A new study out of Australia reveals why people who are stressed crave calorie-dense comfort food. Stress appears to override the part of the brain that signals satiety, or feeling full, say scientists at the Garvan Institute of Medical Research. In fact, chronic stress can spark changes in the brain that boost cravings for sweets and other junk food.

According to Study Finds, this eating pattern can lead to unhealthy weight gain. The area in the brain that is affected by chronic stress is called the lateral habenula, the critical crossroad that influences the brain’s response to pain, stress, anxiety, sleep, and reward.

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“Our findings reveal that stress can override a natural brain response that diminishes the pleasure gained from eating — meaning the brain is continuously rewarded to eat,” said Herbert Herzog, an obesity expert and senior author of the study in a news release. “We showed that chronic stress, combined with a high-calorie diet, can drive more and more food intake as well as a preference for sweet, highly palatable food, thereby promoting weight gain and obesity. This research highlights how crucial a healthy diet is during times of stress.”

While some people eat less during stressful times, most eat more than usual, reaching for high-fat and high-sugar options. The team of researchers used mouse models to investigate brain response to chronic stress and various diets.

“We discovered that an area known as the lateral habenula, which is normally involved in switching off the brain’s reward response, was active in mice on a short-term, high-fat diet to protect the animal from overeating. However, when the mice were chronically stressed, this part of the brain remained silent allowing the reward signals to stay active and encourage feeding for pleasure, no longer responding to satiety regulatory signals,” explained Dr. Kenny Chi Kin Ip, from the Garvan Institute and first author of the study.

The researchers found that stressed mice on a high-fat diet gained twice as much weight as mice on the same diet who weren’t stressed.  The core cause of the weight gain was a molecule called NPY, which the brain produces naturally in response to stress. When the researchers blocked this molecule in the stressed mice on a high-fat diet, the animals gained less weight.

Another crucial finding was that the stressed-out mice on a high fat diet preferred water sweetened with sucralose over plain water. In fact, they consumed three times the amount of sucralose than the mice on a high-fat diet alone, suggesting that stress can trigger a craving for sweet, palatable food, said Herzog.

“We didn’t see this preference for sweetened water in stressed mice on a regular diet,” he noted.

“In stressful situations it’s easy to use a lot of energy and the feeling of reward can calm you down. This is when a boost of energy through food is useful,” Herzog explained. “But when experienced over long periods of time, stress appears to change the equation driving eating that is bad for the body long term.”

The study that appears in the journal Neuron identifies stress as a critical regulator of eating habits that can override the brain’s natural ability to balance energy needs, said the researchers.

“This research emphasizes just how much stress can compromise a healthy energy metabolism,” said Herzog. “It’s a reminder to avoid a stressful lifestyle, and crucially — if you’re’ dealing with long-term stress — try to eat a healthy diet and lock away the junk food.”