We’ve all been there. You’ve just finished a huge meal—perhaps at a birthday dinner—and your stomach is telling you there’s no room left. But then, someone brings out dessert, and suddenly, you find space for a slice of cake. Sound familiar? Well, it turns out dessert cravings aren’t just about willpower or habit.
See, researchers have discovered that the annoying cravings we often get for sweets—even when we’re full already—are a response of our body’s neurological systems. In fact, the same neurons in our brain that signal fullness also trigger cravings for sugar.
A recent study in mice, conducted by researchers at the Max Planck Institute for Metabolism Research, found that neurons in the arcuate nucleus of the hypothalamus—which is responsible for controlling appetite, metabolism, and hormones—release natural opioids that drive our dessert cravings.
These neurons are known as pro-opiomelanocortin (POMC) neurons. When released, they send signals to another part of the brain called the paraventricular nucleus of the thalamus (PVT), which is involved in regulating our body’s eating behaviors.
Scientists involved in this latest study monitored mice as they ate their usual food. After 90 minutes, the mice were full and ignored additional food. However, when the researchers introduced a sugary treat, like a dessert, something fascinating happened. The mice—which had ignored other food after reaching a certain level of fullness—gave in to their dessert cravings and went back for more.
Additionally, the researchers noted that neural activity between the hypothalamus and PVT quadrupled before the mice even took a bite. They say this suggests that dessert cravings aren’t triggered by eating sweets, but rather, by anticipation of eating them. In other words, the brain prepares for the sugar intake as soon as dessert is available.
To test this further, researchers used optogenetics, a technique that allows them to turn neurons on and off using light. When they blocked the POMC-to-PVT signals, the mice ate 40 percent less dessert. This, they argue, provides evidence that this brain pathway plays a key role in dessert cravings.
One ongoing theory is that sugar is a quick and efficient energy source that is much easier to convert into fuel than fats or proteins. The scientists believe this neurological response could be tied to human evolution. There may have been a time when our body needed quick and dirty fuel sources to keep energy levels high.
If true, it could explain why we’re driven to sugary foods—and why so many struggle with dessert cravings. It could also go a long way in helping to create new weight loss pills designed to actually work with the body instead of against it.
