Brain link between stress and emotional eating

If you’ve had a near miss accident in your car or suffered the intimidation of a menacing person, you’ve probably felt it — a psychological reaction to a threat called a fight or flight response. Your heart rate climbs, anxiety washes over you, you might shake or sweat.

But hours after that stress passes, you may feel another response — a powerful desire for comfort food, that highly processed, high-fat stuff you know isn’t good for you. It can relieve stress and tension and provide a sense of control. Emotional eating following a stress-triggering interaction is familiar to many of us, and to scientists as well.

But how a threat signals your brain to want comfort food has been unknown.

Now, a scientist has pinpointed a molecule found in a region of the brain called the hypothalamus that is connected to changes in the brain that lead to emotional overeating. The team described the discovery in a paper published in Nature Communications.

“We don’t always eat because we are hungry and we have certain physical needs,” said the author. “Whenever we get stressed or feel some threat, then it can also trigger our eating motivation. We think this molecule is the culprit.”

The research team began their study by investigating a small molecule, Proenkephalin. This molecule is common in multiple parts of the brain, but little research had examined its role in the hypothalamus. The suspected it played a role in stress and eating because the hypothalamus is a center for regulating eating behavior.

The lab exposed mice to the odor of cat feces. The odor of a natural predator triggered a threat response in the mice, and 24 hours later, the mice exhibited a negative emotional state, overeating behavior, and neurons in their brains showed sensitivity to consumption of high-fat foods.

To confirm the role of the molecule in stress-induced eating, the researchers activated the same neurons artificially with light stimulating a genetically encoded molecule expressed in the neuronal cell’s membrane, without the predator scent, and saw a similar response. In addition, when they exposed the mice to the cat odor and quieted the reaction of the neurons expressing that molecule with the same technique, the mice showed no negative emotional state and didn’t overeat.

“So something about this molecule itself is very critical to inducing overconsumption after the threat,” the author said.

The discovery points toward a possible target for therapy to alleviate emotionally triggered eating.

“We have much more to learn about this molecule,” the author said, “but we found its location and it could be a good starting point.”