11 Harmful Effects Of Sugar

17 min read

It just hit me that in all my three years of blogging on this site, I’ve not quite addressed the topic of sugar. I have written about where I feel fructose should sit in the ancestral cuisine, but that only included an evolutionary tale of fructose fattening us up to survive the harsh winters of the palaeolithic wilderness.

So this article is a chance to nail down the unsavoury side of a macronutrient that’s constantly up against seed oils in a tug of war to decide who gets to be called the architect of chronic disease.

What Is Sugar?

glucose vs fructose

It’s worth starting with a primer, even at the risk of being painfully obvious, because there are still plenty of people who think sugar has to be sweet.

Sugar is a mix of glucose and fructose, and while the latter can be the more problematic of the two, glucose doesn’t get to skip the blame. In the absence of fructose, glucose can still be converted to fructose via the polyol pathway.

Fruits are typically half fructose and half glucose. Table sugar is also half glucose and half fructose. It’s the fructose that produces sweetness. Starches are made of glucose without the fructose, and generally lack sweetness. But they still are very much carbohydrates that break down into glucose, that can potentially turn into fructose.

So you can’t say you’re cutting down on sugar, and then continue to pile the plate with pasta. Because that pasta is still going to end up as sugar, and it’s still going to wreak much of the same havoc that a pile of table sugar will.

The Origins Of Sugar

honey ancestral diet

This day and age, sugar is pervasive across the food supply, but it wasn’t always this dominant. Some people will point out the presence of sugar in the ancestral diet, in the form of fruit and honey. But that needs to be taken with an asterisk.

Fruit, for instance, was only available for brief periods in the year, and would have been far more fibrous and lacking in sugar when compared to its modern supermarket-ready counterparts.

Honey is a beloved part of the diet of the Hadza, a tribe of modern-day hunter gatherers. But, as I’ve already tackled in my previous article, their current environment is a pale shadow of their palaeolithic predecessors. There would have been far more elephants, which not only would have been a preferred food source (because they provide actual nutrition), but would have also spent their leisure time demolishing the trees that beehives normally occupy.

So it would be a reach to say that fruit and honey were palaeolithic staples.

With the end of the palaeolithic came the first agricultural revolution in 10,000 BC, which ushered in the age of starches. All the ‘civilisations’ of ancient history emerged as grain states, making up for their protein deficiencies and diminished stature with an abundance of calories that enabled population growth to spike.

Now the disclaimer is out of the way, let’s read out the crimes of the world’s favourite drug.

1. The Toxicity Of High Blood Sugar

high blood sugar effects

Do you know how much glucose the body has in the blood? Just 4 measly grams. It’s a teaspoon’s worth.

Now think how easy it would be to overload that capacity when you reach for a glazed doughnut that packs a hefty 50 grams of sugar.

The body will do its best to limit the damage of that sugar bomb by marshalling the glucose into the muscle sink, where it can be stored as glycogen.

But then you have the confounder that arises when those muscle cells are non-responsive to the effects of the key storage hormone, insulin. This is known as insulin resistance, and it unfortunately describes a huge chunk of the population at this point, with 13.6 million people in the UK being prediabetic, and 4.9 million with diabetes.

Not that you only need to worry if you’re blessed with insulin resistance. It’s just the severity of high blood sugar that changes.

The most obvious consequence of high blood sugar is the state of inflammation and oxidative stress that it plunges the body into. Glucose can stick to proteins in the bloodstream to form toxic advanced glycation end products (AGEs), which permanently impair the affected tissues, and fan the flames of inflammation, oxidation, and immune reactions.

And if you’ve been stacking your cells with brittle polyunsaturated fats, otherwise known as dry tinder, those AGEs get to combine with them for a spectacular cascade of free radical damage.

The cellular damage caused by oxidation and glycation impairs insulin signalling, which when combined with the high levels of insulin and glucose that accompany high blood sugar, can lead to pathological insulin resistance.

Alongside diabetes, high blood sugar is also tightly linked with blindness, infertility, and heart disease.

Symptoms of hyperglycaemia

  • Feeling very thirsty
  • Peeing a lot
  • Feeling weak or tired
  • Blurred vision
  • Losing weight
  • Skin discoloration

Fructose increases glycation tenfold when compared to glucose, in what will set the trend for the rest of this article.

2. The Turbulence Of The Sugar Rollercoaster

sugar rollercoaster

The problems don’t stop with the initial toxic spike of glucose in the bloodstream. Things continue to get worse, as the body ramps up insulin production in its struggle to clear the excess glucose. It often does too good of a job, and the sugar eventually craters into a state of hypoglycaemia. Otherwise known as low blood sugar, the inevitable next stop on the rollercoaster.

Hypoglycaemia is a different sort of emergency, it’s energy scarcity. 

