Ever get to the end of a movie and realize that the extra-large popcorn you meant to just nibble has mysteriously disappeared…through your mouth?We eat out of habit all the time—popcorn at the movies, chips at a restaurant, holiday candy on the coffee table—and that mindless reflex can leave us popping more in our mouths than we meant to. An August 2011 study, published in Personality and Social Psychology Bulletin, has a solution to steady your hand.In the first part of the study, 158 participants ate stale or fresh popcorn while rating short videos in two different settings—a movie theater and a meeting room. The researchers were looking to see whether the movie theater (which is where you’d typically eat movie popcorn) might lead to more automatic eating habits than the meeting room (where popcorn is a novelty).QUIZ: What’s Your Eating Style?Turns out, it did. Participants in the movie theater condition—regardless of how hungry they felt or how much they liked popcorn—ate significantly more, even when the popcorn was seven days old.Next, they tested whether eating with your non-dominant hand (your left if you’re a righty and vice versa), might prevent mindless overeating. Habits form a familiar pathway in the brain, so any action that requires more thought can help disrupt a habit.The researchers found that simply switching hands put overeaters back in control, leading them to eat significantly less—as though they weren’t in the habitual setting at all. It even helped people focus more on hunger and flavor cues, so they were less likely to down seven-day-old popcorn.MORE: Outsmart Your Eating InstinctsNext time you head to the movies or face off against the holiday candy dishes, just eat with your other hand and you’ll come out on top.