"Reward" is a must

Why we still crave sweets after a meal

"Sweets always work" is what many people think after an often sumptuous main meal, and researchers have now investigated why ...(Bild: stock.adobe.com/Atilio)

Who hasn't experienced it: after a hearty meal, you suddenly feel a craving for something sweet. The reason: the same nerve cells that trigger the feeling of satiety also play a role in why we crave sweets after a meal.

An international research team led by the Max Planck Institute for Metabolism Research in Cologne has investigated the scientific basis for this. The results show that the so-called "dessert stomach" is anchored in the brain. 

In the study, the researchers led by Henning Fenselau investigated the reaction of mice to sugar. They found that mice eat desserts even when they are completely satiated, as the team writes in the journal "Science". Investigations of the brain revealed that a specific group of nerve cells (POMC neurons) is responsible for this.

Rewarding feeling through sweets
When mice are full and eat sweets, these nerve cells not only release messenger substances that signal satiety, but also an endogenous opiate (the ß-endorphin). This triggers a feeling of reward that causes the animals to eat even more sugar. In the experiments, the mechanism already started when the animals only perceived sugar without eating it.

Brain studies on test subjects showed that the same brain region reacts to sugar in humans. From an evolutionary point of view, this makes sense: sugar is rare in nature, but provides energy quickly. The brain is programmed to control the intake of sugar when it is available.

Treatment option for obesity
The results could be significant for the treatment of obesity. There are already drugs that block opiate receptors in the brain. However, weight loss is less than with weight loss injections.