Your body’s stress response
Your fight-or-flight response (aka your body’s automatic stress response) starts in your brain, specifically in the amygdala and hypothalamus. The amygdala is your brain’s vigilant lookout — when it perceives danger in the environment, it notifies your hypothalamus to activate your sympathetic nervous system. That means telling the adrenal glands (endocrine glands located above the kidneys) to secrete hormones that prepare your body to take action against whatever perceived danger is nearby.
Epinephrine and cortisol (aka the stress hormone) are two key hormones to understand here. Epinephrine, which is released first, induces physiological changes including a quickened heart rate and increased blood pressure. Cortisol subsequently triggers bodily changes to give you extra energy, including an increased appetite and storage of unused nutrients as fat. Your cortisol level falls once the perceived danger goes away.
Elevated cortisol levels and weight
Cortisol is one of many factors that influence eating habits and food choices; high levels of the hormone can leave you reaching for high-fat and energy-dense food. Chronic stress, which affects how cortisol functions, puts people at greater risk of developing health complications, including obesity, cardiovascular disease and impaired immunity.
Many studies link high cortisol levels to chronic stress, weight gain and obesity. A 2017 study found that people were more likely to gain weight if they had higher baseline levels of cortisol, insulin and stress. Those with high cortisol levels were more likely to partake in emotional or stress-induced eating. Why? Because high levels of cortisol and fasting ghrelin, an appetite-stimulating hormone, can trigger cravings for food, especially sweets and carbohydrates.
High levels of cortisol and insulin, a hormone that manages blood glucose (sugar) levels, can lead to fat accumulation and insulin resistance — both of which can influence metabolism and insulin functioning, further contributing to weight gain.
The weight-gain cycle: unhealthy habits stemming from stress
We all respond to stress differently, but unhealthy lifestyle habits commonly emerge when stress levels are high. Here are two stress-related habits that can contribute to weight gain:
Emotional eating: Also known as comfort eating or stress-induced eating, emotional eating is when you eat as a response to negative emotions. Emotional eating stimulates the reward center in your brain, making you think that eating will reduce or eliminate negative feelings.
Compared to non-emotional eaters, emotional eaters tend to eat higher-fat foods and snack more often. And, according to a 2023 review paper, emotional eating is linked to excessive alcohol intake. The same paper also found that emotional eating was more common in people with obesity, versus those of normal weight.
Poor sleep: People averaging less than six hours of sleep a night tend to have a higher body mass index (BMI) on average, according to a 2022 review paper about sleep and weight loss. Sleep loss leads to higher caloric intake in two ways:
- Less sleep means more hours in the day for snacking.
- Increased ghrelin levels further stimulate your appetite.
Sleep-related disorders, such as sleep apnea, can further contribute to poor sleep and weight gain.
Managing stress and weight gain
Management strategies for stress are intended to bring down stress levels by inducing relaxation and thwarting a fight-or-flight response. Here are some stress-management strategies that can also help with weight loss:
- Exercise: Exercise blocks the release of cortisol. It can also help curb food cravings, especially for sugary snacks.
- Deep breathing: Deep or diaphragmatic breathing involves slowly expanding your lungs into your diaphragm and controlling your respiratory rate as you breathe in and out through your nose. This interrupts your fight-or-flight response and may result in lower cortisol levels.
- Mindfulness: Meditation can quiet your mind and make you less reactive to stress. Daily use of mindfulness apps for short, guided meditations have been shown to improve overall well-being.
- Sleep: A better sleep environment — no tech use in bed, proper room temperature, limited noise and light — can improve sleep quality, which can help reduce stress.
Before developing a plan to reduce stress or lose weight or both, it’s smart to consult a healthcare provider. They can advise you on the optimal ways to tackle both issues and share tips to implement strategies into your daily life.