Why do we still have an appetite for dessert when we are full? What kind of relationship exists between the "dessert stomach" and the brain's sugar control?

the reason why we still have an appetite for dessert when we are full and the relationship between the "dessert stomach" and the brain's sugar control are related to a group of neurons in the brain called POMC. Scientists from the Max Planck Institute for Biology of Ageing in Germany found through mouse experiments that these POMC neurons play a key role in the "dessert stomach" phenomenon. When a mouse is full and then eats extra sugar, these neurons will not only release signaling molecules that stimulate the feeling of fullness, but also release β-endorphins. This substance can activate the "reward system" in the brain, bringing a feeling of pleasure, so that the mouse will continue to consume sugar even when it's already full.
This "sugar addiction" mechanism is only activated when consuming sugar, and has no response to ordinary food or high-fat food. When scientists blocked this neural pathway through experiments, the mice no longer showed interest in extra sugar.
Interestingly, this mechanism is even activated before the animal actually eats the sugar. That is to say, just perceiving the presence of sugar is enough to trigger the brain's craving for sweets, and the "dessert stomach" will release β-endorphins, and consuming extra sugar will further enhance this release.
To verify whether this discovery applies to humans, scientists conducted brain scan experiments on volunteers. The results showed that when volunteers ingested a sugar solution through a straw, the same area in the brain as in mice was activated. This area is not only related to the feeling of fullness, but also rich in β-endorphins. So, the "dessert stomach" is related to the special function of these POMC neurons in the brain's sugar control mechanism, which makes us have an appetite for desserts even when full through the release of β-endorphins and activation of the reward system.