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All About… Sugar


Sugar is such a hot topic at the moment that it has, as all hot topics do, created polarisation within communities of healthcare practitioners. By a cursory glance at the latest nutritional bestsellers you would be forgiven for thinking that Sugar is the devil incarnate, capable of mass inflammation, toxic poisoning, addiction and solely responsible for our obesity and diabetes epidemics.

Look at the bloggers and Instagrammers and you get a different slant. The “If It Fits Your Macros (IIFYM)” exercisers are piling up mounds of junk food and hash-tagging it with every #fitspo phrase they can come up with – claiming that within a balanced macronutrient split and a life of working out you can (quite literally) have your refined-sugar cake (topped with drizzles, candies, sprinkles and frostings) and eat it too…

And so where do we here at Paleo in the UK stand? Is there a “Truth about Sugar” (as many click-bait articles would have you believe)? And why is it such a polarising foodstuff? Lastly – where does Sugar fit on the Paleo and Autoimmune Paleo landscape? All these topics will be covered in the below article.


But first:


The Hunter-Gatherer Diet Debate


Perhaps it seems blindingly obvious to you that Palaeolithic Man (or hunter-gatherers, ancient tribes etc.) did not consume Sugar. And you’d be correct – they absolutely did not. At least not in the form we see it today – whether that’s in packets of white crystallised powders or made into any number of brightly coloured confectionary treats.

And yet it must be acknowledged that ancient hunter-gatherers, in a way that is strikingly similar to modern humans, were seeking Sugar, almost constantly. They wouldn’t have known that that was what they were doing – but in a world where nutritional availability was a challenge it was actually NUTRIENT density that was prized… it was CALORIC density.


Here is where the word “Paleo” falls down, in our eyes – because whilst the content of a Modern Paleo diet might resemble that of a hunter-gatherer tribe, the motivation for eating this way is undoubtedly different between the two eras.


In hunter-gatherer tribes, food choices were ones of availability and opportunity – they were constantly seeking easy ways to fulfil the required intake.


In Modern society we are purposely limiting our food choices to avoid the diverse array of food opportunities – we are trying to prevent consuming far more than our required intake.



This is why Sugar is such a ‘dangerous’ substance in some people’s eyes. As we have said in many places on this site, our biology is inherited from our ancestors – and we have not evolved anywhere near equally to the nutritional availability which surrounds us.

Our ancestors were Sugar-seekers. Or, more accurately, they craved the ‘easy foods’ which were ‘high reward’ for ‘minimal effort’. This was a perfect biological trait in an environment where food was scarce and every morsel was acquired using effortful processes of either lengthy hunts or active harvesting.

In the modern environment, food acquisition is a case of popping into the supermarket and food availability – Sugar availability – is cheap, easy and too convenient.

All of which means that whilst ‘sweetness’ was the prized goal of a hunter-gatherer, in a Modern Paleo diet it can’t be the drive and the focus. This is why Sugar, the refined kind that would NOT have been found in the wilderness, is not included on a Paleo diet. That doesn’t mean all sweet things are off the table, however. But the biochemical properties of “sweetness” really do mean that in a diet founded on a principle of low-inflammation and nutrient-density, that sweet fix must come in a less damaging package than Sugar itself.

But where, really, does the ‘damage’ come from with refined and processed Sugars?


The Biochemistry of Sugar


Perhaps the most popular phrase about Sugar used recently has been that it is “toxic”, second only to the notion that it is “addictive”. Using these words is undoubtedly sensational – but do they have any basis in the reality of the biological impact of Sugar on the human body?


Addictive: the notion that sugar is addictive comes from dovetailing our understanding of the impact of Sugar on the brain and our understanding of the biochemistry and neurology of addiction itself. We believe that addictive behaviours or substance addictions actually arise out of a similar biochemical place: the activation of the dopamine pathways in the brain and the activity of a particular brain region known as the nucleus accumbens. Dopaminergic inputs are released into the nucleus accumbens after experiencing ‘reward’.

It is important to distinguish ‘reward’ as opposed to just referring to this as ‘pleasure’ because the notion of ‘reward’ indicates that there is a drive towards the behaviour – basically we seek out the experiences which can reward us and this reinforces the behaviour and/or consumption.

