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.


Drewnowski A (2014) Healthy diets for a healthy planet. The American Journal of Clinical Nutrition 99(6): 1284–1285.

Drewnowski A and Specter SE (2004) Poverty and obesity: The role of energy density and energy costs. The American Journal of Clinical Nutrition 79(1): 6–16.

Edmonds EW and Templeton KJ (2013) Childhood obesity and musculoskeletal problems: Editorial Clinical Orthopaedics and Related Research 471(4): 1191–1192.

Fitzgerald DA (2014) Mini-symposium: Childhood obesity and its impact on respiratory wellbeing: Editorial title: Childhood obesity is the global warming of healthcare. Paediatric Respiratory Reviews 15(3): 209–284.

Food and Agriculture Organization of the United Nations (FAO) (2014) The State of Food Insecurity in the World: Strengthening the Enabling Environment for Food Security and Nutrition. Rome: FAO. Available at: http://

Food and Agriculture Organization of the United Nations (FAO) (2015) Livestock and the environment. Available at: livestock-environment/en/

Gold MS and Graham NA (2011) Editorial: Hot topic: Food Addiction & Obesity Treatment Development (Executive Guest Editors: Mark S Gold and Noni A Graham). Current Pharmaceutical Design 17(12): 1126–1127.

McKinsey Global Institute (2014) Overcoming obesity: An initial economic analysis. Discussion paper. London. Available at: http://www. ficheros/025183D9.pdf

Marks DF (2015) Homeostatic theory of obesity. Health Psychology Open. Marks DF, Murray M, Evans B, et al. (2015) Health Psychology: Theory, Research and Application (4th edn). London: SAGE.

Moodie R, Stuckler D, Monteiro C, et al. (2013) Profits and pandemics: Prevention of harmful effects of tobacco, alcohol, and ultraprocessed food and drink industries. The Lancet 381(9867): 670–679.

Morris MA, Hulme C, Clarke GP, et al. (2014) What is the cost of a healthy diet? Using diet data from the UK Women’s Cohort Study. Journal of Epidemiology and Community Health 68(11): 1043–1049.

Ndisang JF, Vannacci A and Rastogi S (2014) Oxidative stress and inflammation in obesity, diabetes, hypertension, and related cardiometabolic complications. Oxidative Medicine and Cellular Longevity 2014: 506948.

Pagadala MR and McCullough AJ (2012) Editorial: Non-alcoholic fatty liver disease and obesity: Not all about BMI. The American Journal of Gastroenterology 107: 1859–1861.

Pimentel D, Cerasale D, Stanley RC, et al. (2012) Annual vs. perennial grain production. Agriculture, Ecosystems & Environment 161: 1–9.

Potenza MN (2014) Obesity, food, and addiction: Emerging neuroscience and clinical and public health implications. Neuropsychopharmacology 39(1): 249–250.

Rao M, Afshin A, Singh G, et al. (2013) Do healthier foods and diet patterns cost more than less healthy options? A systematic review and metaanalysis. BMJ Open 3: e004277.

Sniehotta FF, Simpson SA and Greaves CJ (2014) Weight loss maintenance: An agenda for health psychology. British Journal of Health Psychology 19: 459–464.

Stuckler D and Basu S (2013) Getting serious about obesity. BMJ: British Medical Journal 346: f1300.

Swinburn BA, Sacks G, Hall KD, et al. (2011) The global obesity pandemic: Shaped by global drivers and local environments. The Lancet 378(9793): 804–814.

The PLoS Medicine Editors (2012) PLoS Medicine series on Big Food: The food industry is ripe for scrutiny. PLoS Medicine 9(6): e1001246.

United Nations (2015) Water Scarcity. Available at: shtml

Weis T (2007) The Global Food Economy. London: Zed Books. World Health Organisation (WHO) (2014) Obesity and overweight. Fact Sheet No 311. Available at: fs311/en/ factsheets/fs311/en/

World Health Organization (WHO) (2013) Global Action Plan for the Prevention and Control of Noncommunicable Diseases 2013–2020. Geneva: WHO.

Yanovski SZ (2011) Obesity treatment in primary care – Are we there yet. New England Journal of Medicine 365(21): 2030–2031.

