How sugar changes our eating habits
Sugar manipulates our brains and increases our cravings for sweets
Sugar occurs naturally in fruit, vegetables and dairy products, but it is also often added to food. No more than 10 per cent of daily calorie intake should come from sugar, as excessive consumption can lead to obesity and diabetes. Measures to reduce sugar consumption include public education campaigns, labelling requirements, and potential sugar taxes. However, alternatives such as artificial sweeteners are not a sustainable way to reduce sugar cravings.
What is meant by “sugar”?
The term encompasses all monosaccharides and disaccharides, i.e. carbohydrate molecules composed of one or two building blocks. Examples include glucose, sucrose, fructose, lactose and maltose.
Which foods contain sugar?
Fruits and vegetables naturally contain sugar, primarily in the form of glucose and fructose. Milk and dairy products contain sugar in the form of lactose; for example (per 100 grams):
- Condensed milk: 13 grams
- Cow's milk: 5 grams
- Yogurt/quark: 3–4 grams
Sugar is added to many foods, especially processed foods, during the manufacturing process. This is known as 'free sugar'.
Examples of the amount of added sugars in foods (in grams per 100 grams or per 100 milliliters):
- Fruit gummies: 75
- Pound cake: 23
- Fruit nectar: 17
- Cola: 10 to 11
- Fruit yogurt: 4 to 22
- Children's food: 15 to 43
What is the maximum amount of sugar you should consume each day?
The World Health Organization (WHO) recommends that no more than 10 percent of daily energy intake should come from free sugars. For an average energy intake of 2,000 kilocalories, this corresponds to 50 grams of free sugars. This includes naturally occurring sugars from honey, syrup, and fruit juices. Lower maximum amounts are recommended for infants, children, and adolescents.
How much sugar do we consume each day?
Although the amount of free sugar in Germany has declined in recent years, it still remains well above the recommended limit of 10 percent of daily energy intake. According to the National Nutrition Survey, sugar accounts for about 14 percent of the diet among people aged 15 to 80, and between 16 and 18 percent among adolescents and young adults aged 15 to 24.
Why does the body need sugar?
Sugar, or more precisely glucose, is the primary source of energy for our cells. With the help of oxygen, glucose breaks down into water and carbon dioxide, releasing energy in the process. Any excess glucose can be stored as starch or fat.
Why is too much sugar a problem?
Cells need the hormone insulin, which is produced by the pancreas, in order to absorb sugar from the blood. If blood sugar levels remain consistently high, the body responds by producing more insulin. However, as the body's cells cannot absorb that much sugar continuously, they reduce the number of insulin receptors, thereby becoming increasingly resistant to the hormone. Consequently, blood sugar levels remain persistently high. Insulin also ensures that any excess sugar in the blood is converted into fat. Additionally, sugar activates the reward system in the brain. This increases our craving for sugar, leading us to eat even more. All of this means that the body is unable to regulate food intake and metabolism adequately. The consequences can include obesity and, ultimately, diabetes.
Why is it so important to reduce sugar intake in the fight against obesity and diabetes?
Sugar isn’t just high in calories on its own. It also indirectly increases the number of calories we consume, as it keeps boosting our cravings for sweets. Therefore, foods high in sugar cause us to eat more and, consequently, consume more calories. So cutting out sugar can have a dual effect on our weight.
Can you commit to eating less sugar?
Sugar alters the connections between nerve cells in the brain's reward system. This intensifies our craving for sugar, literally “burning” it into our brains. Consequently, it becomes increasingly difficult to control how much we eat. Therefore, being overweight has nothing to do with a lack of willpower or discipline.
Why don't people just stop eating when they're full?
Our lack of self-restraint when it comes to eating is an evolutionary legacy from our time as hunter-gatherers. Back then, a hearty meal could be followed by a period of hunger at any time, so it made sense to occasionally eat more than necessary as a precaution against lean times. In today's age of abundance, however, this can be fatal.
Why do we often still have such a strong craving for something sweet after a meal?
