“Just one drink” is a hopeful promise-turned-lie we’ve all uttered one too many times in our lives. But now, researchers from Texas A&M University have figured out the reason it’s so hard to cut yourself off after one pint or one glass of vino: our brains are actually wired to reach for another.

When alcohol enters your system, it affects the feel-good dopamine D1 neurons found in the part of your brain that controls motivation and reward systems, called the dorsomedial striatum. Researchers found that these D1 neurons actually change their shape when stimulated by booze, encouraging you to keep gratifying them with more liquid happiness. (Learn more about what’s going on with Your Brain On: Alcohol.)

The problem? The more you sip, the more activated the dopamine neurons become, encouraging you to indulge even more and continue a loop that’s hard for responsibility to pull you out of—which is what neurologically makes alcohol abuse so easy for some people to succumb to.