You are likely well aware of the link between mental health and eating habits — but how does stress affect appetite? For some people, the prospect of exams or difficult conversations can effectively put them off food for days on end, while for others, mental health battles will trigger the need for comfort eating and perhaps even binges. But what exactly causes us to behave this way? Is it rooted in our biology, or is stress eating more linked to upbringing and individual psychology?
Here, we’ll look at what science says about the phenomenon of comfort eating, and what we can do to stop it from happening. At the same time, it needs to be stressed that it may be hard to put a finger on the exact cause of stress eating. As scientists from the Hormones and Behavior (opens in new tab) point out, there is no established diagnostic criteria for this behavior. Not to mention, everyone perceives stress, emotions, and even hunger cues differently.
How does stress affect appetite and eating behaviors?
Stress is a powerful physiological and psychological state. In fact, it can alter our metabolism, increase our susceptibility to infections, worsen our cardiovascular health and, unsurprisingly, take a huge toll on our mental wellbeing.
Since our brain and our gut are in constant communication (the so-called gut-brain axis), stress can also have a big impact on our appetite and eating behaviors. And studies have shown that this connection can develop very early on. According to one study published in the Appetite (opens in new tab) journal, children as young as eight to nine years old can show signs of comfort eating when exposed to high levels of stress. This is of particular concern, as unhealthy eating behaviors developed in early years are likely to persist into adulthood.
There are two main types of stress: acute and chronic. Acute stress is a response to a sudden, intense, and often unexpected stressor. Chronic stress, meanwhile, may be less intense, but it lasts for much longer, and may be more related to personal circumstances. It is crucial to make a distinction between these two states, as they will not have the same effect on our bodies. And according to the Nutrition (opens in new tab) journal, they may also have a different impact on our eating behaviors.
Chronic stress appears to be more linked to greater intakes of foods that are high in calories, sugars and fat, whereas acute stress is more likely to suppress the appetite and generate the sensation of a ‘tight stomach’. However, this is not an absolute rule.
Appetite control is complex. To a significant extent, it is controlled by hunger hormones like ghrelin and leptin. Ghrelin is known as the appetite-stimulating hormone. According to a study in the International Journal of Molecular Sciences (opens in new tab) reduced ghrelin levels have been detected in anorexic animal models, as well as human subjects taking anticancer drugs and certain antidepressants of which the main side effect is appetite loss. This hormone tends to decrease in response to acute stress, and rise in response to chronic stress. Studies done on mice have also shown that if you subject these animals to chronic social defeat and isolation stress, their ghrelin levels and food intake will increase significantly.
At the same time, not all mice will eat more when they are exposed to stressors, even if their ghrelin levels are elevated. Scientists point out that animals (and potentially humans as well) can develop so-called ‘ghrelin resistance’, depending on the type of stressors. They also noticed that female mice were more likely to overeat when their hormones were imbalanced, which could explain why more women engage in comfort eating.
Age could be another factor. Lack of appetite in old age is a common phenomenon. As we get older, we tend to suffer more from apathy, cognitive impairment, sleep disorders and physical illnesses — factors that interfere with our stress response. As such, it’s likely that aging processes may also modify the impact of ghrelin on our eating behaviors.
Leptin is another hormone involved in appetite control, promoting feelings of fullness and satiety. According to the Nutrients (opens in new tab) journal, leptin levels decrease following acute stress, with normal-weight individuals and women displaying more severe fluctuations.
Another factor that links stress and appetite are orexins, compounds released by the brain in response to stressors. According to the Frontiers in Neuroendocrinology (opens in new tab) journal, they have also been shown to modify eating behaviors.
Why do some people eat more when they're stressed?
“Some people eat more when stressed as a coping mechanism to help reduce their stress, often referred to as emotional eating,” says Rahaf Al Bochi, registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics (opens in new tab). “When the body is under stress, it releases the stress hormone cortisol which can increase appetite. Many tend to crave ‘comfort foods’ which tend to be high in fat and/or sugar.”
