Americans today are more stressed than ever. We face stress at work, home, in our relationships and even from lack of sleep. Unfortunately, we are finding that chronic stress is causing a serious impact on our lives and our health. We now know that chronic stress can lead to:
High blood pressure, diabetes, obesity, and metabolic syndrome
Anxiety & Depression
There is a growing body of literature that is looking at just how our bodies respond to stress, and how we can treat the deleterious effects of stress. But what is stress exactly? And why, when you are cramming for your final exam (or like me, up against a deadline to get an article finished), are you polishing off your last Twix and not a carrot?
What is stress?
Stress is any real or perceived threat to homeostasis (or our steady state of calm). This can be emotional stress, alteration in your sleep patterns, or even fear of physical harm. Our body has two systems designed to control how our body responds: the sympathetic nervous system (fight or flight system) and parasympathetic nervous system (rest and digest system). When we are initially stressed (i.e., running from a bear), our bodies activate the sympathetic nervous system. This, in turn, switches on the Hypothalamic Pituitary Adrenal Axis, a pathway in our body where our brain tells different parts of our body how to respond to stress. One of the main components of this system is cortisol. Cortisol is a steroid hormone that, in addition to many other actions, modulates glucose metabolism. Through a variety of pathways, high cortisol levels causes adipose tissue (fat cells which store energy) to break down in order to release their energy. The energy released from these cells can be shunted to the tissues that need them most. Cortisol has been found to have several different functions:
Manages how your body uses / stores fats and proteins in times of stress
Adjusts blood pressure and glucose levels
Controls your sleep / wake cycle
Influences immune system
Affects learning and memory in times of stress
In a healthy response to stress, the body will quickly raise cortisol levels in an effort to handle the stress. Once the stressor is gone, the parasympathetic system kicks in (rest and digest system), and cortisol levels fall. However, when a person is burdened with continued stressors, the cortisol levels are unable to fall. This persistent state of high cortisol production can lead to various metabolic and psychiatric disorders.
How do high cortisol levels affect your weight?
You may think, in short periods of stress, fat is broken down to produce energy. Isn’t that a good thing? Unfortunately, you can certainly have too much of a good thing! Obesity has certainly been linked to persistently high levels of cortisol in several ways. One theory is that persistently high levels of cortisol, in response to chronic stress, actually causes a blunted response or desensitization. This, in turn, inhibits fat cell break down (lipolysis) and leads to insulin resistance.1 This is perhaps why stress, cortisol level and diabetes are significantly linked.
High cortisol levels also interact with a variety of signaling pathways involved with appetite. Leptin, the “satiety hormone,” is released from fat cells to help control weight long-term. It helps to inhibit hunger.2 When the body is functioning properly, leptin levels will rise to lower your appetite. However, when chronically stressed (in the setting of chronically high cortisol levels), leptin receptors can be desensitized and can actually increase hunger and eating. 3 When a patient is obese, this can be magnified. Because as the individual keeps eating, the fat cells produce more leptin to signal the need for satiety, leading to even higher levels of leptin.2
Ghrelin is another appetite hormone that has received more notoriety recently. Ghrelin is a hormone secreted in the stomach and works to increase food intake. In bariatric surgery, we have found that ghrelin levels are reduced in the short term. This can add to the success of surgeries like the gastric bypass and sleeve gastrectomy. However, studies have looked at the effects of cortisol and sleep deprivation (a chronic stressor) and ghrelin. Research has shown that in periods of sleep deprivation, there is an increase in nocturnal ghrelin, leading to increase in appetite. This may be why when you can’t sleep, you have the urge to reach for comfort foods, such as sweets.3
Finally, there is the behavioral component of eating and stress. Stressors work on three parts of the brain:
Prefrontal cortex – involved with “Thinking” and mindful regulation of food intake.
Hippocampus – involved with “Emotions” and the wanting, pleasurable habitual regulation of food intake
Hypothalamus – involved with “Energy balance” and body’s homeostatic regulation of food
I think of the prefrontal cortex and hippocampus as our higher brain and hypothalamus more of our primitive brain. In periods of chronic stress, cortisol is released and maintained at a high level, and this, in turn, increases our motivations for food intake and obesity. Our prefrontal cortex and hippocampus “take over” the hypothalamus in times of chronic stress. Through pleasurable eating, the body is trying to reduce the activity of the stress-response network. This dysregulated pathway reinforces the bad feeding habit. As much as our genetics and hormones play a role in our eating habits and weight, patterns of poor eating can be learned and reinforced over time. 4
In summary, the hormones that are supposed to control appetite and hunger are dysregulated. This causes the body to try to restore a normal balance through bad habits. This is why so many patients rely on food during periods of stress.
