It puts a finger on the scale. Which unfortunately lasts as long as the person takes the drug. What happens when they stop taking it, unless they were on some serious strength trailing, is that they will have lost all the muscle they need to burn the extra calories they will start to eat when they transition off the drug. Which means the weight comes back even faster.

The body has no mechanism to break down fat cells like it can muscle cells. So every fat cell they had before taking the GLP-1 will still be there after years of taking GLP-1. Like deflated balloons, just primed to absorb any extra calories.