Symptoms of hypoglycaemia

  • Anxiety
  • Palpitations
  • Diaphoresis
  • Tingles
  • Hunger
  • Lack of concentration
  • Headache
  • Dizziness
  • Confusion
  • Speech disturbance

The body responds by pumping out stress hormones to break things down and hunger hormones to force you to go out and find something to bring glucose back to normal levels.

This is a trap. The rampant appetite will egg you on to find the most calorie dense foods, and in the mayhem, you’re likely going to overindulge, once again flooding the body with more sugar than it can handle.

Putting you back in the same pickle you were in a couple of hours ago. Constantly see-sawing between periods of hyperglycaemia and hypoglycaemia will present itself in wild swings of energy, emotional turbulence, poor sleep quality, and insatiable cravings.

3. Dopamine Depletion

dopamine deficiency

The question whether sugar is a drug or not is a hot-button topic that deserves its own article, but what isn’t under question is its ability to spike dopamine. That in and of itself is going to pave the way for habitual behaviour that consistently depletes motivation levels and erodes wellbeing.

Dopamine is the molecule of more, the neurotransmitter that gets you to strive in the pursuit of rewards. The problem with dopamine, is that it can easily become hijacked and become deeply detrimental if there is no effort preceding that reward.

When dopamine comes easy, you become resistant to that dopamine, which means you need more dopamine to get the same hit, and all that comes at the expense of draining the central dopamine reservoir that dictates your general motivation levels and wellbeing.

In other words, being a sucker for the sugar drip has the risk of turning you into a miserable vegetable with no capacity for extended effort. You won’t just be weak for sugar, you’ll also struggle to get up at 5am to head to the gym. 

And if you combine that with all the other quick dopamine fixes that lay waiting in the modern lifestyle, then that risk becomes more like an inevitability.

Dopamine’s Crucial Role In A Fitness Transformation

4. Gut Dysfunction

The gut is the first and most crucial line of defence against the toxins and pathogens of the outside world. Ingesting large amounts of fructose has been shown to cause bacterial overgrowth in the intestine and loosens the tight junctions in the gut lining.

This creates the state known as leaky gut, where compounds can pass undigested into the circulatory system, firing up autoimmune conditions and fostering high levels of inflammation.

Fructose further antagonises the situation by producing bacterial endotoxins and TMAO, an inflammatory compound that’s been unfairly associated with red meat consumption. Despite the fact the fructose and fish both have the ability to create much more.

How To Heal The Gut With A Carnivore Diet

5. Inflammation From Plant Toxins, Pesticides, And Seed Oils

why protein bars are unhealthy

Ultra processed foods like chocolate bars, soda and cookies are typically sweetened with sugar concoctions like high fructose corn syrup (HCFS). They also happen to be great candidates for seed oils, which are the preferred form of fat for processed foods, since they have a supposedly long shelf life and are categorised as heart healthy.

In reality, seed oils are a dizzying cocktail of metabolic poison. They are highly oxidative, create inflammatory cascades, form innumerable toxic by-products, and take the place of fats that would normally provide critical vitamins.

Meanwhile, unprocessed starches are typically low in seed oils, but come with plant toxins like lectins and gluten, which can further antagonise the situation in the gut by eroding the intestinal barrier.

Grains are also prime sources of pesticides like glyphosate, are carcinogens that strip nutrients, disrupt the endocrine system, and cause mitochondrial damage.

This should make a box of Honey Nut Cheerios look a little less tantalising.

The point here is that sugar generally doesn’t come in isolation, but packaged with other ingredients that each have their own insidious effects on your physiology.

If your only source of fructose is from fruit, and you only dabble in low toxicity starches like white rice, then you’ll have a lot less to worry about. But unfortunately that isn’t the usual way we get sugar in the modern diet.

6. Nutrient Depletion

sugar nutrition

The dietary requirements for carbohydrates in the diet is zero. The few tissues in the body that need glucose can easily source it from gluconeogenesis, glycerol, and recycled lactate. The remaining demands are met by triglycerides and ketones.

Dietary glucose, or carbs, are surplus to requirements.

Beyond glucose, carbs simply don’t offer much when compared to animal products. Even when they come in the guise of whole natural foods.

Plants ultimately lack bioavailability, and even then, don’t provide the full spectrum of nutrients needed to make us thrive. Plant toxins can further compound that problem by blocking the absorption of key minerals like iron, zinc, and calcium.

So the issue isn’t just the direct metabolic damage that sugar wreaks, it’s also the lack of nutrition that it brings to the party, making it liable to open up deficiencies that cause inflammation and dysfunction.

7. Insulin Resistance

Pathological insulin resistance is a state that underlies metabolic dysfunction, and creates a breeding ground for chronic disease. We’ve already tackled one potential mechanism by which excess sugar can lead to the development of insulin resistance: glycation.

The second one is uric acid, which I’ve covered in a previous article about the merits of adding fruit and honey to carnivore.

Uric acid is a by-product of fructose metabolism, and amongst other effects, increases insulin resistance. Once again, this situation likely only becomes problematic when fructose arrives as an avalanche rather than a trickle. When you’re eating an apple, there’s not a ton of fructose to begin with, and that fructose is slowed further by the accompanying fibre.

