What is the Paleo Diet?

What is the Paleo Diet?


Of the fourteen definitions, there are some similarities, so it seems that the Paleo Diet comes from the word Paleolithic. Meaning it is inspired by the consumption of wild foods and animals. 

Paleolithic nutrition is based on the principles of evolutionary biology with a focus on the low or moderate carbohydrate options available to hunter-gatherers. The largest argument against the Paleo Diet is that it’s hard to imagine one basic diet covering the entire period from 2.6 million to 10,000 years ago, with people living in a wide range of climates and geographic regions.

The Paleo diet consists mainly of grass-fed and pasture-raised meats, vegetables, fruits, fungi, roots, and nuts. It excludes grains, legumes, and dairy products, along with limiting refined sugars, starches, processed foods, and oils.

Overall, the Paleo diet should boast a high protein intake, moderate fat intake and low-moderate carbohydrate content.  

Let’s take a look at these macronutrients in a little more detail.


Proteins are large, complex molecules composed of hundreds to thousands of amino acids.  They are literally the building blocks of the body. Protein is required in the diet to provide a source of amino acids to build, repair and replace body proteins.  

Proteins in the body have numerous functions.

  • Major structural components of hair, skin, nails, tendons, ligaments, and cartilage, 
  • Hormones are composed of protein molecules – these include insulin and glucagon which are key to maintaining blood sugar levels,
  • Proteins are found in the blood – for example, haemoglobin carries oxygen between the lungs and cells, lipoproteins carry fats throughout the body and transferrin carries iron through the blood.  
  • Proteins are also found in the immune system in the form of immunoglobulins to make the antibodies that provide resistance to disease.  

All proteins are in a constant state of renewal and degradation, so we need a consistent supply.  


Fat enters the body from the diet and finds its way through the stomach, and into the small intestine. Here it is bombarded with enzymes from the pancreas (lipase), and bile salts from the liver. 

The fatty acids are now small enough to be passed through the lymphatic system and then into the bloodstream. 

Fatty acids are used throughout the body for a range of functions, primarily energy, but if they are not needed, they can be stored in adipose tissue.  Here, they are an energy source for a later stage.  They also serve as insulation, protecting the body from heat loss and from injury or trauma to vital organs. This is where the idea came from that fat makes you fat.  It is true, fat can be stored as fat, but this is when intake exceeds requirements; the same applies to excess intake of carbohydrates (they too can be converted to fat to be stored).

Fats are also crucial to eye health, brain health, and hormone production. Fat intake will aid in the production of cholesterol. Cholesterol (HDL) is the precursor to our sex hormones, testosterone, oestrogen, and progesterone. If we are not receiving adequate fat, and cholesterol (HDL) intake is low, we may experience hormonal imbalances which have wide-ranging impacts on our health. 

The key is to eat the right kind of fats which include unsaturated fats like oily fish, nuts, seeds, olive oil, and avocados. 


Carbohydrates are made up of three components. Fibre, starch, and sugar. Sugar is a simple carb, having fewer molecules to digest and break down, it sends an immediate burst of glucose into the blood stream. This is what we can use as energy.  

Fibre and starch however are complex carbs, having longer chains of molecules. Starch takes longer to digest, having a more gradual effect on the body. Fibre, on the other hand, is a non-digestible complex carbohydrate. Although it’s not digestible, it can be fermented in the gut, and this is where we reap many of its rewards. 

When fibre is fermented in the gut, it produces compounds known as short-chain fatty acids or SCFAs. These guys can provide fuel for intestinal cells, strengthen the gut barrier, and keep those tight junctions nice and, well, tight.  SCFAs also stimulate mucous production, which actually forms another barrier in the gut. All of these roles play an important part in protecting against harmful pathogens.  

But the other benefit of these compounds is the impact on our mental well-being. 

