't a low-carb version. But I think that if you take a realistic approach to eating fresh whole foods (e.g., occasional cheating), this diet is relatively easy to stick to for a lifetime.

    Now, if I were to address your problems with insomnia and a hyperactive mind, I’d suggest you do the following:
    • Remove all typically problematic foods for 30 days to see if your problem(s) goes away. If your symptoms go away on the diet, reintroduce the foods you removed from your diet one at a time to which ones are giving you problems. You can try my 30-day diet challenge (, which attempts to find your own personal food sensitivities.
    • Eliminate as many sources of chronic stressors as possible:
    o Chronic infections.
    o Chronic injuries.
    o Emotional worry.
    o Chronic/insufficient exercise.
    o Poor diet.
    o Social disconnection.
    o Unhappy relationships/situations.
    • Avoid all sources of free glutamate (a.k.a., MSG). In some individuals, this chemical acts as an excitotoxin, over-stimulating the brain. Here is a good video that talks about the impact that free glutamate can have on the mind:
    • Try to enforce a calming routine before you go to bed. About an hour before you go to sleep, eliminate all sources of blue light (e.g., computer monitors, TV screens). Start to unwind by reading or taking a shower. If you go to bed and you find that you can’t go to sleep after 5-10 minutes, don’t stay in bed; get up and read something (and don’t watch TV or look at a computer screen). Go to bed when you get sleepy. Eventually, you should start to fall asleep naturally.
    • Get outside more. Exposure to the outside can help to reset your wake/sleep cycle.

    This is as much as I can think of at the moment. Hopefully this helps (and if it does, please let me know)!