Do you ever get that craving for something sweet after a meal? That urge to eat “something sweet” even when you’re already full?
In English, this is called “Dessert stomach,” and it appears to be linked to a specific group of nerve cells that release one of the body’s natural opioids.
Researchers at the Max Planck Institute for Biology of Ageing conducted a studyβnow published in Scienceβon mice and sugar (and later on human volunteers).
Notably, the animals’ reactions to the availability of sweets were striking: even completely full mice continued to eat the sugar available to them.
Brain investigations revealed that a group of nerve cells, the so-called POMC neurons, were responsible for this behavior. These neurons release signaling molecules that, on one hand, stimulate satiety but, on the other, also trigger a craving for sweets by releasing one of the body’s natural opioids, beta-endorphin.
Beta-endorphin, in turn, acts on other nerve cells (with opioid receptors), triggering a sense of reward that drives mice to eat sugar beyond satiety. Interestingly, these POMC neurons became active even before the mice had eaten the sugarβjust by perceiving it.
Furthermore, beta-endorphin was also released in the brains of mice that had never consumed sugar before. As soon as the first sweet solution entered their mouths, beta-endorphin was released and further strengthened by continued sugar consumption. When the researchers blocked this pathway, the mice refrained from eating sugar.
Another key finding was that this opioid pathway in the brain was not activated when the mice ate regular or fatty food. The effect was only observed in full animals, not in hungry ones.
The researchers also conducted brain scans on human volunteers who ingested a sugar solution through a straw and discovered that the same brain region was activated as in mice.
“From an evolutionary perspective, this makes sense: sugar is rare in nature but provides quick energy. The brain is programmed to ensure sugar intake whenever it is available,” explains Henning Fenselau, research group leader at the Max Planck Institute for Metabolism Research and lead author of the study.
These findings could be useful for developing drugs to treat obesity.
What is confirmed is that sweet foods, especially those where sugar is not naturally present (such as in milk and fruit) but added, are “addictive” and create a real dependence in both the body and the brain.
A few years ago, researchers from the Max Planck Institute, in collaboration with Yale University, demonstrated that foods high in fats and sugars alter our brains: if we regularly consume even small amounts, our brains will learn to crave them in the future, making it difficult to stop.
“Our brain, when faced with artificially concentrated nutrient-rich foods, develops adaptation and addiction mechanisms very similar to those seen with substances of abuse such as alcohol, nicotine, or drugs,” explains Dr. Stefano Erzegovesi, a medical nutritionist and psychiatrist.
An “addictive” food is characterized by high amounts of salt, sugar, and fat, as found in many industrially processed products, both sweet and savory. “Our brain is still too similar to that of our ancestors (who were selected to survive famines) to handle the impact of foods that are so concentrated in salt, sugar, fat, and appealing textures like softness or crunchiness, making them quickly ‘addictive’,” adds the psychiatrist.
However, completely banning these foods could trigger the opposite problem: binge eating. “Instead, we can try to ‘train’ our palate gradually (but daily) to less intense colors, flavors, and textures. For example, if we put 4 grams of sugar instead of 5 in our coffee, our palate will hardly notice. The same applies when reducing salt and fat intake. The only necessary ingredient for gradual change is taking a little more time to chew the food we eat: we donβt need to chew like Zen monks, but simply try chewing a bite 10 times instead of swallowing it almost immediately.”