Anything that stimulates the dopaminergic activity into the nucleus accumbens is experienced by humans as deeply satisfying and ‘rewarding’. We therefore desire to repeat that experience. This is networked in all sorts of behaviours – from seeking food and drink to maternal nursing and even to the biochemistry of exercise. Having this region deep within our limbic system is theorised to be a key reason for our survival as a species. Prioritising ‘rewarding’ behaviours and substances meant that we sought food, water, enjoyed sweet (i.e. more calorically dense) foods most, desired to be maternal and nurse our offspring, and even felt the thrill of the chase when hunting our prey to eat.

Sugar is a substance which directly lights up the nucleus accumbens in a way that is similar to other stimulating and rewarding activities. Euphoriant drugs such as opioids and amphetamines do the same thing. Sort of. This is why Sugar has been deemed addictive – because it can light up the reward centres in our brain in a similar way to narcotics which are known to be addictive substances.

The reality is that drugs formulated to bind to opioid receptors in the brain and influence neurotransmitter activity (both release and reuptake) are very different from sugar, which is basically a chemical compound which can elicit a similar firing of neuronal networks though does not interfere with brain chemistry in quite the same way. Sugar can be addictive, but only in the way that any reward-seeking behaviour can be. Those who are addicted to exercise, gambling, sex, shopping etc. are all experiencing a very similar neuronal prioritisation which is driving behaviour. The addiction is actually to the dopamine release – the focus of the addiction can differ.

This is why addictions are not universal. Not everyone who gambles becomes addicted, nor does everyone who consumes drugs – or even Sugar. Sugar certainly can become problematic in that it drives behaviour, but that doesn’t actually mean that it should be banned for everyone. Quite whether you become driven to seek out sugar has far more to do with individual biology than an innate feature of Sugar itself.



Toxic: this word is a little less founded in biochemistry and a lot more founded in being overly dramatic. Sugar isn’t any more toxic than perfectly benign substances like water. And yet it does have some fairly unique abilities to drive two things: inflammation and metabolic dysregulation.

So how is sugar inflammatory and why is it eliminated on Paleo?

Human bodies are like chemical factories: we are doing biochemical conversions literally all of the time. Even as you read this certain molecules are being bolted on to others, fragments of compounds are being popped off and exchanged for others, substances are being made into different substance and, throughout all of this activity there is a constant exchange of energy. This all happens because we are trying to have energy in our cells to sustain life, scientifically termed ‘cellular respiration’.

All of these energy exchanges within the machinery of cellular respiration release byproducts. These byproducts are not always benign.

To save us a deep dive into the biology of oxidants and antioxidants, for now it is enough to know that simply by breathing and being alive you are continually producing products known as Reactive Oxygen Species, or ROS. ROS are oxidants and are basically toxins. As such they create inflammation – and they are not designed to stay within the human body. The load of ROS creates something called “oxidative stress”, of which you might have heard. Though this is a bit of an oversimplification, oxidative stress is the stress that comes about through the biochemical process of being alive.


The way we balance ROS in the human body is through our antioxidant levels. The secret to the Paleo mantra of nutrient density comes about because you can derive a high quantity of antioxidants (which help balance ROS) from nutrient-dense foods such as green-leafy vegetables and polyphenol rich, deeply coloured fruits.


One of the normal life processes that creates an upswing in the production of ROS is eating. Eating anything at all raises the activity of the cell in order to process/absorb/derive energy from/store the incoming foodstuff and this acceleration of activity also increases ROS.

Everything you eat needs to be in one of two forms before it is taken into the cell for ‘cellular respiration’ (i.e. it becomes useable energy). One of these forms involves fats and is not going to be discussed here. The second of these forms is glucose (and/or fructose, which work similarly)… Everything that you eat is changed biochemically until it is glucose and it can then be processed by the cells’ energy production cycles.

Which is what brings us back to Sugar. With many foods there are steps involved in getting from the food itself to the glucose molecule required for our cells. When consuming highly refined, processed Sugar you are eating a molecule of glucose and fructose bound together. This puts simple glucose almost immediately into the bloodstream. Our bodies are incredibly closely regulated – and our bloodstream is perhaps the most tightly regulated of all. The concentration of glucose in the blood is regulated by hormones such as insulin and glucagon – and there is only approximately a teaspoonful of sugar that is supposed to be in your entire bloodstream at any given moment in time. Any more – as happens when you eat a sugary food – and your body will release insulin to shuttle glucose out of the bloodstream and into the cells.

