Homeostasis, Exercise, and COVID-19 Isolation


The Value of Exercise

A recent post explored human needs during COVID-19 isolation. The success of social isolation policies will depend on minimizing long-term depreciation of mental health. In this post, I explain the benefits of developing a system of daily exercise to bolster well-being.

Exercise is an under-utilised resource that is freely available to almost everyone, which can bring profound benefits if applied systematically. The impact of exercise is one of the most powerful examples of regulation created by homeostasis. Regular physical activity not only has obvious physical benefits but significant psychological benefits also. During COVID-19 isolation, exercise offers the capability to reset body and mind to a more optimum state of equilibrium.

Hawley et al. (2014) state: “Exercise represents a major challenge to whole-body homeostasis, and in an attempt to meet this challenge, myriad acute and adaptive responses take place at the cellular and systemic levels that function to minimize these widespread disruptions.”


The Physiological Responses to Voluntary, Dynamic Exercise. Multiple organ systems are affected by exercise, initiating diverse homeostatic responses. Reproduced from ‘Integrative Biology of Exercise’ by Hawley et al. (2014).

Note of caution

Apart from its general ability to challenge homeostasis to reset the body’s biological equilibrium, exercise has a role in two domains of well-being:

(1) the immune system is strengthened through regular physical activity (Campbell and Turner, 2018; Simpson et al., 2020)

(2) psychological well-being is enhanced (Mandolesi et al., 2018).

However, exercise is no panacea.

Exercise must be applied with caution especially by people with chronic conditions. If a person has a heart condition, strenuous physical exercise may put them at risk (Keteyian et al., 2016).

In some chronic conditions such as ME/CFS, exercise tends to make many patients feel much worse (Geraghty et al., 2019).

However, if used safely and appropriately, the majority of people can quickly feel physical and mental benefits from regular exercise.

Physiological Mechanisms

Some significant effects of physical activity can be explained by physiological mechanisms (Lopresti et al., 2013). Exercise within the context of psychological health promotion has also been an active research area (Chekroud et al., 2018; Curioni and Lourenco, 2005; Mikkelsen et al., 2017; Tiggemann and Zaccardo, 2018). Some researchers have focused on neurophysiological mechanisms, which aim to identify the positive outcomes of the relationship between exercise and mental health (Eyre and Baune, 2012). Exercise is understood as a relationship between intensity and frequency, and positive outcomes are mostly based on which exercise protocol will determine a better neurophysiological response (Lopresti et al., 2013). Exercise is recognized as a mediator of primary monoamine neurotransmitters, namely, serotonin, noradrenaline and dopamine. These three neurotransmitters receive reciprocal regulation, while exercise intensity modulates the stimulation of monoamine system (Lin and Kuo, 2013). However, it is also important to recognize the affective responses of physical activities and psychological variables are likely to mediate the relationship between exercise and mental health (Rodrigues et al., 2019). There is a sound empirical basis for an integrated account of the emotional effects of exercise. A recent study with a representative US sample of 1.2 million individuals linked exercise to mental health and exercising was associated with reduced self-reported mental health burden. Furthermore, motivation and mindfulness-based techniques act as mediators for these relationships, which seem to account for the strongest effect of the exercise on fewer days of poor mental health (Chekroud et al., 2018).

Joy and Happiness


In the context of social isolation, exercise can be an inherently rewarding activity that contributes joy, happiness and satisfaction (Ryan and Deci, 2017; Standage and Ryan, 2012). The positive outcomes also appear as a function of affective consequences of exercise or anticipation of its affective response – the hedonic principle of the law of effect (Marks, 2018). In general, the expected pleasure versus displeasure is a determining principle of the motivation to repeat behaviour (Kwasnicka et al., 2016; Williams, 2008).

Isolation and quarantine are a disagreeable experience, which may lead to sadness and even impose dramatic mental illness for those who undergo it (Brooks et al., 2020). In this context, a daily exercise routine can be crucial to modulating pleasurable situations at some point during the day. People can feel more deeply satisfied through the experience of choice and volition, reinforce their sense of autonomy and competence, and renew a sense of joy (Lubans et al., 2017; Ryan and Deci, 2017; Standage and Ryan, 2012).

