What does sugar do to the body?

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The human body, especially the brain, needs sugar. However, we’re not talking about the industrial sugar found in huge quantities in processed foods, but rather the sugar obtained from foods like rice. Read on to find out how much sugar is healthy and what happens to the body when we eat too much of it.

What is sugar made of?

To answer this question, a distinction must be made between the different types of sugar, as not all sugars are the same. So what are the different types?


Examples of monosaccharides are glucose and fructose. They consist of a single sugar building block. Only monosaccharides can be absorbed directly into the bloodstream. All other types of sugar must be broken down into monosaccharides first. The immediate absorption of monosaccharides into the blood causes blood sugar levels to soar.


Disaccharides consist of two molecules. This type of sugar is also broken down quickly, but more slowly than monosaccharides. When we talk about sugar, we usually mean household sugar. But what exactly does household sugar consist of? It’s a disaccharide – made up of one molecule each of glucose and fructose.


Polysaccharides aren't made up of one or two molecules, but of an entire chain. This means that polysaccharides are broken down much more slowly than disaccharides. As a result, blood sugar levels rise only gradually and we stay full for a long time. Polysaccharides are found in foods like vegetables, rice and potatoes.

How disaccharides and polysaccharides are broken down

Disaccharides and polysaccharides must first be broken down into monosaccharides before they can be absorbed into the blood. This process begins in our saliva and we even notice it to a certain extent. Bread, for example, starts to taste sweet when we chew it for a while. This is because enzymes become active in our saliva that produce monosaccharides such as glucose from the carbohydrates in the bread. The carbohydrates are split down even further once they reach the small intestine. The resulting monosaccharides then pass through the intestinal wall into the blood.

How we obtain energy from sugar

The body constantly needs energy, so there’s always glucose floating around in our blood; the amount is measured as blood sugar. Sugar in the blood leads to the production and release of insulin. Insulin is responsible for stabilising blood sugar levels, which it achieves by removing sugar from the blood and transporting it to the cells of our organs. These use the sugar for energy.

Why does the body need sugar?

Our brain loves sugar. After registering that we’ve eaten something sweet, it rewards us with a feeling of happiness, because the monosaccharide glucose in sweet foods is particularly efficient at supplying the brain cells with energy. Our body needs sugar because, like oxygen, glucose is essential for ensuring the performance of basic bodily functions such as breathing, heartbeat and conscious thought. The brain therefore devours a large proportion of the glucose we consume.

Opt for foods containing polysaccharides

However, to supply our body with glucose, there’s no need for a direct intake of sugar, i.e. household sugar or sweetened foods and drinks. The sugar that’s essential for our survival is polysaccharide, which is found in foods such as vegetables, lentils and potatoes. These foods ensure that the body obtains glucose in a healthy way – not too much and not too quickly.

How many grams of sugar a day is safe?

The World Health Organisation (WHO) recommends that no more than 10% of our total energy intake should be covered by sugar. For adults with a requirement of 2,000 kilocalories, this amounts to around 50 grams of sugar a day. This corresponds to about 12 sugar cubes. One sugar cube is around 4 grams and contains about 16 kilocalories. But these are empty calories, as sugar provides no fibre, vitamins or phytochemicals. Reducing consumption down to around 25 grams of sugar per day would lead to additional health benefits.

Why do foods contain so much sugar?

Sugar is used as a flavour enhancer and acts as a cheap filler, a chemical binder or a preservative. For this reason, it’s always a good idea to read the list of ingredients printed on the packaging. The earlier sugar is mentioned, the more sugar the product contains. But watch out: sugar is often disguised in terms such as glucose, whey powder, corn syrup, lactose or maltose.

Ready-made products

Beware of ready-made products, as they often contain a lot of sugar that you wouldn't expect, especially when it comes to savoury foods. Examples include frozen pizza, ready-made tomato sauce, store-bought salad dressing, crisps and pickled gherkins. Don't be taken in by the surface flavour.

Low fat or extra high protein products

These – usually highly processed – products often contain a lot of sugar. This is partly to compensate for the loss of flavour in low fat products and partly to mask an unpleasant taste.

Smoothies are sugar traps

Smoothies are widely seen as healthy. However, for this to be true, they need to consist mainly of vegetables and only a small proportion of fruit. If fruit is the major component, then they’re packed with fructose instead. In addition, some of the fibre is lost when the fruit is processed. Fibre ensures that the sugar from the fruit is absorbed into the bloodstream slowly. When chopped or dissolved, the fibre can no longer perform this function properly.

Tips to reduce sugar consumption

  • Cook at home more often
    Consume fewer ultra-processed foods and ready meals. Instead of being rich in fibre, they’re full of added sugar.
  • Drink plenty of water
    Avoid soft drinks, juices and sweetened tea or coffee.
  • Eat plenty of fruit and vegetables
    Incorporate lots of fruits and vegetables into your meals. Both are healthy and keep you full for a long time. Fruit can help curb the craving for sweet foods.
  • Be careful with claims such as “with less sugar”
    As fructose tastes sweeter than household sugar, manufacturers cut down on sugar by using more fructose. However, this doesn’t make the product any healthier.
  • Ensure you relax and get enough sleep
    When we’re stressed and tired, we’re more likely to choose something unhealthy.
  • Use sugar alternatives
    Use natural sugar substitutes when baking and cooking.

Why is sugar unhealthy?

Too much sugar in the form of sweet foods can stress the body. This is because they contain sugar types that shoot into the blood very quickly. This causes the repeated release of insulin, the substance which transports the sugar in our blood to our organs. However, the organs may not be in need of a sugar supply. Because our cells can only absorb a certain amount of glucose, the excess sugar then remains in the blood. In consequence, the body may develop a resistance to insulin, meaning that the cells react less strongly to the messenger substance.

Effects of too much sugar

If the body has to work flat out for years due to excessive sugar consumption, it suffers from long-term stress and the risk develops of organs such as the heart, liver or kidneys becoming diseased. This may lead to permanently elevated blood sugar levels, a lipometabolic disorder, obesity or high blood pressure. The risk of cardiovascular disease and cancer increases as does the likelihood of a diagnosis of type II diabetes.

Excess weight

Excess sugar is stored in the liver and kidneys. With these stores, the organs can ensure that their cells are supplied with energy, even when the body isn’t consuming any. This is the case when we sleep, for example. When the stores are full, the body converts the sugar into fat.

Fatty liver

Fructose can only be processed in the liver. When fructose appears in excess, it's quickly converted into fat. This is why fructose often increases blood lipid levels and can lead to a fatty liver.


Too much sugar impacts the health of our teeth. Enzymes in the mouth convert the sugar into acids, which attack the tooth enamel. Over time, this can lead to tooth decay.

Digestive problems

A diet containing a lot of sugar can disturb the balance of our intestinal flora. This can lead to diarrhoea, flatulence and constipation.

Weakened immune system

People who eat too much sugar over a longer period of time damage their health and run the risk of becoming ill. This is because a high sugar consumption can weaken the immune system, as too much sugar promotes inflammation in the body.

Lack of drive and energy

If too much sugar enters the bloodstream at once, the pancreas releases a large amount of insulin. The result can often be an overreaction, which leads to a sharp drop in the body’s blood sugar level. This starts a vicious circle, as the low blood sugar level triggers a craving for even more sweets, and we feel weary and tired.

Other possible symptoms and medical conditions

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