Hormonal changes
GLP-1 is a hormone that interacts with your brain and gut to create a feeling of fullness. It does this in several ways, one of which is by suppressing the levels of ghrelin, the hunger hormone.
Ghrelin signals your brain when your stomach is empty, indicating that you need to eat, which is why it's often referred to as the hunger hormone. High levels of GLP-1 reduce ghrelin levels, leading to appetite-suppressing effects, so you’ll feel full and satisfied.
Another important hormone in this process is leptin, which helps regulate hunger by decreasing appetite and promoting a sense of fullness. The effects of leptin are enhanced by GLP-1, making the overall appetite-suppressing effect more potent.
When you stop GLP-1, the suppression of ghrelin ends. As a result, ghrelin levels return to normal, causing an increase in hunger. Similarly, the enhanced appetite-suppressing effects of leptin also diminish. The rebound in hunger may feel more intense because your body has become accustomed to lower ghrelin levels while on GLP-1, making hunger feel stronger than it actually is.
Gastric changes
Delayed gastric emptying is a mechanism of GLP-1 that helps with weight loss. It slows how quickly food leaves your stomach, keeping it in longer, which helps create feelings of fullness.
It does this by sending signals to the stomach that slow its natural churning action, while also signalling to the brain to suppress appetite. When GLP-1 treatment is stopped, these effects wear off, returning the movement of the stomach to its usual levels. As food leaves the stomach more quickly, it can contribute to an increase in hunger. These changes also occur relatively quickly; the resulting increase in appetite may feel particularly noticeable or unfamiliar.
Food noise returns
Food noise is a term people use to describe persistent or intrusive thoughts about food, such as thinking about what to eat when you're already eating or craving food even when you’re not physically hungry. It’s different from physical hunger: you can still be physically full yet still want food.
GLP-1 medications appear to suppress food cravings and the mental load of food for many people. They affect the areas of the brain involved in appetite and reward, while also slowing gastric emptying and increasing physical feelings of fullness.
When you stop taking GLP-1, your appetite and food cravings return as the medicine wears off. Many people report aversions to ultra-processed food and alcohol while on a GLP-1, but when the medication wears off, you may begin to choose these foods and drinks again. This can make maintaining weight loss more difficult and may contribute to weight regain.
