Chronic stress causes the brain to crave comfort food

In moments of intense stress, many of us fall into the trap of indulging in high-calorie snacks. While this may seem pretty harmless, scientists have now discovered that the combination of chronic stress and comfort food instigates a series of changes in our brain. These changes drive us to eat more, intensify our cravings for sweet food, and eventually result in excessive weight gain.

A research group from the Garvan Institute of Medical Research has conducted an innovative study showing how chronic stress has the power to disrupt the brain’s natural response to fullness. In particular, the scientists pinpointed alterations within a brain region known as the lateral habenula. Ordinarily, when activated, the lateral habenula acts to suppress reward signals associated with 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,” said study senior author Professor Herbert Herzog. “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.” 

Professor Herzog also stressed the importance of maintaining a healthy diet during periods of stress, a key implication of their research. The findings have been published in the journal Neuron.

How does the brain react to chronic stress?

The team delved into the curious phenomenon where most individuals tend to eat more and select calorie-dense options high in sugar and fat when subjected to stress. However, this is not a universal response, as some people may experience decreased appetite under stressful conditions. 

To dissect these disparate eating habits, the scientists studied how different areas in the brain reacted to chronic stress under various dietary regimes using mouse models.

“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 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 study first author Dr. Kenny Chi Kin Ip.

As a result, he disclosed that mice exposed to chronic stress while on a high-fat diet gained double the weight compared to those on the same diet without stress.

At the heart of this weight gain was the molecule Neuropeptide Y (NPY), which the brain naturally generates in response to stress. When the researchers blocked NPY from activating brain cells in the lateral habenula of the stressed mice on a high-fat diet, the mice exhibited a reduced intake of comfort food and consequently less weight gain.

Chronic stress leads to an unhealthy diet

The researchers further unraveled the complex relationship between stress and diet preferences using a “sucralose preference test.” This involved giving mice the choice to drink either water or artificially sweetened water.

“Stressed mice on a high-fat diet consumed three times more sucralose than mice that were on a high-fat diet alone, suggesting that stress not only activates more reward when eating but specifically drives a craving for sweet, palatable food,” said Professor Herzog. Interestingly, this predilection for sweetened water was not observed in stressed mice following a regular diet.

“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,” explained Professor Herzog.

The findings indicate that stress is a key modulator of eating habits, capable of overpowering the brain’s inherent capacity to maintain energy equilibrium. In essence, the research suggests that prolonged stress conditions can lead to unhealthy dietary habits and metabolic complications.

Professor Herzog concluded by reinforcing the importance of a healthy lifestyle and diet, particularly under persistent stress conditions: “This research emphasises just how much stress can compromise a healthy energy metabolism. It’s a reminder to avoid a stressful lifestyle, and crucially – if you are dealing with long-term stress – try to eat a healthy diet and lock away the junk food.”

More about chronic stress 

Chronic stress is a prolonged and constant feeling of stress that can negatively affect one’s health if left unmanaged. It is different from acute stress, which is a normal reaction to changes and challenges in daily life. While acute stress can even be beneficial or motivational in short bursts (known as the ‘fight-or-flight’ response), chronic stress can be detrimental.

Key aspects of chronic stress:

Causes

Chronic stress can be caused by various factors such as ongoing work pressure, financial strain, challenging relationships, chronic illnesses, or constant exposure to a stressful environment. Sometimes, an accumulation of small stressors can also lead to chronic stress.

Effects on the brain and body

Chronic stress releases stress hormones like cortisol over an extended period, which can impact the brain’s structure and function. This can lead to alterations in mood, decision-making, and the way one handles further stress. It also impacts physical health, contributing to issues like heart disease, digestive problems, sleep disorders, weight gain, and a weakened immune system.

Psychological consequences

Chronic stress is associated with mental health disorders such as depression, anxiety, and post-traumatic stress disorder (PTSD). It can cause feelings of frustration, anger, irritability, and hopelessness.

Behavioral changes

People experiencing chronic stress might develop unhealthy coping strategies like overeating (as highlighted in the study conducted by the Garvan Institute of Medical Research), smoking, alcohol consumption, or drug abuse.

Management and coping strategies

Managing chronic stress typically involves lifestyle changes. This includes incorporating regular physical activity, maintaining a balanced diet, ensuring adequate sleep, and adopting relaxation techniques such as meditation, deep breathing, or yoga. It is also important to build a strong support system through friends, family, or professional counseling.

Professional help 

Sometimes, chronic stress can be overwhelming, and individuals might need professional help. This can range from counseling and therapy (such as cognitive behavioral therapy) to medication in some cases.

Understanding and acknowledging the impact of chronic stress is essential for well-being. It’s important to recognize its signs and symptoms early and to adopt healthy coping strategies or seek professional help if necessary. By doing so, one can mitigate the adverse effects of chronic stress on both mental and physical health.