Nutrition and Stress

Why do we eat more when we’re stressed? And why does it tend to be cookies rather than carrots? Lucky for you, you can now blame science; stress, appetite, and nutritional health are closely intertwined. 

One of the main ways in which stress impacts nutrition is through a steroid hormone called cortisol. Cortisol is a key player in processes such as blood pressure regulation, memory formation, and blood sugar control. Its release typically follows a diurnal rhythm, meaning that levels are highest in the morning and lowest at night. When you experience stress, the adrenal glands secrete more cortisol in order to induce physiological changes to help you deal with the threat. While this can be beneficial when the stressor requires an immediate physical response (e.g. when someone is chasing you), it’s less helpful when it’s psychological and persistent (e.g. when you have money troubles). Chronically elevated cortisol levels can affect appetite control, body weight, and overall health.

Hunger, food selection, and body weight

Persistent stress may make it harder for you to stay away from the vending machine. Chronically elevated cortisol levels can stimulate your appetite and trigger cravings for calorie-rich foods through interactions with hunger hormones and the reward system. Higher cortisol levels are also associated with adipose (fat) tissue expansion and abdominal obesity. 

Digestion

Cortisol favors the sympathetic (fight-or-flight) nervous system at the expense of the parasympathetic (rest) nervous system. This hinders digestion, which functions optimally when the body is at rest. Stress may therefore lead to indigestion, exacerbate gastrointestinal issues such as irritable bowel syndrome, and potentially even alter the composition of the gut microbiome.

Blood sugar

One of the primary purposes of cortisol in the fight or flight response is to raise blood sugar (glucose) levels to give you immediate access to usable energy. It does this by making glucose via protein breakdown in the liver and counteracting insulin, thus limiting the amount of sugar that is taken up from the bloodstream. When cortisol levels remain chronically high, this can lead to insulin resistance and increase your risk for diabetes.

Blood pressure

Ever heard the phrase “Calm down, you’ll have a heart attack”? Cortisol raises heart rate and blood pressure to quickly push oxygenated blood to the muscles and viral organs. Again, this is good if you’re trying to escape an immediate threat, but bad for long-term cardiovascular health. High blood pressure, or hypertension, can damage your blood vessels and increase your risk of heart attack and stroke.

Inflammation

Cortisol acts as an anti-inflammatory agent and suppresses the immune system; when it is consistently elevated, this can increase susceptibility to viruses and bacteria. Chronic low-grade inflammation (as is seen in obesity) may further propagate the effects of the stress response, as more inflammation means that more cortisol is released to counteract it.

So now that I’ve stressed you out even more by telling you about all of the ways that stress contributes to poor health, what can you do about it? Choosing complex carbohydrates and minimizing added sugar in your diet will mitigate blood sugar spikes and crashes. Following an anti-inflammatory diet pattern such as the Mediterranean diet (which focuses on fresh produce, lean protein, and healthy fats) will reduce the need for extra cortisol production to fight inflammation. Including foods rich in prebiotics and probiotics in your diet will support a healthy microbiome, which may help directly modulate the stress response via the gut-brain axis. And don’t forget about drinking water — adequate hydration is vital for immunity, hunger regulation, and blood pressure control.

It’s not only what you eat — it’s how you eat. I may sound like a broken record here, but I will forever be a proponent of mindfulness practices such as mindful eating. Studies have shown that mindfulness training can have a direct beneficial impact on some of the physiological indicators mentioned above such as blood pressure, inflammation, and the immune response. Applying mindfulness to your food practices specifically can help you manage your cravings and eat less.

Stress, food cravings, body weight, and nutritional health are interconnected through a series of complex feedback loops. This is actually good news, because it means that improving any part of the cycle can have a positive impact on the others. Taking small steps to improve your diet and mindfulness skills can go a long way in contributing to better health outcomes overall.

References

Chao, Ariana M., et al. “Stress, Cortisol, and Other Appetite-Related Hormones: Prospective Prediction of 6-Month Changes in Food Cravings and Weight.” Obesity, vol. 25, no. 4, Apr. 2017, pp. 713–720., doi:10.1002/oby.21790.

Coutinho, Agnes E., and Karen E. Chapman. “The Anti-Inflammatory and Immunosuppressive Effects of Glucocorticoids, Recent Developments and Mechanistic Insights.” Molecular and Cellular Endocrinology, vol. 335, no. 1, Mar. 2011, pp. 2–13., doi:10.1016/j.mce.2010.04.005.

Geer, Eliza B., et al. “Mechanisms of Glucocorticoid-Induced Insulin Resistance.” Endocrinology and Metabolism Clinics of North America, vol. 43, no. 1, Mar. 2014, pp. 75–102., doi:10.1016/j.ecl.2013.10.005.

Schnepper, Rebekka, et al. “Fight, Flight, – Or Grab a Bite! Trait Emotional and Restrained Eating Style Predicts Food Cue Responding Under Negative Emotions.” Frontiers in Behavioral Neuroscience, vol. 14, June 2020, doi:10.3389/fnbeh.2020.00091.Whitworth, Judith A, et al. “Cardiovascular Consequences of Cortisol Excess.” Vascular Health and Risk Management, vol. 1, no. 4, Dec. 2005, pp. 291–299., doi:10.2147/vhrm.2005.1.4.291.