Scientists Find Key Brain Connection in Stress-Induced Emotional Eating

If you’ve ever had a close call while driving or felt scared by someone, you might recognize that feeling—it’s your body’s way of reacting to danger, and it is called the fight or flight response. Your heart races, you get anxious, and you might start shaking or sweating. It’s like your body’s alarm system kicking in – leading to Stress-Induced Emotional Eating!

After the stress is gone, you might notice a strong craving for comfort food—the kind that’s packed with processed goodness and high in fat, even though you’re aware it’s not the healthiest choice, also known as Stress-Induced Emotional Eating. It has this amazing ability to ease stress and tension while giving you a comforting sense of control. Many of us, including scientists, can relate to turning to comfort food after a stressful encounter. But the big question has always been: How does a threat make your brain crave that soothing comfort food? It’s a bit of a mystery.

Recently, a scientist from Virginia Tech has identified a special molecule in a part of the brain called the hypothalamus. This molecule is linked to the changes in the brain that make us lean towards emotional overeating. The discovery was made by Sora Shin, an assistant professor at the Fralin Biomedical Research Institute at VTC, and her research team. They shared the details of their breakthrough in a paper published on October 28 in Nature Communications.

“We don’t always eat because we are hungry and we have certain physical needs,” said Shin, who is also an assistant professor in the Department of Human Nutrition, Foods, and Exercise in Virginia Tech’s College of Agriculture and Life Sciences. “Whenever we get stressed or feel some threat, then it can also trigger our eating motivation. We think this molecule is the culprit.”

Shin and her team kicked off their investigation by delving into a tiny powerhouse called Proenkephalin. Although this molecule is present in various parts of the brain, not much attention had been given to its role in the hypothalamus. Shin had a hunch that it might be connected to stress and eating, given that the hypothalamus is a control center for managing eating behavior.

In their lab experiment, they exposed mice to the not-so-pleasant scent of cat feces. This natural predatory odor set off a threat response in the mice. Surprisingly, 24 hours later, the mice showed signs of a negative emotional state and engaged in overeating, and their brain neurons became extra sensitive to high-fat foods.

To confirm the molecule’s role in stress-induced emotional eating, the researchers used light to artificially activate the same neurons using a genetically encoded molecule in the neuronal cell’s membrane. They did this without the actual predator scent and observed a similar response. Moreover, when they exposed the mice to the cat odor but quieted the reaction of the neurons expressing that molecule using the same technique, the mice didn’t display a negative emotional state and refrained from overeating.

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

This exciting breakthrough opens the door to a potential therapy target for easing emotionally triggered eating.

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

For more information: Lateral hypothalamic proenkephalin neurons drive threat-induced overeating associated with a negative emotional state, Nature Communications (2023). DOI: 10.1038/s41467-023-42623-6