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Want to avoid making an impulsive, stupid choice that you’ll later regret? Eat something. When you’re starving, your stomach cranks out a hormone called ghrelin, and for the first time ever, researchers have proven that elevated ghrelin levels hinder both decision making and impulse control.

Although this study was done on rats, scientists from the University of Gothenburg in Sweden are fairly certain it works the same way in humans. They say that when ghrelin levels peak, hasty and straight-up dumb decisions tend to follow, oftentimes leading to little or no real reward. For instance, if you’re famished, you might stuff your face with a greasy burger and fries on the fly. Then you’ll feel sluggish and sick afterward. Or worse, if you’re car shopping or casually cruising the internet on an empty stomach, you could make an irrational purchase and wind up kicking yourself later.

According to the researchers, high ghrelin levels affect both parts of impulsivity. The hormone inhibits the body’s ability to resist responding physically to a temptation, and it also blunts the brain’s ability to wait for a reward rather than jumping on an opportunity that yields less benefit. To demonstrate these effects, the researchers trained lab rats to follow specific signals that directed them to either press a lever or resist pressing it in order to score a big reward: sugar. After the rodents knew the program, the scientists injected ghrelin directly into their brains to mimic signals of hunger sent by the stomach.

When juiced up with this hormone and given the signal to steer clear of the lever, most of the rats couldn’t resist and pressed it anyway. By going after instant gratification, they were denied the sugar reward. However, when not given ghrelin, the rodents were better able to abide by the no-go signals and leave the lever alone. The obedient, patient rats were later rewarded with sugar.

More studies need to be done on humans to firm up these findings, but they make a lot of sense. You know better than to grocery shop when famished, right? Studies have shown that people who hit the supermarket when hungry load their carts with all kinds unhealthy foods they wouldn’t otherwise buy. All that ghrelin coursing from the stomach to the brain could be the reason this happens.

So next time you’re faced with an important decision at work, for your family, or in your romantic relationship, be sure to have a sandwich before pulling any triggers.