Al Bochi is the owner of a nutrition consulting practice where she provides holistic counseling with a focus on diabetes and women's prenatal health. Al Bochi received the 2020 Georgia Academy of Nutrition and Dietetics Outstanding Service to the Media Award. She is a member of the Academy's Nutrition Entrepreneurs dietetic practice group and is a graduate of Ryerson University.
Ashley Bannister, registered dietitian nutritionist and health coach at Noom (opens in new tab), also adds: “Foods high in fat and/or sugar have been shown to dampen the body’s stress response. As a result, you may find it difficult to overcome the urge to eat due to stress since there are physiological mechanisms that predispose us to stress eating. Lastly, comfort foods can activate the reward system in the brain, making it even more difficult to manage comfort eating.”
Ashley Bannister is a health coach at Noom. She holds a Bachelor of Science in Biology from Towson University and a Master's degree in Human Nutrition and Dietetics from Drexel University.
According to the Annual Review of Psychology (opens in new tab) journal, stress also interferes with our executive function and self-regulation, which in turn can alter our decision process. It can also lead to a decrease in physical activity and sleep, two important factors for the regulation of appetite hormones.
Scientists also propose a Reward Based Stress Eating model to help explain this phenomenon, as stated in the Physiology & Behavior (opens in new tab) journal. It places the emphasis on the role of cortisol and brain reward circuitry, as well as various compounds released in response to stress. For example, both stress and palatable food can stimulate the release of opioids in the body. One of the most well-known opioids are endorphins, the ‘feel-good’ chemicals which have the ability to lower the pain levels and make us feel more relaxed. Repeated stimulation of these reward pathways can lower our body’s ‘pleasure threshold’ and promote the compulsive nature of overeating.
- Related: What is binge eating disorder?
Why do some people eat less when they’re stressed?
Many experts agree that the phenomenon of appetite loss when stressed depends mostly on our physiology, and this effect is often temporary.
“Initially, under acute stress, you may find that your appetite actually decreases,” says Ashley Bannister. “This is a result of a hormonal response related to stress. Epinephrine becomes elevated in acute stress, which triggers the fight or flight response in the body. This results in a state that temporarily decreases appetite. As stress continues, cortisol levels rise, which leads to increased appetite and this can lead to stress eating.”
However, evidence is growing that appetite loss may also be linked to mood disorders. According to a study published in the Comprehensive Psychoneuroendocrinology (opens in new tab) journal, people suffering from depression reporting appetite loss may have higher cortisol compared to controls, and marginally higher cortisol than those with depression reporting an increase in appetite. However, more research is needed to fully understand why that is the case.
How to relieve stress without under- or overeating
Stress is the root cause of comfort eating, and relieving it is the first step to improving your relationship with food. But as we all know, it may be easier said than done. So what do experts recommend?
“Identify coping mechanisms to help relieve the stress by creating a stress reducing ‘toolbox’ that you can use in times of stress,” advises Rahaf Al Bochi. “Examples include going for a walk, talking with a friend, taking a bath, deep breathing, listening to music, or meditation.”
These may sound like simple solutions, but evidence backs them up. According to the Appetite (opens in new tab) journal, studies have shown that taking the time and effort to relax on a regular basis may effectively reduce stress eating.
“Overall, what works for you will depend on you as a unique individual, and it may take some trial and error to figure it out,” points out Bannister. “Understanding the ‘why’ behind stress eating can help play a role in altering the behavior. We can’t eliminate stress from our lives, and we can’t eliminate the body’s stress response, but what we can do is find ways to cope with stress without turning to food or altering our intake.”
Bannister recommends having a strong social support system in place and maintaining connections with those individuals, giving you someone to turn to in response to stressful situations. Engaging in activities that may serve as a helpful distraction can also help to reduce stress.
Finally, mindful eating can help you to identify your triggers and stay level headed when making a choice.
“You might ask yourself, ‘Am I truly hungry?’, ‘How will I feel after eating?’, ‘Is there something else I could be doing that might help me cope with stress?’” says Bannister.
This article is for informational purposes only and is not meant to offer medical advice.