First published in the Journal of Health Psychology 2015

“Brilliant new book”

Reviewed by Ewan McDougall:
“When I first read David Marks brilliant new book Obesity, there was a story on Radio New Zealand that two thirds of Auckland adults were now over weight or obese and the statistic for children was not much better. You don’t have to be an epidemiological genius to see that this will become a major problem for us and for other Western countries which are in the throes of an obesity epidemic.
David Marks presents a fresh, clear-eyed analysis of the complex causes of this epidemic: social, economic and psychological. He discusses the role of neoliberal capitalism in the promotion of poor, calorie rich food and animal products. The psychologist’s discussion of a person’s ‘circle of discontent’ which undermines homeostasis and then ‘feeds’ the spiral of unhealthy eating is fascinating and rings true. And he provides a refreshing solution including the adoption of veganism. The book is lucid and courageous and is the best analysis of a harrowing problem in the world, and a call to action, which I have read.


Dyshomeostasis in human feeding

In an environment that promotes widespread body dissatisfaction, angst and depression, homeostatic feedback loops are producing excessive consumption of unhealthy processed foods that over a protracted period causes obesity in large numbers of vulnerable people. Multiple clinical studies in different areas of medicine demonstrate the primary role of homeostasis in healthy functioning and the consequences of dyshomeostasis. Homeostasis can be overloaded or overridden with too strong a flow of inputs or outputs that disrupt its normal functioning: ‘The homeostatic behaviour of inflow controllers breaks down when there are large uncontrolled inflows, whereas outflow controllers lose their homeostatic behaviour in the presence of large uncontrolled outflows’ (Drengstig et al., 2012). Homeostasis can be disrupted anywhere, and perturbations will inevitably occur in normal functioning (Richards, 1960).

There are many examples of dyshomeostasis in clinical medicine. Well-known to psychologists, Hans Selye reported that a persistent environmental stressor (e.g. temperature extremes), together with an associated homeostatic hormonal response, leads to tissue injury that he termed a ‘disease of adaptation’ (Selye, 1946). Intestinal homeostasis breaks down in inflammatory bowel disease (Maloy and Powrie, 2011) and in the microbial ecology of dental plaque causing dental disease (Marsh, 1994). This form of dyshomeostasis can result from local infection and inflammation and give rise to complications that affect the nervous and endocrine systems (Maynard et al., 2012). An altered balance between the two major enteric bacterial phyla, the Bacteroidetes and the Firmicutes, has been associated with clinical conditions. Within the microbiota of the gut, obesity has been associated with a decreased presence of bacteroidetes and an increased presence of actinobacteria (Ley, 2010; Turnbaugh and Gordon, 2009). Kamalov et al. (2010) proposed a dyshomeostasis theory of congestive heart failure. Craddock et al. (2012) suggested a zinc dyshomeostasis hypothesis of Alzheimer’s disease.

Homeostasis regulation within the endocrinal and central nervous systems has been associated with feeding control. Cortical areas conveying sensory and behavioural influences on feeding provide inputs to the nucleus accumbens (NAc) and the lateral hypothalamic area (LHA) is the site of homeostatic and circadian influences (Saper et al., 2002). Hormones such as leptin circulate in proportion to body fat mass, enter the brain and act on neurocircuits that govern food intake (Morton et al., 2006). Through direct and indirect actions, it is hypothesized that leptin diminishes the perception of food reward while enhancing the response to satiety signals generated during food consumption that inhibit feeding and lead to meal termination.

Another important hormone is ghrelin which is the only mammalian peptide hormone able to increase food intake. Interestingly, ghrelin also responds to emotional arousal and stress (Labarthe et al., 2014; Müller et al., 2015). During chronic stress, increased ghrelin secretion induces emotional eating by acting at the level of the hedonic/reward system. As ghrelin has anxiolytic action in response to stress, this adaptive response may contribute to control excessive anxiety and prevent depression (Labarthe et al., 2014). In obesity, studies have shown a reduced ability to mobilize ghrelin in response to stress or central ghrelin resistance at the level of the hedonic/reward system which may explain the inability to cope with anxiety and increased susceptibility to depression (Figure 1). Reciprocally, studies have shown that people with depression have increased susceptibility to obesity and eating disorders (Marks, 2015).

Figure 1. Model of hedonic/reward response to ghrelin after chronic stress in relation to anxiety and depression. Reproduced from Labarthe et al. (2014).