Once there, cellular respiration can commence at an incredible rate because of the high quantity of glucose made available. High levels of cellular respiration equals high levels of Reactive Oxygen Species and high levels of oxidative stress…

Ergo… Sugar causes inflammation.

Wow, OK – so Sugar, simply because it is so easily utilised by the body, can create an upsurge in the level of oxidation our bodies experience and therefore can create more stress on the body than the ‘reward’ it gives. This would classify it as ‘more anti-nutrients than nutrients’, and yet Sugar really isn’t a nutrient at all… it is a source of nutrient-free calories and energy. That doesn’t make it useless, because sometimes this quick burst of energy is exactly what you need… But when there are other foods available, Sugar is never going to rank highly as an ideal source of energy.


Sugar, Weight Gain, Obesity – Blood Sugar


The most damning of verdicts on Sugar in recent years has arisen because of its link to raising Insulin levels in the blood. A full explanation of the Insulin-Obesity hypothesis has taken esteemed authors hundreds of pages to write, so we are not going to go into great depths here.

However, there is a consensus that Sugar can contribute to weight gain and increased adiposity. The arguments arise because different professionals will disagree on the mechanism of this – whether consuming Sugar simply provides a caloric surplus and/or whether the role of Insulin in storing cellular energy is linked to an increased in storing excess calories from the diet as fat.

Excess Sugar consumption is also tied to obesity and diabetes because it has been shown to lead to Insulin Resistance – a condition in which Sugar consumption is regularly high so levels of Insulin have to be maintained at a high level (to pull that blood sugar level down to the teaspoon amount). Regularly high levels of any hormone, of which Insulin is one, will eventually create a ‘resistance’ to it, in which the receptor sites designed to register the presence of Insulin in the blood  slowly become ‘deaf’ to it. This deafness leads to high circulating sugar levels – an upswing in the inflammation explained above, and eventually fat accumulation as the sugar needs somewhere to go and thus gets stored in fat cells instead of being used for energy.

Intriguingly, the state of Insulin Resistance is a state of a simultaneous caloric surplus whilst experiencing cellular starvation. Insulin is the hormone which signals presence of energy for the cells to receive. If the cells are deaf to the presence of Insulin in the bloodstream, they do not open up to receive the energy. They are effectively starving despite there being plenty of available energy within the body.

That is an incredibly simplistic view of metabolism, Insulin and the obesity/diabetes debate…

Unfortunately when people only read short treatments of this science it gives the impression that any Sugar at all – even Sugar that comes from carbohydrates such as potatoes and starchy vegetables – might have this same Insulin impact within the body. This is where the basic biochemistry can be manipulated into statements such as ‘carbohydrates are evil’ and ‘carbs cause diabetes’.

The truth is both more complex, and yet more simple. The entire body is built on balance. Insulin is an essential hormone which is designed to rise and fall depending on the carbohydrate and Sugar load of a meal. This is entirely appropriate and does not lead to resistance or diabetes. In a state of energetic surplus, caloric excess and over-feeding, the biochemistry can become slightly deranged. If this happens on the odd occasion even that is not too terrible for the human body.

It is the daily, repeated high levels of all of the chemicals and hormones that, over the long term, can dysregulate metabolism and metabolic health. All of which means that, yet again, Sugar itself is not the nutritional bogeyman. Instead, as with absolutely everything, when consuming in excess and without a balanced approach, Sugar can become metabolically damaging.

The one issue with Sugar, however, is that this starvation/hunger/satiation mechanism is that it can actually drive behaviour in a way that is entirely separate to the dopamine/neurotransmitter story above.

As glucose in the bloodstream is brought down by Insulin, the uptake of glucose can keep going beyond the point of neutral (that teaspoon amount) and to the stage where there is too little circulating glucose in the blood. This whole process can happen relatively quickly if the source of the glucose was refined Sugar – all of which means that the body senses an energetic lack with no sight of more calories and suddenly experiences a reactive hypoglycaemia… The natural next step is a message of emergency to the brain demanding that we eat more food.

At this point we are actually beyond calories satisfying hunger and true energetic needs of the body. We have instead stepped onto the rollercoaster of balancing blood sugars – constantly needing to prop up our bodies with more fuel because we are not finding a homeostatic balance in which our bodies feel satiated and well nourished.