The benefits of exercise depend on the degree of internalization of the behaviour. In our daily lives, exercises are normally performed in order to achieve goals, such as social aesthetic standards (Sperandei et al., 2016). These goals are separable from the purpose of the exercise (a person may not enjoy exercising, but will do it to obtain a result); and therefore, people are generally not ‘authentic’. The lack of authenticity represents a person doing an activity for contingent reward or punishment, feeling tense and pressured, lacking intentionality and being oriented to avoid guilt, angst and social judgement or to protect contingent self-worth. Contrarily, people are authentic when exercise choice is aligned with personal goals, interest and is assimilated with the individual’s characteristics, ability and identity (Deci and Flaste, 1995). Identity is associated with ongoing positive experiences attendant on the behaviour (Kwasnicka et al., 2016), such as exercising at home.

Notably, the COVID-19 pandemic causes fear and the lockdown imposes limits on people’s movement (Brooks et al., 2020; Xiang et al., 2020).

The rationale for the positive side of exercising at home is that exercise can be experienced without any strong social pressure, having a totally internal source of inspiration. The behaviour might be accompanied by higher self-esteem and lower psychological ill-being, since we are free to choose the:

  • types of exercise
  • schedule
  • frequency
  • intensity

The fulfilment of basic psychological needs appear within this context.

Authenticity and Self-Compassion


Another helpful process is that of self-compassion – the ability to treat oneself with the same concern and support in distressing situations; it is related to self-kindness, common humanity and mindfulness. In fact, it is associated with self-regulation when performing health-promotion behaviours (Holden et al., 2020; Semenchuk et al., 2018). Exercising at home, in a crisis situation, can be performed without self-criticism, which could hinder the process by increasing pressure and self-judgement, which in turn may provide adaptive coping, problem-solving and psychological well-being.

Research has provided empirical evidence on the positive relationship between self-compassion and exercise in providing exercise maintenance and enhancing positive emotions (Holden et al., 2020; Semenchuk et al., 2018).

Mastery and Self-control

Exercising at home can increase the individual’s sense of control. Research suggests that self-mastery is a crucial criterion for promoting positive effects on psychological outcomes (Mikkelsen et al., 2017; Ryan and Deci, 2017). In the face of this pandemic, we have seen many examples across the world showing that exercise can create a social arena in which individuals learn social skills and build social networks by adhering to exercise challenges, exercising in condominiums and encouraging others. These virtual social connections enhance feelings of autonomy and being fully alive. When autonomous forms of regulation guide behaviour, positive affective responses are expected (Ryan and Deci, 2017; Standage and Ryan, 2012). One example is the QuaranTrain launched at HAN University of Applied Sciences in the Netherlands, an online fitness programme promoting evidence-based information on exercise and resources to stay active during COVID-19 pandemic through blogs and videos (HAN University of Applied Sciences, 2020). They provide daily online support, according to World Health Organization advice on physical activity. Users post their workouts routines in social media using the trending hashtags #quarantrain and #quarantraining, with more than 5000 posts worldwide.

Self-efficacy and Self-esteem

Being engaged in exercise may result in higher levels of self-efficacy (Bandura, 1997) which can have the knock-on effect of improving one’s ability to carry out other activities (Mikkelsen et al., 2017). The relationship between changes in the ability to perform activities successfully and increased self-efficacy is fundamental, considering the observed association between depression and low self-efficacy (White et al., 2009). In the context of social isolation, physical activity may be one key to enhancing people’s feeling of competence. In addition, achievement of internal goals and satisfaction has been related to greater psychological wellness (Ryan and Deci, 2017; Standage and Ryan, 2012). This hypothesis has been confirmed by an experimental protocol in which mindfulness self-efficacy appeared to mediate the indirect effects of exercise on mental health and perceived stress (Goldstein et al., 2018), reinforcing the positive account of emotion for a better quality of life (Joseph et al., 2014).


Mikkelsen et al. (2017) observed that exercise influences self-esteem through self-efficacy or mastery, and mood, distracting individuals from negative and worrying thoughts and rumination, improving the retrieval of positive thoughts and allowing time away from negative or stressful aspects of everyday life, and especially, the COVID-19 pandemic itself. These moderating factors might also explain the protection effect of exercise on mental health (Mikkelsen et al., 2017).

Physical activity programmes to improve self-esteem to people of all ages can be effectively delivered at home by DVD (e.g. see Awick et al., 2017) or by You Tube (e.g. PE with Joe).

Peer Support

Moreover, people in social isolation should try to create peer support through social networking services by involving friends and relatives in their exercise routines or challenges.



The negative impacts of COVID-19 lockdown on mental health can be ameliorated by the use of exercise, which should be as vigorously promoted as social distancing itself.

In this context, keeping moving seems to be the key.


