It has long been theorized that an association exists between long-term stress and obesity. Chronic stress can lead to “comfort eating,” which often involves the overeating of foods that are high in fat, sugar, and calories, which, in turn, can lead to weight gain.
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The effects of stress on weight
While short-term stress can cause a person to lose their appetite, chronic stress can have the opposite effect.
Stress, in the short term, causes the brain to produce an appetite-suppressing hormone called corticotrophin-releasing hormone. During times of stress, signals are also sent to the adrenal glands that trigger their production of adrenalin, which temporarily suppresses any urge to eat as part of the fight-or-flight response.
Ongoing stress, on the other hand, causes the release of a hormone called cortisol. This hormone increases a person’s appetite and, if the stress does not pass, cortisol and appetite levels remain increased.
Supporting scientific studies
In one study conducted at University College London (UCL), researchers looked at whether there was an association between levels of cortisol present in the hair, as well as the body mass index (BMI) and waist circumference of their test subjects.
Data was recorded over four years, with more than 2,500 men and women participating in this study. The 2-cm pieces of hair that were analyzed in this study represented about 2 months' worth of growth, with the cortisol levels that had continued to increase built up over the course of the study.
The leader of this study, Sarah Jackson, and her team found that higher levels of cortisol in the hair were associated with greater waist circumferences and higher BMIs. People who had a BMI of 30 or more and therefore classified as obese had especially high hair cortisol levels. Furthermore, retrospective analyses over the 4-year period showed a positive association between hair cortisol levels and the persistence of obesity over time.
In a British study, researchers found that people who had high cortisol levels in response to stress had a greater tendency to eat snacks when experiencing day-to-day problems as compared to people who had low cortisol levels in response to stress.
In another study from the Hebrew University of Jerusalem, researchers looked at the molecular mechanisms that may link anxiety and metabolism. Specifically, these researchers looked at the link between the expression of a certain type of microRNA and processes related to metabolic syndrome.
Hermona Soreq and her team of researchers had already performed studies showing increased expression of microRNA inflammation regulators within the brain and gut in response to stress and anxiety. However, the researchers wanted to further explore any influence that this had on obesity.
To this end, Soreq's team found that microRNA expression as a result of anxiety could increase the effects of processes related to metabolic syndrome. They also found that the microRNA expression levels varied between different cells and tissues, depending on whether subjects had been exposed to stress.
Many animal studies have also suggested that stress influences food preferences, with foods rich in fat and sugar being preferred when subjects become either physically or emotionally stressed. These foods appear to inhibit brain activity that is involved in the processing of stress and anxiety, which has the effect of counteracting these emotions.
Aside from overeating, stress can also lead to sleep problems, decreased motivation to exercise, and increased alcohol consumption, all factors that increase the likelihood of weight gain.
The unhealthy connection between stress and weight gain
The main step a person can take if they find that stress has increased their hunger levels and their weight is to eliminate foods in the diet that are high in fat and sugar.
Some other recommendations are described below:
- Exercise: When a person exercises vigorously, cortisol level rises, although only in the short term. Gentle exercise, on the other hand, tends to lower cortisol for longer periods of time.
- Meditation: Many studies have demonstrated that meditation can decrease stress. This practice may also motivate people to be more alert about which foods they choose to buy and consume.
- Emotional support: Being supported by friends and family appears to be beneficial in counteracting stress. Research has also shown that individuals working in typically stressful environments are significantly less likely to have mental health problems if they feel supported by those around them.