Obesity and emotional stress

“If a person is subjected to constant stress over a period of a few months, this increases their risk for obesity” writes Health.com, citing researchers from University College London – https://www.health.com/"

Under conditions of stress the organism is forced to produce large amounts of the hormone cortisol. Under normal conditions, its role is to prepare the organism for a “fight-or-flight” response. In order to do that, it acts on the cardio-vascular system and increases cardiac activity and the blood pressure, and redistributes the blood by directing it to those organs and systems, which are most important for the stress response. One of its main functions is to provide energy by supplying cells with glucose, which is an easily accessible and quick energy source. Cortisol does this by regulating the production of glucose from glucogenic amino acids, the building blocks of muscle proteins. This is facilitated by the hormone adrenaline, which is also elevated during stress. Adrenaline breaks down the liver glycogen to glucose, which is then used as an energy source. The adaptive reaction to stress is necessary for survival and for overcoming life’s difficulties. However, long-term stress results in chronically elevated cortisol levels. This then leads to the exhaustion of the glucose stores, which provides a signal to the organism to quickly replenish them. Cortisol increases the appetite and the need for the immediate intake of large amounts of food, which is primarily sweet and high in fats. On the other hand, it facilitates the accumulation of lipids in the cells, which leads to obesity, reduced muscle mass and impaired memory functions.

Scientists from University College London used human hair in order to measure the levels of the stress hormone cortisol in the human body. Hair samples give a more accurate reading of the long-term hormone levels compared to other sample types, according to the authors (https://www.globality-health.com/). For the purpose of the study, the researchers collected hair samples from 2500 men and women over a period of four years, and then analyzed them for cortisol. In addition, they recorded the body weight of the participants, their body mass index (BMI) and their waist circumference over time. The researchers observed a clear association between stress levels and obesity.

People who had higher cortisol levels also had an increased weight!

People who could be classified as overweight according to their BMI (equal to or above 30) or waist circumference (over 102 cm in men and over 88 cm in women) had very high hair cortisol concentrations. This finding is in accordance with previous studies, which show that high levels of stress can lead to the development of unhealthy habits, such as sleep deprivation and the consumption of fatty foods and sweets.

Doctors Susan Fried and Sarah Jackson have shown through their work that cortisol levels affect the metabolism and the storage of fat in the organism, which can result in weight gain if there are no behavioral changes. “The association between the levels of cortisol and the waist circumference is particularly important because the accumulation of fat in the body’s mid-section is a known risk factor for cardio-vascular diseases, diabetes and early mortality”, says senior investigator Dr. Sarah Jackson, a psychologist in the Department of Behavioural Science and Health at University College London (Jackson, S).

Dr. Susan Fried, a Professor of Medicine at the ICAHN School of Medicine, says that being overweight can itself cause increased levels of stress. “The study investigated the levels of cortisol in the participants over a period of a few months, but their obesity had most likely started to develop many years earlier.”, says Fried. “This means that the high levels of hair cortisol may reflect the social and biological stress associated with being overweight.”, she says. For example, medical conditions associated with being overweight (such as high blood pressure and arthritis) can cause stress over time. Dr. Jackson agrees with the hypothesis that it is worth investigating how stress can influence weight gain. There are also purely psychological aspects to stress. When people are under constant stress they feel exhausted, melancholic, unsatisfied with life, unhappy, angry and lonely. Food can be an accessible and quick source of happiness and self-esteem. Food can shift one’s attention towards the transient sense of pleasure and happiness, instead of towards finding solutions for the problems. Overeating becomes a universal way to escape real life, to escape the stress and to create the illusion of inner wellbeing by saving us from our loneliness and sad thoughts. 

Chronic stress insidiously pushes people towards obesity in other ways as well. It increases the synthesis of Neuropeptide Y in the brain. Apart from being one of the strongest stimulants of the appetite, it also stimulates the development of additional blood vessels in the adipose tissue and increases the number and size of the fat cells (also called adipocytes). In this way it creates the conditions for the increased accumulation of fat in the human body. This leads to additional stress, which is multiplied by the numerous diets that everyone that is overweight has surely tried. Data from a new study has shown that stress disrupts the circadian rhythm as well and in this way can also lead to weight gain. Associate Professor Dr. Mary Teruel from the Weill Cornell Medical College in the USA, who was a part of the study, explains that there are many internal and external factors, which prevent the maintenance of a healthy metabolism. During the study, pellets releasing glucocorticoids were implanted in experimental mice for three weeks in order to prevent the physiological glucocorticoid level oscillations. Glucocorticoids are steroid hormones associated with stress. The main idea of the study was to recapitulate the consequences of chronic stress or Cushing Syndrome, both of which are associated with increased levels of cortisol. The results showed increased insulin production. To the surprise of the researchers, the hormonal dysregulation led to decreased blood sugar levels. In addition, disruptions in the circadian glucocorticoid rhythm prevented the accumulation of fatty acids in the bloodstream and the liver. When the normal circadian glucocorticoid rhythm was restored, the accumulation of fat decreased and the hyperinsulinemia was reversed. Dr. Teruel explains that the results from this study show that chronic stress can make weight gain more likely, even if a healthy low-fat diet is being observed. Researchers now understand that defects in the activity of “clock genes”, which regulate circadian rhythms, can lead to changes in the differentiation of fat, immune, skin and muscle cells.

In order to prevent the epidemic of obesity, diabetes and high blood pressure, people should change their sedentary lifestyle to a more physically active way of life. In this context, taking part in physical activities such as aerobic exercises is a popular choice for obese people. Furthermore, overweight and obese people should improve their health and physical activity while they are young, which is important and valuable in our modern way of life. Despite this, metabolic demands can be increased significantly during and after exercise. It is obvious that such increases result in an excellent caloric expenditure, which mainly depends on the type of training.

References

https://www.health.com/

https://www.globality-health.com/

Jackson, A. S., & Pollock, M. L. (1978). Generalized equations for predicting body density of men. British Journal of Nutrition, 40, 497-504.

Abell, J. et al. Assessing cortisol from hair samples in a large observational cohort: The Whitehall II study. Psychoneuroendocrinology 2016 Nov:73:148-156. doi: 10.1016/j.psyneuen.2016.07.214.

Tholen, S. et al. Flattening of circadian glucocorticoid oscillations drives acute hyperinsulinemia and adipocyte hypertrophy. Cell Rep 2022 Jun 28;39(13):111018. doi: 10.1016/j.celrep.2022.111018.

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