Cortisol and Anxiety / Depression
There have been several studies that show there is a positive association between depression and obesity. Obesity has been shown to cause depression and vice versa. In periods of chronic stress, the HPA is activated, cortisol is high, ultimately resulting in obesity. Additionally, studies have found that early in life if there are stressors, such as abuse, the HPA is activated and dysregulated. This leads to higher risk for anxiety, depression and addiction.5
So what can we do?
The evidence is clear that periods of high stress, through various pathways, can lead to obesity and psychological disorders such as depression and anxiety. By understanding that stress is a very real thing, and has very real consequences is the first step. For patients with depression and anxiety, it is important that they receive adequate medical and behavioral care. Since these diseases are bidirectional with obesity, one can have a significant impact on another. For instance, it is not uncommon for me to have a patient present two years out from surgery with some weight gain. After meeting with them, I often find that a major life event (such as birth, death, divorce, loss of job) has occurred. While I could just give them an appetite suppressant and cross my fingers, this is just putting a band-aid on a problem. A more comprehensive approach would be to address the anxiety / depression underlying the weight regain. In the same way, if a patient presents with issues with insomnia, it is important to tease out why they can’t sleep. Do they have untreated sleep apnea? Are they stressed or depressed? Do they work nights and have an altered sleep schedule? By addressing the underlying cause of the sleep deprivation, using a sleeping aid and enforcing good sleep hygiene, a patient can lose up to 10% of their excess body weight. So what if you aren’t depressed and sleep well at night, but you just have a crazy, hectic lifestyle. If that is the case, then if you want to lose weight, you MUST make time to take care of yourself and de-stress. I’ve always said everyone needs to know a good plumber, good lawyer and good therapist! Therapy is a wonderful way to change maladaptive behaviors that contribute to our stress. Exercise is another great way to “work out” your stress. Exercise has also been shown to release endorphins to help lower our cortisol levels.
As I complete this article, I feel better knowing why I reach for the snack foods that I do when I’m stressed. This, in turn, helps me to be more mindful about the choices I make. For you and all my patients, my hope is that you can find a better, more healthy and mindful way to control your stress….your waistline will thank you for it!
References HYPERLINK “mailto:email@example.com” \o “firstname.lastname@example.org” INCLUDEPICTURE “https://link.springer.com/springerlink-static/images/svg/email.svg” \* MERGEFORMATINET
Scott, Karen, Susan Melhorn, and Randall Sakai. (March 2012). Effects of Chronic Social Stress on Obesity. Current Obesity Reports, 1(1):16–25.
HYPERLINK “https://www.ncbi.nlm.nih.gov/pubmed/?term=Bose%20M%5BAuthor%5D&cauthor=true&cauthor_uid=19584720” Mousumi Bose, HYPERLINK “https://www.ncbi.nlm.nih.gov/pubmed/?term=Oliv%26%23x000e1%3Bn%20B%5BAuthor%5D&cauthor=true&cauthor_uid=19584720” Blanca Oliván, and HYPERLINK “https://www.ncbi.nlm.nih.gov/pubmed/?term=Laferr%26%23x000e8%3Bre%20B%5BAuthor%5D&cauthor=true&cauthor_uid=19584720” Blandine Laferrère. (Oct 2009). Stress and obesity: the role of the hypothalamic–pituitary–adrenal axis in metabolic disease. Current Opinion in Endocrinology, Diabetes and Obesity. 16(5):340–346.
Dallman, MF. (Nov 2009). Stress-induced obesity and the emotional nervous system. HYPERLINK “https://www.ncbi.nlm.nih.gov/pubmed/19926299” \o “Trends in endocrinology and metabolism: TEM.” Trends Endocrinol Metab. 2010 Mar;21(3):159-65.
C.R. Elder, CM Gullion, KL Funk, LL DeVar, NM Lindberg, and VJ Stevens. (2012). Impact of sleep, screen time, depression and stress on weight change in the intensive weight loss phase of the LIFE study. International Journal of Obesity, 36:86–92.