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Keto vs Paleo, what should you know?

Last updated: May 10, 2020 at 7:44PM | - Published on: May 2, 2019

Written by Raphael Sirtoli, MSc, Ph.D. (candidate)

Scientifically Reviewed by Sarah Neidler, Ph.D.

Keto and Paleo diets are based around different ideas but they can sometimes be one and the same. keto-paleo (or paleo-keto) diets enjoy a lot of popularity.

A ketogenic diet is any way of eating that leads you to have a certain level of blood ketones, like 1 mmol/L say. A Paleo diet is a little harder to define, but it comes down to foods we evolved eating, like meat and fruit.

Before going into the pros and cons of these two diets, let’s clarify how they are defined:

What’s the keto diet?

keto diet food example

A ketogenic diet puts you into nutritional ketosis. While in ketosis, fat becomes the primary source of energy, and so the body produces more ketone bodies.

The ketogenic state is achieved by a specific distribution of the three macronutrients – protein, fats and carbs. Most importantly, the carb intake has to be kept to a minimum, around < 5-10% of caloric intake. The fat and protein proportion are a bit more flexible but traditionally, 70-80% of calories come from fat and 20-30% from protein.

In theory, it does not matter how to get and stay into ketosis. People following a ketogenic diet may spend a lot of their calories on BulletProof coffee and processed keto snacks rather than invest them into more nourish nutrient-dense foods that also put you in ketosis.

Having said this, whole-food diets are commonplace in the keto world and it’s now common knowledge to avoid the high omega-6 seed oils and trans fats. To learn more about which fats are good for you, check out-out our guide on fats.

What’s the paleo diet?

Paleo diet way of eating

Paleo diets are based on the idea to eat foods resembling those we ate during our evolution. How far back does that go? It could be as long ago as 3.3 million years, 300 – 200 thousand year or even 50,000 years (if you’re talking about anatomically modern humans) [1]. Around 11,000 years ago agriculture started, thus taking the historical paleo diet to its end [2].

The paleo diet can be misunderstood to mean all that is old is good and new bad. Or it can be understood to demonstrate that our complex physiology is best adapted to foods with certain properties our species relied upon during its long history – meat and fish being the best examples.

Of course, the diet differed by geography and season and also changed over hundreds of thousands of years [3]. Hence, there is neither the one paleo diet nor is it possible to mimic such a diet in today’s world accurately.

As a compromise, the modern approach to the Paleo diet tries to eliminate any modern foods with significant evidence of harm the human physiology that did not exist back then – wheat or seed oils being the best examples. This includes industrially manufactured foods like candy (but not traditional salami, for example) as well as dairy products, and grains.

While dairy and grains can be seen as whole or natural foods, we did not eat them in large amounts before the agricultural era if at all. Interestingly, about ⅓ of people worldwide have a (simple) genetic adaptation to consume an evolutionarily novel food like dairy. It’s called lactase persistence. Lactase persistence is a genetic ‘switch’ that remains ON into adulthood.

So dairy is an example of an evolutionarily novel food that is healthy for a large number of people. This suggests that whatever you call your diet, it should include foods provoking healthy metabolic, hormonal and behavioral responses in you over the long-term.

Wheat, on the other hand, is not a food with properties we are adapted to. It cannot be digested whole so it must be turned into flour. This unfortunately not only makes it digestible but also makes it metabolically and hormonally harmful at the very least [4].

The paleo diet is most simply and accurately characterized as the diet high in animal food such as ruminants. This automatically makes it at least mildly, intermittently ketogenic.

However, we likely did rely on plants as fallback foods and in some cases more significantly beyond that. The evidence for high carb paleo diets is only seen in ‘modern’ hunter-gatherer populations which may be best described as horticulturalists rather than strict hunter-gatherers.

What it comes down to is that by avoiding grains/flour, added sugars, and high omega 6 seed oils, it’s hard not to go low carb… Beans and legumes are usually avoided in the paleo diet due to the scarcity of evidence for their use during our evolutionary history and because they have a higher likelihood of causing digestive distress or immune reactions.

That leaves us with carbs from veggies, fruits, and nuts. Of course, a high sugar low fiber modern banana has very little to do with low sugar high fiber berries we may have picked on occasion and in season, so do not think that fruit can do no harm.

What do keto and paleo diets have in common and how do they differ?

Keto vs Paleo cake

Let’s first take a look at what the two diets have in common. Most importantly, they both eliminate grains, but for different reasons. The keto diet eliminates it because it’s loaded with carbs, the paleo diet because it was not eaten by our ancestors.

This includes any kind of grain – whole grains, refined grains, bread, pasta, corn, cereals, rice…Because grains are a staple food in the typical western diet, the two diets already have a crucial factor in common.

The keto and paleo diet also both avoid typical processed foods. These kinds of foods always contain plenty of refined grains and seed oils. Again, they are high in carbs (the keto argument) and not an ancient food (the paleo argument).

