Karen Budewig, Fiona Crawford, Neil Hamlet, Phil Hanlon, Jill Muirie and David Ogilvie
All authors contributed equally to this article
First published March 2004 at www.obesescotland.org.uk
Contents
Obesity: a time bomb for public health
The human being: an obesogenic organism
Treating the obesogenic organism
Our world: an obesogenic environment
Modifying the obesogenic environment
Scotland: an obesogenic society
What are we going to do about it?
References
Obesity: a time bomb for public health
More and more people are becoming overweight and obese. If we don't do something about this, we can expect to see serious effects on the future health of our population. Whatever we're doing at the moment clearly isn't working.
We are now witnessing a remarkable phenomenon - an epidemic of obesity. [1] This epidemic has been developing slowly for a few decades, but it has only recently begun to attract attention as a public health problem. Suddenly, obesity is a hot topic for health professionals, politicians and the media, and this heightened level of awareness is clearly an important step towards addressing the problem. But so far, we have tended to concentrate on apparently simple solutions that may, in fact, be unlikely to produce large-scale changes in population health unless we also confront those aspects of our society that are maintaining and driving the obesity epidemic. In this paper, we offer a stepwise analysis of why we're becoming more obese despite our good intentions, with the aim of stimulating a more sophisticated debate about how we can reverse this situation.
Obesity is a condition characterised by an excess of body fat. [2] We define obesity using the body mass index (BMI), which is a person's weight in kilograms divided by the square of their height in metres. For adults, overweight is defined as a BMI of greater than 25 and obesity is defined as a BMI of greater than 30. To give an example in more familiar terms, a person who is 1.65 m (5' 5") tall would be considered overweight if they weighed 68 kg (10 st 10 lb) and obese if they weighed 82 kg (12 st 13 lb).
The health risks of obesity are serious. People who are obese are more likely to develop a range of chronic conditions including osteoarthritis, high blood pressure, diabetes, heart disease and some cancers. [2] Children are not immune from these risks. Until recently, type 2 diabetes was only seen in adults, but now some adolescents are developing this condition, which can lead in later life to serious consequences such as heart disease, stroke, kidney failure and blindness. [3] Nor are the effects limited to physical illnesses. For example, obese children (especially girls) are more likely to show evidence of psychological distress than children who are not obese. [4]
The proportion of people who are overweight or obese is rising fast. The World Health Organisation now estimates that there are more obese people in the world than underweight people. [5] Obesity is more common in the UK than in most other European countries, the proportion of children who are overweight is rising, and Scottish children and adults are more likely to be obese than their English counterparts. [6-10] The potential for this epidemic to spread rapidly is graphically illustrated in this series of slides showing the speed with which obesity has increased among adults in the United States.
We lack good evidence about what works in preventing obesity in populations. There have been few high quality scientific studies of interventions, and most population-based preventive programmes that have been rigorously evaluated have not shown favourable effects on the prevalence of obesity, especially among adults. [3, 11-13]
The human being: an obesogenic organism
We're stuck with the metabolic and behavioural legacy of our evolutionary history. Human beings are naturally susceptible to becoming obese when food is readily available and life is not physically demanding, although some people are more susceptible than others. In order to avoid becoming obese, we have to battle against our instincts.
From a biological point of view, whether or not each of us becomes obese depends on the balance between our energy input and output. Our bodies have sophisticated mechanisms that can regulate body weight by adjusting energy intake to match energy expenditure and vice versa.
The evidence about energy input is confusing. Some international studies have suggested that over the past few decades, people's energy intake has increased only by a small amount, if at all. [14-16] But these findings seem implausible when we consider trends in food availability. For example, the average daily supply of food energy per head has been increasing since the 1960s in most parts of the world, [17] and portion sizes have increased over the same period, at least in the United States. [18] The increased energy contained in our food supply must be going somewhere.
