There's actual biology behind the "I just don't feel like drinking anymore" thing people report on retatrutide and the other GLP-1 class drugs. It's not placebo and it's not just because you're eating less, although that plays a role too.
The main mechanism is central. GLP-1 receptors are expressed in the mesolimbic dopamine system, specifically the VTA and nucleus accumbens, which is the same reward circuitry alcohol hijacks to produce its buzz. When you're on a GLP-1 agonist, dopamine release in response to alcohol gets blunted, so the hedonic payoff just isn't there the way it used to be. You drink and your brain doesn't fire the reward signal properly, and over time the cue-driven craving fades because the behavior stops being reinforced. This is well documented in preclinical models and is showing up in human trials now, with semaglutide being studied specifically for alcohol use disorder. Retatrutide is a triple agonist (GLP-1 + GIP + glucagon) so the effect is probably even stronger, though dedicated AUD trials haven't been published yet.
On top of that, these drugs slow gastric emptying significantly, which changes how alcohol is absorbed. Normally alcohol absorption depends on how fast it reaches the small intestine, and when the stomach empties slowly, the absorption becomes slower and more erratic. The rapid onset that makes drinking feel rewarding is essentially gone.
The worse tolerance part is where people get caught off guard. Several things stack at once. You're eating much less overall, so when alcohol does pass through there's less food buffering it. Dehydration is more common on these compounds because thirst signaling drops and you're consuming less fluid with smaller meals, and alcohol compounds that. The glucagon agonism (which is the unique piece of retatrutide compared to pure GLP-1 drugs) shifts hepatic metabolism and increases glucose output, and how that interacts with ethanol metabolism isn't fully characterized yet. And the same mechanism in the area postrema that suppresses appetite also lowers your nausea threshold, so a drink or two that used to do nothing can now genuinely make you sick.
The net experience is less desire to drink in the first place, less reward when you do, and worse physical consequences per gram of ethanol. Hangovers tend to be disproportionately bad for the amount consumed. Most people just naturally drift toward drinking much less or stopping altogether without trying. If you do drink, hydration matters more than usual and starting low is smart, because your old tolerance is not a reliable reference point anymore.