Sugar On Paleo


When looked at in all of the above consequences it seems obvious that Sugar is one of those foods which can carry dramatic adverse consequences for human biology. Much like many other substances and foodstuffs, it does this in situations where it is consumed in excess and/or without balance and control.

The confounding factor with Sugar is that because of the mechanisms of action – both in terms of neurotransmitters and brain function AND in terms of metabolism – CONTROLLING or REGULATING Sugar consumption can be an almost impossible task.

These biological mechanisms which make regulating Sugar consumption difficult were set up in the era of the hunter-gatherer. It is our biological heritage that can drive our modern overconsumption.

And the food environment when it comes to Sugar has evolved far more rapidly than our bodies. The sweetness prioritised by hunter-gatherers was fruit, berries, perhaps the whole sugar cane if they were geographically located somewhere where this was accessible. Honey would also have been a prized possession when it was found.

Fruit and honey are actually not just Sugar, either. Whilst their dominant properties may be calories and sweetness, they are also rich in nutrients. It is for this reason that “Sugar” is not completely eliminated on any Paleo diet. Instead, we recommend balanced consumption of the whole, natural, unrefined sources of sweetness: fruits (whole, not juiced), honey (raw, unfiltered) – and blackstrap molasses (basically the ‘stuff’ left over from sugar cane once they’ve extracted the white powders). This isn’t about being purist or ideological about ‘clean’ or ‘natural’ food – instead, it is recognising that Sugar is always going to be something that humans find difficult to control their consumption of because of the mechanisms highlighted above.

When consumed in the whole food forms mentioned here Sugars are actually much more nourishing because they are accompanied by other chemicals, compounds and health-giving properties. The happy byproduct of whole food sources of Sugar is that they are far more difficult to over-consume. Make no mistake – honey will have the same impact in the body as any other fructose/glucose combination (like table Sugar). It will, however, be much more flavourful and actually satiating – which is what makes honey or fruit sugars (again, in their whole forms and not in processed ‘date syrup’ or ‘agave nectar’ forms) a Paleo option.


Sugar on AIP


Inflammation is the enemy of the autoimmune patient… which means that Sugars are a much more complex issue. Tolerance of Sugar will be very individual and dependent upon the autoimmune condition which you are facing and the comorbidities that you face. Fatigue, brain fog, weight gain and cortisol dysregulation will NOT be helped by using Sugar as a calorie source – and states of swinging blood sugars are always going to contribute to stress states within the body and risk exacerbating any autoimmune state of heightened immune reactivity.

Again, moderation is your friend and individual responses must be monitored…


The Pull Of Sugar


Lastly, we want to make mention of something that is vital to us here at Paleo in the UK…

Food is about much more than just food. It is more than the biochemistry – it is more than the brain chemistry.

Food is emotional, social and sometimes even spiritual. Food has many contexts and feelings attached to it – it can carry cultural, familial or simply personal significance.

Sugar is one of those foods that carries a lot of ‘guilt’ because it can be easily binged upon, it can be difficult to control our behaviour around – and it can make us feel different things. Any food that has the power to change our emotional state automatically feels frightening and disempowering.

This is why Sugar has become such a complex phenomenon in our modern nutritional world. We feel controlled by Sugar and in many cases that leads to an attempt to exert control over it. This denial of the hedonistic pleasure of certain foods is absolutely not what any Paleo or AIP approach is about. The fact that food can be social, emotional and cultural is a big part of tribal connection and the socialisation which is necessary for any truly healthy life.

For this reason we will return to the topic of moralistic food choices often on our blog. Sugar is not the stuff of the devil, nor is it a nutrient-dense superfood. It is complex, and our emotions around it are even more so. But Paleo is not about punishment, it is about nourishment. Consuming natural Sugars is one of the simplest and most ancient of human pleasures. As such, consuming such sources of Sugar definitely forms part of living a wholesome, healthy life.


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Functional Medicine Consultant, Health Coach & Genetics Specialist - working holistically to treat chronic health conditions including mental health issues, complex digestive disorders, hormonal dysregulation & autoimmunity.

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Paleo in the UK is the first Paleo and AIP dedicated resource based on both research and clinical applications, run by a UK-based Functional Medicine Consultant & Health Coach

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