Thiago Matia, Fabio H Dominski and David F Marks (2020)

Food, Diets and Dieting


The world is full of contradictions, inconsistencies and inequities. On the one hand, it has been reported by the Food and Agriculture Organization of the United Nations (FAO, 2015) that 805million people are estimated to be chronically undernourished. Yet, it has been estimated that the volume of food produced is more than one and a half times what is needed to provide everybody on the planet with a nutritious diet (Weis, 2007). It is not about lack, it is about inequity. While 805 million starve, we also know that 1460 million are overweight or obese, and that number is increasing.

There is also water scarcity with 1.2 billion people lacking access to clean drinking water and 2.5 billion people having no access to a toilet, less than the number of people with a mobile phone (United Nations, 2015). As the world population increases from 7.3 billion today to around 9.6 billion in 2050 (+31.5%), the supply of fresh drinking water available will remain about the same. Yet, around 70 per cent of the world’s water is used in agriculture. Annual grain crops are planted on about 70 per cent of the world’s cropland and provide 80per cent of the world’s food (Pimentel et al., 2012), 70 per cent of which is stock feed for farm animals, which in turn produce dairy and meat.

Over the next 25 years, a lot more food will be needed for the extra 31.5 per cent and the only way it can be produced is through agriculture, creating a vicious circle. The FAO (2015) predicts that the global demand for livestock products will increase by 70 per cent by 2050 with an estimated 1 billion poor depending on livestock for food and income. The livestock sector contributes to human-induced Greenhouse Gas emissions for 14.5 per cent and is a large user of natural resources, especially water.

As Father Time waves his sickle over the remaining decades of this century, there will be a worsening water scarcity. Thanks in part to a ready supply of beef burgers, fried chicken, milk, eggs and cola. Many recent editorials in medical and scientific journals have addressed issues relating to food, diets and dieting (e.g. Drewnowski, 2014; Edmonds and Templeton, 2013; Fitzgerald, 2014; Gold and Graham, 2011; Ndisang et al., 2014; Pagadala and McCullough, 2012; Potenza, 2014; Sniehotta et al., 2014; Stuckler and Basu, 2013; The PLoS Medicine Editors, 2012; Yanovski, 2011).

Special Issue

The Special Issue on ‘Food, Diets and Dieting’ provides a state-of-the-art overview of psychological studies by international researchers on this topic area. The Call for Papers for a Special Issue on ‘Food, Diets and Dieting’ was timely; we received unprecedented interest with many high-quality submissions. Following peer review, the number of accepted papers finally reached the total of 42. The contributions have been divided into two sets for publication in the May and June 2015 issues of Special Issue: Food, diets and dieting. These publications in Journal of Health Psychology are complemented in our companion, open access journal, Health Psychology Open, by a theoretical review paper and a series of commentary papers (Marks, 2015).

According to the McKinsey Global Institute (2014) obesity is responsible for around 5 per cent of global deaths and the global economic impact is US$2.0trillion, or 2.8per cent of global gross domestic product (GDP), roughly equivalent to the impact from smoking or armed violence, war and terrorism. In the United States, in 2004, direct and indirect health costs associated with obesity were US$98 billion. That figure probably has doubled by now.

Depending on the source, it is reported that the direct medical cost of overweight and obesity combined has been estimated to be 5–10per cent of the US health care spend. 42million children under the age of 5 were overweight or obese in 2013. Prevalence of overweight or obesity in adults doubled from 6 per cent in 1980 to 12 per cent in 2008. By 2050, it is predicted that obesity will affect 60 per cent of adult men, 50 per cent of adult women and 25per cent of children making the United States, Britain and much of Europe a mainly obese society.

Globalization is Driver

The main driver of the obesity epidemic and increased prevalence of other non-communicable diseases is unregulated corporate globalization (Swinburn et al., 2011). From the point of view of human health, globalization flies a banner of progress and freedom yet brings illness and an early death to millions of people with non-communicable ‘diseases of affluence’. Transnational corporations are scaling up their promotion of tobacco, alcohol, cola and other sugary beverages, ultra-processed food and unhealthy commodities generally throughout low- and middle-income countries. Moodie et al. (2013) have observed that sales of unhealthy commodities across 80 low- and middle-income countries are strongly interrelated. They argue that wherever there are high rates of tobacco and alcohol consumption, there are also a high intake of snacks, soft drinks, processed foods and other unhealthy food commodities. Moodie et al. (2013) argued that the alcohol and ultra-processed food and drink industries are using similar strategies to the tobacco industry to undermine effective public health policies and programmes. Furthermore, it is suggested that unhealthy commodity industries should have no role in the formation of national or international policy for non-communicable disease policy. Therefore, it follows that the only evidence-based mechanisms that can prevent harm caused by unhealthy commodity industries are public regulation and market intervention.

