Are you a stress eater? Does an upcoming test or imminent work deadline send you careening toward the bottom of a bowl of ice cream or a bag of potato chips?

Physicians and dieters alike have long known that stress can prompt overeating. But now scientists have an explanation for why.

Neuroscientists know that the brain produces endocannabinoids (endo-can-uh-bin-oids), which are chemicals that help brain cells talk to each other. These neurotransmitters are busy in the hypothalamus — the part of the brain that regulates appetite, metabolism and manages the organ’s response to stress.

Scientists at the Hotchkiss Brain Institute in Alberta, Canada found that when they took food away from rats, a series of reactions unfolded, creating what scientists describe as a temporary rewiring of the brain. And that rewiring impaired the endocannabinoids’ ability to regulate food intake.

Dieters experience the frustration of this brain response. When they try to cut back on calories and deprive themselves of food, the stress causes the brain to transmit hunger signals.

The dieter might not be hungry, but the hypothalamus thinks it is.

This research could create hope for frustrated dieters. In the same study, scientists found that when the effects of stress hormones were blocked in the rats, taking food away did not cause their appetites to rev up.

What does this mean for obese and overweight people trying to lose some pounds? Researchers aren’t yet sure of the implications, but one tip nutritionists have been extolling for years might have found its scientific basis in this study. Planning your meals in advance can help your brain know where its next meal is coming from, perhaps subverting a bit of the stress.

A bit of forethought can help a dieter steer clear of the faulty rewiring that puts the appetite center of the brain in overdrive.