On the other hand, a decline in daily levels of physical activity is widely accepted as a major factor contributing to the obesity epidemic in both developed and developing countries. [14-16, 19] Our increased reliance on cars, washing machines, lifts and computers has substantially reduced the amount of energy we need to expend on our daily activities, while one of our favourite leisure pursuits, watching TV, is not only sedentary but is also often accompanied by eating. [3, 14]
We don't fully understand what causes obesity. We have identified many genes that may be associated with obesity, [3] and the results of twin studies suggest that about two-thirds of the variations in BMI between people may be due to genetic factors. [20] We also know that children can be affected by the health and nutrition of their mothers during pregnancy and by their experiences in early life. For example, obesity is more common among children of deprived families [4, 9] and there is a relationship between maternal obesity, birth weight and obesity later in life, [3, 9, 21, 22] whereas babies who are breastfed are less likely to become obese. [23] These factors may help to explain why some people become obese and others don't, but they are unlikely to explain why obesity has suddenly become much more common. In particular, genetic factors alone cannot account for the obesity epidemic because the genetic composition of the population as a whole changes extremely slowly. [24]
For a more plausible explanation, we need to review our history. Our physiology was formed a long time ago when food was scarce and we needed large amounts of energy in order to find food and stay alive - our ancestors are estimated to have expended about 1000 kcal per day in physical activity. Human beings adapted to these circumstances by eating food whenever it was available and conserving energy by moving only when necessary. This strategy of storing and conserving energy made perfect sense at the time, but it makes much less sense now in a society where food is easily come by and the average sedentary person only needs to expend about 300 kcal per day in physical activity. [24]
We are stuck with the metabolic and behavioural legacy of our evolutionary history. Experiments with both adults and children have shown that when people are offered test meals with higher energy content or larger portions, they consume significantly more energy [25, 26] - suggesting that we have an instinct to overconsume when given the chance. On the other hand, although there is some degree of professional consensus that we should concentrate our efforts on strategies to increase physical activity, [11] the authors of a recent review concluded that they could not find any evidence of a physiological drive to engage in physical activity for its own sake [19] - an observation that has profound implications for any health promotion programme.
Treating the obesogenic organism
Campaigns, diets, drugs and operations may work for some people some of the time, but if these are truly effective solutions to obesity, why is the population continuing to gain weight?
Most people know about healthy eating and the need for exercise, but simply knowing that we should battle against our instincts is not sufficient to bring about change. Recent reviews have suggested that we should aim to increase population energy expenditure in an attempt to regain the balance between energy inputs and outputs that our ancestors had, [24] and that since we are unlikely to be able to rely on instinctive weight regulation, we should foster the development of cognitive skills to regulate weight. [19] These proposals build on a long-established rational prescription to the effect that people who are overweight must be consuming more energy than they are expending, and therefore that if they correct this imbalance, the problem will be solved. [27]
We have been offering solutions based on this idea for years - either telling people what to do (healthy eating campaigns, diets, prescribing exercise) or offering technical fixes (drugs to suppress appetite, operations to reduce the size of the stomach). We often read about "slimmers of the month" and other personal success stories, but the population as a whole continues to gain weight. This may be because we have treated obesity as a personal matter, for which we have offered personal advice - take more exercise, eat fewer calories. Although personal advice may be effective for an individual person when followed consistently, at least in the short term, it often fails to recognise the complex reality of most people's lives. These approaches do not seem to be working at a population level.
Our world: an obesogenic environment
We now find ourselves in an environment where we are encouraged to eat more and exercise less. Since we're naturally inclined to go along with both of these influences, these are ideal conditions for nurturing obesity.
The speed with which obesity has become a global epidemic suggests that environmental or social influences have changed and are promoting weight gain in susceptible people. [28] Terms such as toxic environment [3] and obesogenic environment [27, 29] have been used to describe some of these influences.
Examples of environmental influences that may encourage us to eat more than we need include the marketing of energy-dense drinks and snacks, for example through television advertising and vending machines in schools, and the documented increase in portion sizes in US restaurants, [30] where an average meal may provide up to 2000 kcal - almost the entire recommended daily intake for most adults. [3, 29] These environmental influences have not arisen by accident. Capitalist economies overproduce food in order to further economic growth and the interests of industry and its shareholders. The estimated average global daily supply of food energy per head increased from about 2350 kcal in the 1960s to about 2800 kcal in the 1990s. [17] The excess energy produced has to be incorporated into the food chain somewhere and sold to consumers. It is therefore inevitable that we face a constantly available array of tempting foods full of energy. On the other hand, the amount of sedentary time spent watching TV by children in the UK has doubled since the 1960s [31] and most European adults now spend more than three hours of each working day sitting. [32] In an environment designed around the car, our lives have simply become less active. In order to expend energy, we increasingly seem to need to buy special equipment or go to a special place such as a gym, swimming pool or cycle path, but the costs of doing these things may form a barrier for some people. [33]
It is not surprising that our obesogenic organism should have problems coping with an environment that exerts constant pressure to increase energy intake and to decrease energy expenditure. [1, 34-36] The rise in obesity suggests that the effects of our obesogenic environment are overriding the biological regulatory mechanisms in more and more people. [28]
Modifying the obesogenic environment
We try to modify our environment in order to make it easier for people to make healthier choices, but most of the changes we have tried to make have been marginal and ignore the fact that we have created our environment to reflect the values of our society.