However, the keto diet is less strict with food processing. There are a lot of processed ‘agricultural’ foods in the form of protein bars and treats that are sweetened with artificial sweeteners. As long as they don’t excessively raise blood sugar and insulin levels, they are not a threat to ketosis.

Let’s come to the differences.

Dairy is not part of the paleo diet but can be part of a ketogenic diet. While milk contains quite a lot of milk sugar (lactose) and should be restricted, most full-fat dairy is safe for ketosis when consumed in moderation. However, many people following keto limit dairy or avoid it altogether. This is an example of how the two diets differ by their definition but resemble each other in practice.

Fruits are eaten on a paleo diet, but very limited on a keto diet, because they usually contain too much sugar in the amounts people consume them in. Low-sugar fruit such as berries can typically be eaten in small amounts.

Another difference is the use of sweeteners. Basically, anything that does not kick you out of ketosis can be used on the keto diet. This includes artificial sweeteners, such as aspartame, the sugar alcohol erythritol and some natural sweeteners such as monk fruit and stevia.

Check out our article on keto sweeteners to learn more.

Strictly speaking paleo diets don’t allow sweeteners. In practice though, paleo dieters will often use them. Some though mistakenly lean towards ‘natural’ sweeteners like honey, maple, and agave syrup which all contain a lot of sugar. Stevia is the only natural sweetener that, depending on the interpretation, can be compatible with keto and paleo diets.

Because the keto and paleo diets agree on many things they can be easily fused to a keto paleo diet – you get the best from both worlds. A keto paleo diet excludes milk products, fruits, and sweeteners (stevia is optional) and includes veggies (non-starchy, leafy-greens preferred), all kinds of meat, fish, eggs, and nuts.

Is this food keto?

Get the keto score, insulin index & nutrient density for 4000+ foods

What’s better: keto or paleo?

It’s hard to say which of the two diets is “better” as they aren’t really even based on the same set of ideas. In one sense, the paleo diet is typically ketogenic, and the modern ketogenic diet is popularized via lot of foods ‘paleo’ foods like steak and avocado.

What you eat needs a bit more nuance than just what it does to your ketone levels or if it’s something your ancestors may have eaten. Both are useful ideas to consider, none are sufficient on their own to figure out what you should eat.

Furthermore, it also depends on your preferences, personal goals, and medical history. For sure though, both diets are far superior over the traditional western diet.

For certain health conditions the evidence is starting to come in.

#1 For weight loss

Most people can lose a lot of excess body fat, simply by cutting out grains and processed foods. So both diets are great for fat loss[5][6]. There are no side-by-side studies comparing the two diets so far. But in general, the lower the carb content, the easier the fat loss. Paleo can be seen as a low carb diet, but carbs are lower on a keto diet.

Low carb diets keep blood sugar and insulin levels relatively stable, and usually help keep ravenous hunger pangs at bay. Ketogenic diets have an additional advantage: Ketones are known to suppress appetite, which is probably one of the secrets behind the diet’s success for fat loss[7][8].

Bottom line: Keto and paleo diets are good for weight loss, but the lower the carbs the better.

#2 For diabetes

For diabetes, the situation is similar. Refined carbs and sugar cause chronically high insulin levels, which in turn leads to insulin resistance, the characteristic feature of type 2 diabetes[9][10]. For this reason, low carb diets are a very powerful treatment to reverse type 2 diabetes[11][12]. The lower the carb content, the better the blood sugar control and the sooner pathological insulin resistance disappears.

bottom line: Paleo diets are a great start, but due to their lower carb content, a keto diet is better.

#3 For PCOS

Polycystic ovary syndrome (PCOS) in an endocrine disorder and the most common cause of infertility in women. Women with PCOS tend to have high insulin levels and are at an increased risk of insulin resistance. Chronically elevated insulin levels are thought to cause the hormonal imbalance that is seen in PCOS[13]. These women have too high levels of luteinizing hormone (LH) and too little follicle stimulating hormone, which leads to increased production of male hormones, such as testosterone.

If you already have a disposition for insulin resistance, you don’t want to make things worse by following a diet that causes insulin resistance.

There are not many studies looking at keto or paleo diet for PCOS. However, in one pilot study with 11 women, the ketogenic diet could significantly reduce weight, lower free testosterone, and lower the LH/FSH ratio and fasting insulin[14].

Bottom line: Because the keto diet is lower in carbs than the paleo diet, it might work better for PCOS. Compared to a standard western diet, both diets dramatically lower insulin levels and improve insulin sensitivity.

#4 For inflammation

Chronic inflammation is associated with an increased risk for many modern diseases, such as heart disease, cancer, obesity, diabetes, and allergies[15][16][17]. While acute inflammation is the answer of the immune system to a harmful invader, you want to keep the background inflammation as low as possible.

