What is sugar?

Sugar is the term for a group of simple carbohydrates that taste sweet and provide the body with quickly available energy. Chemically, these are compounds of carbon, hydrogen, and oxygen that the body can easily convert into glucose - the main source of energy for cells, the brain, and muscles.

In nutrition, a distinction is made between natural sugars, which occur in fruit, milk, or vegetables, and added sugar, which is added to foods during production or preparation (e.g., in sweets, baked goods, or soft drinks).

Sugar provides 4 kcal (17 kJ) per gram, but contains no vitamins, minerals, or fiber - which is why it is considered an “empty calorie” when consumed in large quantities.

Types of sugar

Sugar is divided into different groups according to its chemical structure:

1. Monosaccharides (simple sugars):

  • Glucose (grape sugar): the body's most important source of energy.

  • Fructose (fruit sugar): found in fruit, honey, and some vegetables.

  • Galactose: a component of milk sugar (lactose).

2. Disaccharides (double sugars):

  • Sucrose (table sugar): consists of glucose + fructose; the most common added sugar.

  • Lactose (milk sugar): glucose + galactose; a natural component of milk.

  • Maltose (malt sugar): is formed when starch is broken down.

3. Oligosaccharides and polysaccharides (multiple sugars):
These consist of many simple sugar molecules and are classified as complex carbohydrates (e.g., starch).

How does sugar affect the body?

1. Quick source of energy:
After consumption, sugar is rapidly absorbed in the small intestine and enters the bloodstream as glucose. Blood sugar levels rise, and the pancreas releases insulin to transport the glucose into the cells - where it is used directly to produce energy.

2. Brain function:
The brain relies particularly heavily on glucose. Consuming sugar in the short term can improve concentration and reaction time - too much sugar, however, can have the opposite effects, such as energy slumps and restlessness.

3. Impact on insulin and energy balance:
Frequent blood sugar spikes caused by consuming too much sugar lead to insulin fluctuations, which strain the metabolism and can trigger cravings. In the long term, this can lead to insulin resistance, obesity, and metabolic disorders.

4. Mood and reward:
Sugar activates the reward system in the brain by stimulating the release of dopamine - similar to other pleasurable substances. This explains why sugar makes you feel “happy” in the short term, but can also become addictive quickly.

Natural vs. added sugar

  • Natural sugar: occurs in foods such as fruit, milk, or vegetables and is accompanied there by fiber, water, vitamins, and minerals. This combination slows absorption and has a positive effect on health.

  • Added sugar: is processed industrially in foods (e.g. table sugar, glucose syrup, fructose, maltodextrin) and provides energy only, but no nutrients.

Benefits (in moderate amounts)

  • Quick source of energy for the brain and muscles

  • Supports performance during intense physical activity

  • May temporarily improve concentration and mood

  • In its natural form (e.g. fruit), it also provides vitamins and antioxidants

Risks of excessive sugar consumption

Persistently high sugar consumption is associated with numerous health problems, including:

  • Weight gain and obesity

  • Tooth decay caused by bacterial sugar breakdown in the mouth

  • Insulin resistance and type 2 diabetes

  • Fatty liver (non-alcoholic fatty liver disease)

  • Inflammatory processes and increased oxidative stress

  • Fluctuating energy and blood sugar levels

  • Increased risk of cardiovascular disease

Recommendations from nutrition societies

The World Health Organization (WHO) recommends that a maximum of 10% of daily energy intake should come from added sugar - ideally less than 5%.

This corresponds to approximately:

  • 25–50 g of sugar per day (6–12 teaspoons) for adults.

Sugar can hide behind many names, e.g. glucose syrup, dextrose, sucrose, maltose, invert sugar, fructose syrup - so it is worth checking the ingredients list.

Conclusion

Sugar is a natural part of our diet and provides quick energy - completely harmless in moderate amounts. It becomes problematic with excessive consumption of added sugar, as found in soft drinks, sweets, and processed foods. Using sugar mindfully means preferring natural sources such as fruit and reducing industrially added sugar. This keeps blood sugar levels stable, distributes energy evenly, and protects long-term health.

Sources

  1. World Health Organization (WHO). (2015): Guideline: Sugars intake for adults and children.

  2. German Nutrition Society (DGE). (2020): Sugar and dental health - DGE recommendations.

  3. Lustig RH, Schmidt LA, Brindis CD. (2012): Public health: The toxic truth about sugar. Nature, 482(7383), 27–29.

  4. Te Morenga L, Mallard S, Mann J. (2013): Dietary sugars and body weight: systematic review and meta-analyses. BMJ, 346, e7492.