Have you ever finished a big meal, feeling completely full, only to find yourself reaching for dessert? Scientists from the Max Planck Institute for Metabolism Research have discovered that this craving for sweets, often called the “dessert stomach,” is controlled by the brain. The same nerve cells that make us feel full also play a role in making us want sugar afterward.
The Science Behind the “Dessert Stomach”
To understand why we still want sweets after a meal, researchers studied mice. They found that even when the mice were full, they still ate sugar when given the chance. The reason? A special group of brain cells called POMC neurons.
These neurons, which normally signal fullness, also become active when sugar is available. Instead of stopping food intake, they actually encourage the mice to eat more sugar.
When the mice ate sugar, these neurons released β-endorphin, a natural opiate produced by the body. This chemical interacts with opiate receptors in the brain, creating a pleasurable, rewarding feeling. This reward system explains why the mice continued eating sugar even when they weren’t hungry.
Sugar, Not Just Any Food, Triggers the Reward System
Interestingly, this brain response was specific to sugar. When the mice were given regular or fatty food after a meal, the reward system was not activated. But when sugar was available, the β-endorphin release triggered a strong desire to keep eating.
To confirm their findings, the scientists blocked the opiate pathway in the mice’s brains. When this happened, the mice stopped eating sugar once they were full. However, in hungry mice, blocking the pathway had no effect—showing that this system is mainly responsible for sugar cravings in already full animals.
Even more surprisingly, the effect started before the sugar was even eaten. When the mice smelled or saw sugar, their brains already began releasing β-endorphins in anticipation. And in mice that had never eaten sugar before, the reaction still happened as soon as sugar touched their tongues. This suggests that the brain is wired to recognize sugar as a special kind of food.
What About Humans?
To see if the same process happens in humans, the researchers conducted brain scans on volunteers who were given sugar through a tube. The scans showed that the same brain region that responded in mice was also activated in people. Just like in mice, this area contained many opiate receptors near the neurons that signal fullness.
From an evolutionary perspective, this response makes sense. “Sugar is rare in nature, but it provides quick energy,” explains Henning Fenselau, the lead scientist of the study. “The brain is programmed to encourage sugar intake whenever it is available.”
This might have been useful for survival in the past but could now contribute to overeating in modern diets where sugar is easy to find.
What This Means for Obesity Treatment
The study’s findings could help improve treatments for obesity. Some existing drugs block opiate receptors in the brain, but they have not been as effective for weight loss as other appetite-suppressing treatments. Researchers believe that combining these drugs with other therapies could be more effective in controlling sugar cravings and overeating.
For now, the research shows that our love for dessert is more than just a habit—it’s deeply rooted in brain chemistry. While it once helped humans survive in food-scarce environments, in today’s world of endless sugary options, it may be working against us.
If you care about nutrition, please read studies about why vitamin K is so important for older people, and this snack food may harm your heart rhythm.
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The research findings can be found in Science.
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