In a groundbreaking study published in the journal Neuron, researchers from the Garvan Institute of Medical Research in Sydney, Australia have shed light on the connection between stress and our eating behaviors. The findings suggest that stress can effectively silence the brain’s natural response to satiation, leading to increased consumption of high-calorie “comfort foods.” This discovery may explain why individuals experiencing chronic stress often find themselves reaching for unhealthy, calorie-rich options.
The researchers focused their investigation on the lateral habenula, a region of the brain known to modulate reward signals and suppress the desire to eat when one is already full. They observed that stress has the ability to override this natural response, continuously rewarding the brain and encouraging further eating. “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,” explained Herbert Herzog, senior author of the study and a Visiting Scientist at the Garvan Institute.
To explore the various eating behaviours exhibited under stress, the researchers conducted experiments using mouse models. They studied how different brain areas responded to chronic stress while the mice were exposed to different diets. The results indicated that the lateral habenula was active in mice on a short-term, high-fat diet, effectively protecting them from overheating. However, when the mice were subjected to chronic stress, this brain region remained inactive, allowing reward signals to persist and encouraging pleasurable feeding, regardless of satiety.
The study further revealed a significant link between chronic stress and weight gain. Stressed mice on a high-fat diet gained twice as much weight as their non-stressed counterparts. The researchers identified the molecule NPY, naturally produced by the brain in response to stress, as a key factor contributing to this weight gain. By blocking NPY from activating brain cells in the lateral habenula of stressed mice on a high-fat diet, the researchers observed a reduction in the consumption of comfort foods, ultimately resulting in less weight gain.
Additionally, the study uncovered a craving for sweet, palatable foods driven by stress. Stressed mice on a high-fat diet consumed three times more sucralose (artificially sweetened water) compared to those on a high-fat diet alone. This suggests that stress may lead to an increased desire for sugary foods. However, this preference for sweetened water was not observed in stressed mice on a regular diet.
The implications of these findings are significant, as chronic stress has been implicated in promoting weight gain and obesity. “Crucially, we did not see this preference for sweetened water in stressed mice that were on a regular diet,” highlighted Herzog. The study serves as a reminder of the detrimental effects of stress on healthy energy metabolism and underscores the importance of adopting a healthy diet and avoiding junk food, especially in times of prolonged stress.
While some individuals may experience a reduced appetite during stressful periods, others find solace in high-calorie comfort foods. This research provides valuable insights into the complex relationship between stress and eating behaviours, paving the way for potential interventions to mitigate stress-induced weight gain and promote healthier choices in times of stress.