Food Affordability

The work of Drewnowski and others has demonstrated a strong relationship between affordability of food and beverages and their energy density measured in terms of fat and sugar (Drewnowski, 2014; Drewnowski and Specter, 2004). A systematic review of 27 studies across 10 countries showed that a healthful diet costs around US$550 per year more than an unhealthy one (Rao et al., 2013). In England, another study suggested that the healthiest dietary pattern costs double the price of the least healthy, costing £6.63/day and £3.29/day, respectively (Morris et al., 2014). That is a difference of £1219 per annum.

The inverse relationship between income and prevalence of overweight and obesity follows from two related facts: (a) cheaper foods and drinks are energy-dense and (b) a healthful diet is unaffordable for the majority of people. In 2008, an estimated 1.46 billion adults worldwide had a body mass index (BMI) of 25kg/m2 or greater, and of these, 205million men and 297million women were obese. Taking into account, the rate of increase in obesity, this half-billion figure is projected to increase at least 30 per cent by 2050. The World Health Organization (WHO) (2014) estimates that around 3.4million adults die each year as a result of overweight or obesity. The WHO (2013) published a plan to halt the rise in diabetes and obesity as a part of a vision: ‘A world free of the avoidable burden of noncommunicable diseases’. WHO interventions revolve around ‘mobilizing sustained resources Marks 471 … in coordination with the relevant organizations and ministries’ which consists of high-level meetings between governmental representatives and publishing position statements.

Evidence and logic suggest that economic prosperity is the enabler for obesity and, furthermore, leading authorities have concluded that Obesity is the result of people responding normally to the obesogenic environments they find themselves in. Support for individuals to counteract obesogenic environments will continue to be important, but the priority should be for policies to reverse the obesogenic nature of these environments. (Swinburn et al., 2011) Policy reversals to reduce obesogenicity by regulation face robust resistance from the food and drinks industry. Yet without regulation to change the price imbalance between unhealthful and healthful foods, the obesity epidemic is unlikely to go away. In the meantime, hundreds of millions of individuals continue inexorably along the path of overweight and obesity, with the associated unpleasant illnesses and an early death. It follows that health care systems must be competent to offer effective interventions to prevent, treat and ameliorate the impact of overweight or obesity. Authorities decree that a ‘balanced diet’ with regular physical activity is of crucial importance to a healthy body. Yet, in spite of thousands of studies, hundreds of campaigns and scores of dedicated institutes and journals based on this creed, there are currently no validated public health interventions able to achieve sustained long-term weight loss. Today, the muchtouted idea of the ‘balanced diet’ seems little more than worn out myth. Some basic questions require answers: What is causing the obesity epidemic? What can be done about it? and What is the role of health psychologists (if any)? (Marks et al., 2015; Marks, in press). The obesity epidemic is comparable in importance to the smoking epidemic. Arguably, it will prove to be even more significant in human history than smoking. It took 50 years of consolidated pressure to reduce the prevalence of smoking related diseases. Progress has been frustratingly slow. Still, in 2015, only one industrialized country in the world has plain or standard packaging of cigarettes (Australia) with a second one planning to follow next year (England). With no significant interventions on the horizon for obesity prevention, for example, unhealthful food taxation, the obesity epidemic can continue unabated to run its course, until food and water shortages have their ultimate impact on human society.

Enough Knowledge Now to Tackle Obesity

There is enough knowledge now to tackle the obesity epidemic. Unfortunately our political leaders lack the spine to do what is necessary. Our market-led governance is in the pocket of the paymasters who influence the election of our presidents and prime ministers. If the food chain could be rationally developed, the food and water crises could be curbed within two decades from now. This Special Issue contains a collection of in-depth psychological studies on food, diets and dieting. These studies are relevant to the issue of why certain foods are eaten or avoided by individual consumers and how the choices of consumers are influenced by family, social and economic conditions. Diets and dietary changes involve complex systems of variables which operate on a mass scale. Improved understanding of psychological functioning around food, diets and dieting holds one key to improving nutritional health. A better understanding of behaviour alone is not enough; changes to the food environment are also necessary. Our governmental leaders need to wake up, loosen their ties to their industrial paymasters and take effective action.


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First published in the Journal of Health Psychology 2015