It has become an axiom of health promotion that we should try to create supportive environments in which the healthier choices are made the easier choices. [5] We have therefore tried to move on from solutions focused on individual people to making changes to our physical and social environments to encourage people to eat more wisely and to expend more energy - such as offering free fruit in schools, improving labelling on foods, providing free swimming for children and building cycle paths.
It is theoretically possible that changes to the environment could shift the behaviour of large numbers of people and prevent them from gaining weight if the changes were big enough. But many of the adjustments we have tried to make to our environment have been quite marginal. Sometimes this reflects an unwillingness to address conflicts of interest - for example, the access to consumers that commercial organisations gain from sponsoring state education. [3, 29, 37] At other times, our approach can give the impression that our environment, like our energy-conserving instincts, is something that we must battle against. But our environment has not been imposed on us. We have created it to reflect the values we have chosen as a society.
Scotland: an obesogenic society
The relationships between food, physical activity, body shape and happiness have become confused and contradictory. We now see food as one of many commodities that we must buy in order to further personal happiness and economic growth. At the same time, we're trying to buy health, fitness, weight loss and the perfect body. We don't seem able to handle the choices we have created for ourselves.
Many people still remember a time when food was relatively scarce. During the depression and the years of war rationing, food was quite plain, so items like cakes and biscuits were considered a real "treat". Guests visiting someone else's home would always be offered food, but it was polite to refuse until the hosts "insisted" - thereby reassuring their guests that there really was enough food in the house to share.
After rationing ended, these behaviours continued even though food became much more plentiful, affordable and diverse. We became able to enjoy high-energy "treats" much more frequently, and we continued to "insist" that guests should eat long after the social purpose of this insistence became redundant. Throughout the second half of the twentieth century, we also developed heightened expectations of what we could achieve for ourselves and our families through our careers, recreational activities and personal development. Pursuing these goals has meant that we now spend less time on shopping, preparing, sharing and enjoying food and have turned increasingly to convenience foods that can be eaten quickly and at times and places to suit each of us individually. This convenience may come at a price: there is now some evidence that children in families who sit down to dinner together have healthier diets. [38]
In subsistence agricultural economies, food is seen as a fuel by which the next day's labours are achieved. For example, in rural Nepal, distances are estimated in bhats, the number of rice meals required to make the journey. But in our consumerist economy, the significance of food has changed. Instead of working in order to produce things, to provide for others, or to make a difference to society, many of us now seem to be working primarily to earn money in order to consume products - not only food, but also leisure, knowledge, or experiences - to enhance our personal enjoyment and satisfy our search for meaning. This has almost become a social duty; at a time of national crisis after the 9/11 terrorist attacks, the US President specifically asked for his citizens' continued participation and confidence in the American economy. [39] We have responded to this shift in focus from production to consumption by encouraging the growth of industries that market all manner of things including entertainment, cosmetics, fashions, diets, convenience foods and opportunities for physical activity. Increasingly, we buy meals instead of making them, and drive to gyms to buy exercise instead of walking or cycling in our everyday activities.
In our commodified, consumerist society, the relationships between food, physical activity, body shape and happiness have become confused and contradictory. Eating well can be a symbol of achievement and status, but so can a fashionably thin physique. We want to acquire the stereotypically perfect body image promoted in advertising, but in an environment where food is plentiful we perceive moderation as deprivation. We have always enjoyed energy-dense foods that we used to see as a reward or treat, but many of these have now become daily staples as a result of greater affluence, availability and targeted marketing. We have produced an abundance of "healthy" substitute foods that contain less salt, fat or sugar than the original "bad" foods, but for some people, eating these "good" foods may induce a feeling of self-imposed deprivation and reinforce their preoccupation with food and body shape.