High sugar intake is known to cause inflammation, and low carb diets are known to reduce inflammation[18]. Again, it looks like the lower the carbs, the better.

The ketogenic diet has, however, an additional advantage because ketones itself also have anti-inflammatory effects[19].

Another way to reduce inflammation is by optimizing the omega-6 to omega-3 fatty acid ratio. Too much omega-6 is a driver of inflammation, whereas omega-3 has anti-inflammatory effects[20][21]. Seed oils contain vast amounts of omega-6 fatty acids, and you should avoid them by all means. Luckily, both the keto and paleo diet do not contain seed oils. By ensuring an adequate omega-3 intake, you can also shift the omega-6/omega-3 ratio to your advantage.

Fatty fish and meat ruminant animals like cows are a centerpiece foods for keto and paleo diets, both of which enable you to have good omega-3 fatty to omega-6 fatty acids ratio.

Bottom line: Compared to the standard western diet, keto and paleo diets are both anti-inflammatory, but the keto diet might be more powerful.

#5 For autoimmune diseases

In an autoimmune disease, the immune cells are not able to correctly distinguish self from non-self and start to attack the body’s tissues. Autoimmune diseases are also characterized by an overactive immune system and high levels of chronic inflammation. Ultimately, a diet that reduces inflammation is likely beneficial for people suffering from an autoimmune disease.

The autoimmune protocol (AIP) is a rigorous elimination diet. It’s based on the idea that lectins, oxalates and other plant defense compounds are high in modern versions of a paleo diet and have the potential to to cause people small and large health issues[22][23], AIP was popularized by Robb Wolf that and may be better suited to lowering the overall burden of chronic inflammation and immune reactivity from plants.

It eliminates anything that might potentially trigger the immune system. Because it is based on a paleo approach, it does not include grains, industrial sugar, seed oils or any kind of processed foods. Beyond that, it also excludes nuts and seeds, and nightshades (eggplants, peppers, tomatoes, and potatoes).

A carnivore diet takes the elimination a step further and is arguably much simpler to implement.

Scientific evidence regarding the efficacy of the AIP protocol is limited, but a small study assessed the effect of the diet on irritable bowel syndrome (IBS). Patients presented two different forms of IBS, Crohn’s disease and ulcerative colitis. At least the latter is known to be an autoimmune disorder where the immune system attacks the lining of the gut. In these patients, the AIP protocol relieved symptoms and lowered inflammation[24].

Despite lacking scientific evidence, there is plenty of anecdotal confirmation that the AIP diet might be beneficial for treating autoimmune disorders. Many people who tried the diet, noted an improvement of symptoms. The problem with anecdotal stories is that you only hear success stories because failures tend to be reported less.

What about keto? As discussed in the previous section, a ketogenic diet reduces inflammation. Because autoimmune diseases are characterized by high levels of inflammation, a reduction can only be beneficial. In multiple sclerosis (MS), the immune system destroys the protective myelin sheath that surrounds neurons. There is growing evidence that the ketogenic diet can improve the condition[25].

It’s hard to tell which of the two diets is better for autoimmune conditions. The AIP protocol while at the same time restricting sugar intake (fruits and honey) might be a good bet.

bottom line: a carnivore diet seems to be the best of both worlds in terms of getting the inflammation-modulating effects of ketosis and the elimination aspect necessary to treat many autoimmune conditions.

Does paleo or keto have side effects?

When going on a low carb diet, many people experience carb withdrawal syndromes, known as the low carb or keto-flu. Learn more here on how to cure the keto-flu.

Apart from these initial symptoms, neither paleo or keto have side effects. It is said that they may cause kidney problems because of their supposedly dangerously high level of protein intake. This is nonsense.

It has never been shown that high protein intake causes kidney disease in healthy people. Furthermore, the keto and paleo diets are not ‘high’ in protein in the sense that our body’s can’t handle it, they’re higher in protein than the typical western diet that is deficient in protein.

Keto meal examples

Paleo meal examples

So, which is better?

Both keto and paleo diets have huge advantages over the traditional western diets. You cannot say which of the two diets is better as they’re defined by the aspect of diet they’re focused on.

Your diet should be based on your goals and general health principles; nutritional ketosis and eating evolutionary appropriate foods are very important concepts embodied by keto and paleo diets, respectively.

Keto may be superior for health conditions, such as diabetes and PCOS and is more powerful when trying to reverse obesity. Nutrita is here to guide you take the best from each and keep the big picture in mind.

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Written by Raphael Sirtoli, MSc, Ph.D. (candidate)

Raphael Sirtoli has an MSc in Molecular Biology and is a Ph.D. candidate in Neuroscience at the Behavioral n’ Molecular Lab in Portugal. His understanding of metabolism, nutrition and clinical medicine is the base upon which Nutrita’s knowledge derives from. He loves open scientific debate, Crossfit, football, hiking, and cold water immersion.