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How Does Sugar Affect Our Health?

Author: Forth

January 19, 2021


How does sugar affect our health

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A report by Public Health England in 2018 found that most people in the UK eat three times more than the recommended daily sugar intake. According to the NHS adults should have under 30g of sugar a day which is equivalent to 7 sugar cubes, that means most people are eating the equivalent of 21 sugar cubes a day!

It’s not just the obvious foods we should be careful about consuming, such as cakes, sweets, chocolate, alcohol and fizzy drinks. There are hidden sugars in other foods such as supermarket bread, pasta sauces, salad dressings, breakfast cereals and ready meals.

We take a look at the impact sugar has on the body and the associated health problems.

Is All Sugar Bad For Us?

In short, no, our bodies need sugar to breakdown into glucose which is used for energy production. It’s when we take in too much sugar through our diet that it starts to cause problems, particularly if it’s refined sugar.

The main source of energy for our body is glucose (blood sugar) which is produced when our body breaks down carbohydrates. Carbohydrates are made up of starch, fibre and sugar and there are two types, simple and complex.

The sugar element of carbohydrates is known as simple carbohydrates as the body breaks it down into glucose quickly to use for energy. This gives us our sugar ‘hit’ but can leave us zapped of energy once the body has used up the glucose.

The starch and fibre within carbohydrates are known as complex carbohydrates as the body takes longer to digest and break them down into glucose which provides a longer energy release than simple carbohydrates.

Simple carbohydrates come in both natural forms of sugar found in fruit, vegetables, and dairy products, as well as added sugar such as granulated sugar, and sugar found in cakes, sweets, chocolates, biscuits, alcohol, and fizzy drinks.

Complex carbohydrates are found in foods that contain starch and fibre such as bread, pasta, vegetables, whole grains, peas and beans.

Eating foods that are high in complex carbohydrates and low in refined sugar will help keep our energy levels in balance by providing our body with a slow release of glucose.

What Happens To Your Body When You Eat Sugar?

As mentioned above, when you eat carbohydrates, enzymes in our small intestine break the sugar down into glucose. The glucose is then transported via the bloodstream to the cells, tissues and organs that require it, so it can be converted into energy and used to help the body’s cells, tissues and organs to continue functioning effectively.

When our bodies produce too much glucose due to increased sugar intake, it will be stored as fat in the liver and muscles until our body needs to use it. However, if we consume too much sugar than our body can use, it can lead to weight gain and other health issues.

The hormone insulin also plays a key role within our body by allowing our cells to absorb the glucose and thereby regulating blood sugar levels.

How Does Too Much Sugar Affect Our Health?

So, we know that sugar in the form of simple and complex carbohydrates gives us energy, which is good.

But when we habitually consume too much sugar in our diet, then it can lead to a number of health issues.  However, it’s important to note that isolating any single food type as a cause of disease is risky and often inaccurate [1]. It can lead to limiting beliefs that can result in even more unhelpful behaviours such as following ‘fad’ diets such as Keto where high amounts of protein and fat is consumed, and low amounts of carbohydrates, thus cutting out the body’s main source of energy.

As sugar can be easy to overconsume, it can lead to an excess in energy intake, especially if this displaces other key nutrients. For those of us who are very sedentary, the excess energy, over time will be stored as fat and lead to becoming overweight.

Being overweight and obese we know can lead to other conditions such as heart disease, type 2 diabetes, and stroke.

Other health issues caused by a diet high in sugar include:

Fluctuating Blood Sugar Levels

Not having a healthy, balanced diet and one high in simple carbohydrates can cause blood sugar levels to fluctuate. This will give you an initial burst of energy but then a slump after eating, causing lethargy and hunger. 

Cognitive Function

A diet high in sugar can have a negative impact on our brain too. A recent study carried out by Imperial College London and reported by Diabetes UK found that those with high levels of blood sugar were more likely to suffer from poor memory and concentration as they aged.

The study involved more than 5,000 people aged over 50 who had their cognitive function tested every two years over a 10-year period. The study group had a mix of participants with and without diabetes. Regardless of whether diabetes was present in the participant, those with high blood sugar levels performed worse in cognitive tests.

Part of its conclusion was that managing blood sugar levels through diet and exercise will help keep your brain in good shape.

Fatty Liver

An increased intake of the processed version of fructose syrups often used in snack foods is associated with a fatty liver. Fructose is broken down by the liver rather than taken up by the cells and organs of the body like glucose.

Once in the liver, fructose is converted into energy or stored as glycogen, but once glycogen stores are used up, the excess is turned into fat. This can lead to non-alcoholic fatty liver disease. In the early stages, this disease doesn’t usually cause you any harm but if it is undiagnosed or gets worse it can cause serious damage including cirrhosis.

Mental Health Effects Of Eating Too Much Sugar

Having an unhealthy gut that does not have a well balance gut microbiome will have an effect on your brain due to the emergence of what’s known as the gut-brain axis. In addition, spikes in blood sugar levels can affect our mood, making us angry, irritable, and low.

Keeping blood sugar levels stable and ensuring a good, balanced diet to keep our guts healthy will also help improve our mood.

Again, it’s not about a single item of food, in this case sugar, but about the combination of foods we eat that will help improve our mental health.

What Are The Symptoms Of Too Much Sugar?

The most common signs of eating too much sugar will be weight gain and tooth decay. Mood swings, feeling tired and increased appetite are all due to blood sugar level fluctuations as a result of consuming too much sugar, or the wrong types of sugar e.g. simple carbohydrates vs complex carbohydrates.

High levels of blood sugar, also known as hyperglycaemia, can cause of a variety of symptoms including:

  • Increased thirst and dry mouth
  • Unintentional weight loss
  • Recurrent infections, particularly bladder and skin infections
  • Blurred vision
  • Fatigue
  • Increased need to urinate
  • Stomach pain, feeling or being sick
  • Bad breath (breath smells fruity)

Hyperglycaemia is common for people with both type 1 and type 2 diabetes.


We all need sugar in the form of simple and complex carbohydrates to enable our body to produce glucose to give us energy. However, an overall poor diet that is high in sugar, as well as fat and salt can contribute to poor health outcomes such as an increased risk of heart disease, stroke, obesity, and diabetes.

Ensuring your diet has a good balance of simple and complex carbohydrates, accompanied by a good exercise regime will keep your blood sugar levels in check, ensuring your body is able to release energy throughout the day. Avoiding blood sugar level spikes due to eating sugary foods or consuming drinks high in sugar will help improve your energy levels and mood.

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Article references

  1. Crane, P, K et al. (2013). Glucose Levels and Risk of Dementia. The New England Journal of Medicine: 369, pp 540-548.

  2. Gangwisch, J, E et al. (2015). High Glycemic Index Diet as a Risk Factor for Depression: Analyses from the Women’s Health Initiative.

  3. Guo, X et al. (2014). Sweetened Beverages, Coffee, and Tea and Depression Risk Among Older US Adults. PLoS One: 9(4).

  4. Seneff, S et al. (2011). Is the Metabolic Syndrome Caused by a High Fructose, and Relatively Low Fat, Low Cholesterol Diet? Arch Med Sci: 7(1), pp 8-20.

  5. Yang, Q et al. (2014). Added Sugar Intake and Cardiovascular Diseases Mortality Among US Adults. JAMA Intern Med: 174(4), pp 516-524.

This article was written by Forth