Compared with the restrictive traditions and social controls of nineteenth- and twentieth- century society, we now have enormous choice and autonomy in how we conduct our lives, [40] but we seem to be having great difficulty in handling this autonomy, either by exercising our own self-control or by teaching the necessary cognitive skills to our children.
What are we going to do about it?
Our current approaches to the emerging obesity epidemic are not working, may be unlikely to have much effect, and may run the risk of exacerbating the problem and increasing social inequalities in health. We need to confront our collective state of denial about the problem and develop a more ambitious idea of what an intervention to prevent obesity might be - we need to change the way our society deals with food, physical activity and body shape.
We urgently need to do something to reverse the growth of the obesity epidemic in Scotland. Aside from the technical medical solutions we offer people with established weight problems, our current policy approaches to preventing obesity are based either on trying to treat the obesogenic organism by encouraging individuals to modify their lifestyles, or on trying to modify the obesogenic environment to increase the availability of healthier choices. [41-43] We could just carry on doing these things, but we envisage three main problems.
The first problem is that we can't really expect to modify individual behaviour or the environment very much unless we acknowledge and confront the values of our society that underlie them. Treatments such as drugs and operations and the search for genetic silver bullets appeal to our desire for instant solutions, but may be blind alleys along which large quantities of resource could be poured with little overall benefit to the population as a whole. Meanwhile, diets can be dispiriting and costly for individuals and are infamous for their high rates of recidivism. [44-45]
The second problem is that we may run the risk of making things worse. The feminist psychotherapist Susie Orbach claims that more than half the female population aged from 15 to 50 experiences some form of eating problem. She believes that many women have lost the ability to react to normal hunger signals to tell them when to eat, and instead are trapped in a compulsive, dysfunctional relationship with food, struggling to achieve cultural stereotypes of ideal body shape in the face of overflowing supermarket shelves. Orbach argues that diets and other individual weight-reduction schemes simply reinforce the problem, substituting one form of compulsive behaviour (overeating) with another (dieting). [44, 46, 47] Her analysis raises the worrying possibility that healthy eating campaigns and some other behaviour change interventions could simply add to the obesity problem in the long term by increasing our obsession with food and body shape, contributing to a vicious spiral whereby we gain weight, fail to respond effectively to an intervention, lose self esteem and gain more weight.
The third problem is that if we concentrate on trying to modify individuals and their environments, we may run the risk of increasing social inequalities in health. We know that in some areas of health promotion, the better-off are more likely to respond to initiatives than poorer people. [48] Obesity is already more common in the more deprived sections of our society. [4, 9] If we allow a situation to continue in which people have to actively resist social pressures to overconsume and have to pay for the opportunity to exercise safely, we could see an increasing polarisation of Scottish society into a well-off elite, who exercise at expensive health clubs and exhibit fashionable moderation at the dining table, and a less healthy majority who lack the money, opportunity or motivation to engage with the interventions we are offering.
In summary, we have argued that our current responses to the emerging obesity epidemic are not working, may be unlikely to have much effect, and may run the risk of exacerbating the problem and increasing social inequalities in health. We have taken one critical step in identifying the obesogenic environment as part of the problem, but we now need to take the next logical step and begin to address the fundamental values of our society that have given rise to that environment and to the meanings that food and physical activity hold for us. We do not suggest that trying to recapture the values of a nostalgic "golden age" is either possible or desirable. Instead, we need to adopt a more ambitious idea of what an intervention to prevent obesity might be. We acknowledge that evidence about the effectiveness of environmental modifications in preventing obesity is currently very limited and may accrue in time, but we suggest that their overall impact on the problem is likely to be quite limited unless we can begin to change the fundamental economic and social rules by which we produce and consume food and understand physical activity and body shape. In short, we need to confront our collective state of denial about how we arrived at this situation and start thinking honestly about what needs to be done at a societal level to change it.
Obesity is an urgent public health problem in Scotland for which no one yet has a credible solution. In this paper, we have tried to stimulate some fresh thinking about the issues we need to confront. We want more people to join the debate and help to develop more radical approaches.
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