When you’re drinking a can of coca cola that’s loaded with HCFS, then that’s an altogether different situation.

8. Fat Storage

fructose effect on fat gain

This is where the ‘settled science’ crew will wave their pubmeds frantically and say that fat gain is merely a calorie equation. But that’s simplistic, and it neglects a couple of core issues.

1. Food ingested doesn’t mean food absorbed

2. Some foods are easier to overeat on then others

3. Lipolysis is often restricted by insulin resistance.

Now let’s see how fructose fits into this paradigm.

1. Fructose is limited in metabolism and storage, due to it being funnelled through the liver rather than being directed towards the much larger muscle sink. So it’s more likely to end up being surplus to requirements and entering De novo lipogenesis, which is the conversion of sugar to fat.

2. Fructose is metabolised by fructokinase, which has no negative feedback loop (likely due to the limited need for digesting large amounts of fructose across our evolution), allowing it to rapidly burn through ATP reserves, meaning you’re back to needing more fructose. Then there are the addictive properties of fructose, and the way it increases the hunger hormone ghrelin.

3. Fructose can lead to, or at least amplify, insulin resistance through high uric acid levels. High levels of insulin in the bloodstream will act as a persistent block on lipolysis.

So while I wouldn’t go as far as to discard the calorie equation entirely, and fructose certainly makes you more likely to overeat on calories, it also encourages fat storage in a way you simply don’t see in animal products.

9. Lowered Energy Levels

downsides of cardio

Sugar is a sedative, and here’s why.

Sugar blunts the effects of the stress hormone cortisol, leading lower levels in response to stressors, and lower peaks. This is part of why sugar is treated as a comfort food, a tonic to ease whatever suffering people are going through.

The issue with using food as comfort, however, is that you’ll be receiving a temporary uptick in mood that will swiftly fade and result in prolonged discomfort that will once again pull you back to the inviting grasp of the sugar drip.

There will be a few reasons why sugar leads to more misery. A few we’ve already touched on, such as dopamine depletion and the blood sugar rollercoaster, which itself will reflexively raise cortisol levels in response to the hypoglycaemic energy crisis.

But by suppressing the natural daily peak of cortisol in the morning hours, you’ll be reducing your alertness and focus in those early hours that would otherwise prime you for productivity. The absence of a healthy peak will also lead to cortisol levels being elevated in the evenings, which doesn’t bode well for your ability to have deep and revitalising sleep.

10. Cancellation Of Ketosis

Ketosis is our metabolic advantage. We can enter it easier than any other species, without a need for a calorie deficit. The ketones don’t just provide fuel, they exert many signals that, amongst others, upregulate antioxidative defences, reduce inflammation, and lower appetite.

But having your liver glycogen levels topped up puts an abrupt stop to those magical effects. When sugar is allowed to dominate the macros, triglycerides play second fiddle, and ketones are non-existent.

This is why the conventional approach for a ketogenic diet is to keep the carb intake below 50 grams, while sedentary people would be best served keeping it below 30 grams.

11. Accelerated Ageing

ageing by sugar

Sugar doesn’t just make you age by damaging the protein in your skin through glycation. That’s just the superficial effect. Underneath the surface, a diet laden with sugar can have wide-reaching implications by overloading the mitochondria’s electron transport chains and increasing the production of reactive oxygen species (ROS).

ROS is a form of oxidative stress that is designed to act as a signal for the body to ramp up energy production. It’s a natural process that can spiral up to damaging levels when the electron transport chains are overloaded with incoming glucose.

Excess ROS production can damage the mitochondria beyond the body’s ability to repair, which then creates dysfunction in whatever organs and processes those mitochondria are powering.

That is ageing in a nutshell. It’s not driven by time, it’s driven by the erosion of your precious mitochondria by oxidative stress. I’ve already done a deep dive before into the mitochondrial theory.

This situation is going to be further compounded if you’re filling up the mitochondrial membranes with brittle Omega 6, and creating oxidative cascades with rancid seed oils. That’s possibly the best example we have of why sugar and seed oils shouldn’t mix.

Wrapping Up

What this article should illustrate is that while sugar isn’t necessarily problematic when the dose is controlled, that dose gets out of control very easily when you indulge in grains and ultra processed foods. And through the incessant surges of hyperglycemia and hypoglycemia, the body takes a profound beating that can manifest in all manners of unsavoury symptoms.

This is why some of the benefits of a ketogenic diet like carnivore is going to be down to the stabilisation of blood sugar, and the side-stepping of the downstream consequences of the rollercoaster.

That isn’t the whole picture. The absence of seed oils and lowering of pesticide exposure make for monumental shifts by themselves. As does the influx of total nutrition, and the hormetic upgrades of ketosis.

But getting your sugar under control is always going to be a huge win.

The Four Insidious Ways Seed Oils Destroy Your Health

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