During chronic stress, increased ghrelin secretion induces emotional eating as hedonic reward. Ghrelin has anxiolytic actions in response to stress; this adaptive response helps to control excessive anxiety and prevent depression. In obesity, a lower ability to mobilize ghrelin in response to stress or central ghrelin resistance at the level of the hedonic/reward system may explain the inability to cope with anxiety and increased susceptibility to depression. Reciprocally, people suffering from depressed show increased susceptibility to obesity or eating disorders (due to an altered hedonic/reward response). Elevated ghrelin may also contribute to alcohol/drug craving as higher ghrelin levels correlate with greater alcohol craving.

In addition to leptin and ghrelin, other lipid messengers that modulate feeding by sending messages from the gut to the brain have been identified. For example, oleoylethanolamine has been associated with control of the reward value of food in the brain (Lo Verme et al., 2005; Tellez et al., 2013). Mice fed a high-fat diet had abnormally low levels of oleoylethanolamine in their intestines and did not release as much dopamine compared to mice on low-fat diets. Thus, alterations in gastrointestinal physiology induced by excess dietary fat may be one factor responsible for excessive eating in the obese (Tellez et al., 2013).

Extracted from Marks (2016)

A General Theory of Obesity

Inside every one us there exists a tension between comfort and discontent. When we assuage the discontent, we find comfort. When we resist comfort, the discontent builds stronger. This eternal struggle is an aspect of the human condition that creates a vicious and unforgiving circle. Within it lies a significant key to human nature, and to the nature of all sentient beings, the ‘Yin and Yang’ of life…it helps to explain the human struggle with overweight, obesity and the addictions.

Once the causes of obesity are fully understood, the obesity epidemic can be stopped. My book takes a step towards that goal. I propose an explanatory theory of an objective issue of undeniable importance to human beings – the obesity epidemic. The ideas are drawn from a range of disciplines including economics, endocrinology, epidemiology, neurobiology, nutrition, physiology, policy studies and psychology. The theory focuses on a universal feature of living beings, homeostasis, and the potential for its disruption, dyshomeostasis.


The evidence points to ‘Obesity Dyshomeostasis’ as a problematic human response to contemporary conditions of living. Similar to racism, sexism and ageism, the current trend towards ‘blaming and shaming’ individual sufferers of obesity and overweight contributes to the problem. Only by reversing this form of prejudice, and the associated environmental conditions, will the obesity epidemic have any chance of being resolved (Marks, 2015a, 2016).

Summary of argument:

Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium using feedback loops for optimum functioning of the organism. Dyshomeostasis, a disturbance of homeostasis, causes overweight and obesity, is estimated to be present today in more than two billion people world-wide.

Obesity Dyshomeostasis is associated with a ‘Circle of Discontent’, a system of feedback loops connecting weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent is consistent with an extensive evidence-base.

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Obesity Dyshomeostasis occurs when homeostatic control of eating is overridden by hedonic reward. Appetitive hedonic reward is a natural response to an obesogenic environment containing endemic stress and easily accessible, high-energy foods and beverages. In a time of plentiful and cheap food, people eat more to comfort their discontents than purely for hunger. The comfort foods and beverages that are snacked on almost limitlessly are nutritionally deleterious to the health.

The objectives are: (i) To define, describe and discuss the concepts of psychological homeostasis and dyshomeostasis and their relevance to overweight, obesity, the addictions and chronic stress; (ii) To propose a General Theory of Well-Being founded on the construct of psychological homeostasis; (iii) Within the general theory, to specify the Obesity Dyshomeostasis Theory (ODT) of overweight and obesity; (iv) To summarize the body of evidence that is supportive of the general theory and the ODT; (v) To describe interventions for preventing overweight and obesity based on the ODT.

Obesity dyshomeostasis is mediated by the prefrontal cortex, amygdala and HPA axis with ghrelin providing the signalling for feeding dyshomeostasis, affect control and hedonic reward. Dyshomeostasis plays a causal role in obesity, the addictions and chronic conditions and is fueled by negative affect and chronic stress. Prevention and treatment efforts that target dyshomeostasis provide strategies for reducing adiposity, ameliorating the health impacts of addiction, and raising the quality of life in people suffering from chronic conditions and stress.

A four-armed strategy to halt the obesity epidemic consists of eliminating the causes of overweight and obesity: (1) Resisting and putting a stop to a culture of victim-blaming, stigma and discrimination; (2) Resisting and devalorizing the thin-ideal; (3) Resisting and reducing consumption of energy-dense, low nutrient foods and drinks; (4) Improving access to plant-based diets. If fully implemented, these interventions should be competent to restore the conditions for homeostasis in billions of people and the obesity epidemic could be halted.

Extracted from Obesity. Comfort vs Discontent