alt Hacker NewsAs you lose weight, your body needs fewer calories to run. That “needed amount” keeps dropping with your size, until it eventually equals what you’re eating on the medication. At that point you’re no longer in a deficit, so weight loss slows or stops.
That is true but requires some extra assumptions to explain why people don't keep losing weight - because the strongest influence on most people's appetite in the short run is how much of a deficit or surplus they're currently in. Thus as TDEE drops, so does hunger.
In "setpoint theory" there's an additional hunger drive based on whether you are below or above a given level of adiposity - your "setpoint". This is often given as an explanation for why people can't keep weight off, and is the sort of thing you'd need to posit to explain why people on GLP-1 inhibitors can't as easily get to lower levels of adiposity.