When faced with stress, turning to high-calorie snacks may provide temporary comfort. However, researchers at the Garvan Institute of Medical Research in Sydney have revealed that this combination can have negative effects on health. Their research reveals that stress, along with calorie-dense comfort food, causes brain alterations that lead to increased eating, cravings for sweet and highly appealing foods, and weight gain.
The researchers observed that stress interferes with the brain’s natural response to satiety, resulting in continual reward signals that encourage people to eat more. This effect was detected in the lateral habenula, a brain area that normally suppresses these reward signals.
“Our findings reveal stress can override a natural brain response that diminishes the pleasure gained from eating—meaning the brain is continuously rewarded to eat,” says Professor Herzog, senior author of the study and Visiting Scientist at the Garvan Institute.
“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.”
The study, which was published in the journal Neuron, looked at how different brain areas responded to chronic stress in mice models fed varied diets. The lateral habenula, which regulates the brain’s reward response, remained dormant in stressed mice on a high-fat diet, according to the researchers. As a result, reward signals remained active, promoting enjoyable feeding while ignoring satiety cues. This phenomenon resulted in much greater weight gain in stressed mice fed a high-fat diet than in non-stressed mice.
The chemical NPY was discovered as a key factor in the weight gain process by the researchers. The activity of brain cells in the lateral habenula was altered by NPY, which was released by the brain in response to stress. By inhibiting NPY activity in these cells, the researchers saw a decrease in comfort food consumption and, as a result, weight gain.
Furthermore, the researchers performed a “sucralose preference test” in which mice were given the option of drinking water or chemically sweetened water. When compared to mice on the same diet but without stress, stressed mice on a high-fat diet consumed three times more sucralose. This suggests that stress not only increases the reward response while eating but also causes a need for sweet and appealing foods.
“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. But when experienced over long periods of time, stress appears to change the equation, driving eating that is bad for the body long term,” explains Professor Herzog.
The researchers emphasise the importance of stress as a key regulator of eating behaviours, capable of overriding the brain’s natural energy-balancing systems. They underline the significance of avoiding a stressful lifestyle and, if suffering from chronic stress, adopting a nutritious diet while putting junk food out of reach.