This phenomenon is known as the 'dessert effect'. Special nerve cells in the brain release neurotransmitters that signal fullness. However, these cells also produce endorphins, which activate the brain’s reward system and cause us to crave more sugar. From an evolutionary perspective, this makes sense, as it enables the body to absorb significant quantities of this vital nutrient, which would otherwise be scarce in nature.
Can a sugar craving be considered an addiction?
Excessive sugar consumption meets several criteria for an addiction. These include
- a strong urge to consume sugar (“craving”)
- the need to consume more and more sugar
- consuming sugar even when aware of its negative effects
What measures could be taken to reduce sugar consumption in Germany?
Changes in the brain make it very difficult for those affected to 'wean' themselves off sugar. It is easier if it doesn’t get to that point in the first place. To prevent this, consumers need to be aware of the dangers of excessive sugar consumption and know how much sugar is in food. A traffic-light labelling system for sugar content, for example, could provide greater transparency.
Why should the government intervene to reduce sugar consumption in Germany?
The changes that sugar causes in the brain limit a person’s ability to exercise self-control. As a result, people have only limited control over their eating habits. In addition, people with low incomes and low levels of education often have less access to information about healthy eating. There is also a special responsibility toward children, as they are unaware of the dangers of excessive sugar consumption and have less control over their eating habits.
Could voluntary measures by food manufacturers help reduce sugar consumption, or would a sugar tax be more effective?
As part of an agreement with the German federal government, nine food industry associations have made a voluntary commitment to reduce the sugar content of their products. For example, the German Non-Alcoholic Beverages Association (Wirtschaftsvereinigung Alkoholfreie Getränke e. V.) has set a goal of reducing the sugar content of its soft drinks by 15 percent between 2015 and 2025. An analysis has shown, however, that sugar content decreased by only 2 percent between 2015 and 2021, rather than the 9 percent reduction planned for that period. It therefore seems questionable whether the sugar content of processed foods and beverages can be reduced on a voluntary basis.
In 2023, researchers calculated the potential impact of various tax options on sugary drinks. Their analyses showed that a 20 percent tax on sugary drinks could reduce sugar consumption among the adult population in Germany by 1 gram per day if retailers passed the additional costs on to consumers. A tiered tax that would lead to a 30 percent reduction in sugar content could reduce sugar consumption by more than 2 grams per day. Between 130,000 and 240,000 cases of diabetes could be prevented or delayed over the next 20 years. This would result in savings of €9.6 billion or €16.0 billion during this period.
46 professional associations in Germany, as well as the Leopoldina National Academy of Sciences, recommend imposing an additional tax on sugary drinks. There is also discussion about the VAT rate on sugar. Sugar is considered a staple food, to which a reduced tax rate of 7 percent applies.
How can I keep my sugar intake low?
Sugar is usually added to highly processed foods. Natural foods therefore generally contain less sugar than ready-made meals. So the rule is: it’s better to cook at home than to eat fast food! Beverages can also contain a lot of sugar. By choosing water over fruit juices and sweetened sodas, you can also reduce your sugar intake.
Are sweeteners a substitute for sugar?
Although sweeteners such as saccharin, aspartame, or stevia are much sweeter than sugar, they do not affect blood sugar levels and contain no calories. The sweetness of sugar substitutes (sugar alcohols) such as sorbitol, mannitol, or xylitol (“birch sugar”) is comparable to that of sugar, but they contain fewer calories and have less of an effect on blood sugar levels.
| Table sugar | Sweeteners | Sugar substitutes | |
|---|---|---|---|
| Calorie content (per gram) | 4 | 0 | 2,4 |
| Sweetness Power | 1.0 | 40 - 25,000 | 0.3 - 1.0 |
| Effect on blood sugar levels | High | No impact | Low |
If the brain waits in vain for sugar, it craves more. Despite having little effect on blood sugar levels, sugar substitutes stimulate the appetite because their sweetness triggers the brain’s expectation of sugar. That is why they do not help curb the craving for sweets.
Sources:
Bewertungen und Empfehlungen zur Reduktion des Zuckergehalts des Max Rubner-Instituts 2016
Leopoldina Fokus Januar 2026: Wie lässt sich die Adipositas-Epidemie eindämmen?