Short-chain fatty acids

SCFA’s can affect our mood.  They affect levels of neurotransmitters (which are the chemical messengers in the body’s nervous system) that can alter how we feel and behave.  Higher levels of butyrate, which is one of the many SCFA’s, have been seen to improve mood and reduce anxiety scores. (i) 

But it’s not only SCFA’s that can influence our mood.  Certain bacteria that are found in our gut produce certain neurotransmitters too.  For example, lactobacillus bacteria produce the neurotransmitter GABA which is seen as the brakes of our nervous system.  Overall, this chemical messenger contributes to feelings of calm.

This is the concern in many low-carbohydrate diets – if we remove carbohydrates, do we also remove fibre which is of great benefit to our health?  

Again, the note to make is the type of carbohydrate.  Simple carbohydrates are those that can send our blood sugar balance a little off track, whereas complex carbohydrates serve a range of benefits in our bodies. 

Is the Paleo Diet Good for Me?


Many suggest that the Paleo Diet is great for weight loss, and in randomised control trials, weight loss has occurred.  But what is interesting is that two years later, weight had been regained. (i)

Others have suggested that the Paleo Diet improves glucose tolerance and insulin sensitivity.  However, systemic reviews have concluded that the Paleo Diet did not differ from other types of diets commonly perceived as healthy with regards to effects on glucose and insulin balance.  

Others have suggested that the Paleo Diet improves glucose tolerance and insulin sensitivity.  However, systemic reviews have concluded that the Paleo Diet did not differ from other types of diets commonly perceived as healthy with regards to effects on glucose and insulin balance. (i)

Further research highlights that, of the health benefits associated with the Paleo Diet, there are generally short-term improvements, as opposed to long term.  This is likely because eating patterns regress. (i)

So is there any point in the Paleo Diet?


Despite there being inconclusive data, there are several principles in the Paleo Diet that can be incorporated into day-to-day living to create sustainable health benefits.  

Reduced intake of ultra-processed foods

By the very definition of low-carbohydrate diets, those choosing this approach will naturally reduce their intake of ultra-processed foods. 

Ultra-processed foods are made mostly from substances extracted from foods, such as fats, starches, added sugars, and hydrogenated fats.  Examples of these foods are frozen meals, soft drinks, hot dogs, fast food, packaged cookies, cakes, and salty snacks. 

The high intake of these foods has been associated with obesity, cardio-metabolic risks; cancer, type-2 diabetes, cardiovascular diseases, irritable bowel syndrome, depression, and ultimately all-cause mortality. (i)

Sustainable Eating 

The Paleo Diet emphasizes local, sustainable, organic, and non-GMO foods along with grass-fed meat options. Where we source our food from is vital.  If it isn’t grown or raised in nutrient rich environments, how can we expect to gain nutrition from it?  

Grass-fed meats consistently score better on nutrient content than corn-fed for example, and they include far higher quantities of the beneficial omega-3 fats than factory-farmed.  You’ll also find higher antioxidants in grass-fed animals. (i)

The importance of avoiding pesticide laden food is particularly important – we know that pesticides overburden our detoxification systems, in addition they significantly affect our gut health by skewing the microbial community found within in.

Are there any nutrient deficiencies associated with the Paleo Diet?

This diet restricts the consumption of eggs, dairy, and gluten-containing grains, which may increase the risk of micronutrient deficiencies.

It has been found that those following a strict Paleo Diet are at risk of Vitamin D, calcium, and choline deficiency.  

Supplementation is often practiced, but many individuals tested then exceed upper limits for certain micronutrients.  (i)

The Bottom Line?

There are some great principles that the Paleo Diet is based on, for example increased fruit and vegetable intake and reduced intake of ultra-processed foods, but the long-term data doesn’t yet find a consensus.  

There may be short-term weight loss, or improvements in fatigue, but could this be due the foods that are being removed from the diet, like ultra-processed foods?

It’s important to opt for a diet that is sustainable.  Our top tips are to reduce ultra-processed foods as much as possible, eat plenty of fruit and vegetables and source the most nutrient rich foods that your budget will allow.  

If you are considering following any strict dietary protocols, seek the advice of a qualified practitioner for support.