Obesity in children and young people: a crisis in public health

Ten per cent of the world's school-aged children are estimated to be carrying excess body fat (Fig. 1), with an increased risk for developing chronic disease. Of these overweight children, a quarter are obese, with a significant likelihood of some having multiple risk factors for type 2 diabetes, heart disease and a variety of other co-morbidities before or during early adulthood. The prevalence of overweight is dramatically higher in economically developed regions, but is rising significantly in most parts of the world. Prevalence of overweight and obesity among school-age children in global regions. Overweight and obesity defined by IOTF criteria. Children aged 5–17 years. Based on surveys in different years after 1990. Source: IOTF (1). In many countries the problem of childhood obesity is worsening at a dramatic rate. Surveys during the 1990s show that in Brazil and the USA, an additional 0.5% of the entire child population became overweight each year. In Canada, Australia and parts of Europe the rates were higher, with an additional 1% of all children becoming overweight each year. The burden upon the health services cannot yet be estimated. Although childhood obesity brings a number of additional problems in its train – hyperinsulinaemia, poor glucose tolerance and a raised risk of type 2 diabetes, hypertension, sleep apnoea, social exclusion and depression – the greatest health problems will be seen in the next generation of adults as the present childhood obesity epidemic passes through to adulthood. Greatly increased rates of heart disease, diabetes, certain cancers, gall bladder disease, osteoarthritis, endocrine disorders and other obesity-related conditions will be found in young adult populations, and their need for medical treatment may last for their remaining life-times. The costs to the health services, the losses to society and the burdens carried by the individuals involved will be great. The present report has been written to focus attention on the issue and to urge policy-makers to consider taking action before it is too late. Specifically, the report: reviews the measurement of obesity in young people and the need to agree on standardized methods for assessing children and adolescents, and to compare populations and monitor trends; reviews the global and regional trends in childhood obesity and overweight and the implications of these trends for understanding the factors that underlie childhood obesity; notes the increased risk of health problems that obese children and adolescents are likely to experience and examines the associated costs; considers the treatment and management options and their effectiveness for controlling childhood obesity; emphasizes the need for prevention as the only feasible solution for developed and developing countries alike. This document reflects contributions from experts working in a wide range of circumstances with a diversity of approaches, but with many shared opinions. The report has been endorsed by the Federation of International Societies for Paediatric Gastroenterology, Hepatology and Nutrition (FISPGHAN) and the International Paediatric Association (IPA). Health professionals are aware that the rising trends in excess weight among children and adolescents will put a heavy burden on health services (for example, 10% of young people with type 2 diabetes are likely to develop renal failure by the time they enter adulthood, requiring hospitalization followed by life-long dialysis treatment (2). Health services, especially in developing countries, may not easily bear these costs, and the result could be a significant fall in life expectancy. In industrially developed countries, children in lower-income families are particularly vulnerable because of poor diet and limited opportunities for physical activity. There may also be an ethnic component; for example, in the USA the prevalence of overweight among children aged 4–12 years rose twice as fast in Hispanic and African–American groups compared with white groups over the period 1986–1998 (3). In developing nations child obesity is most prevalent in wealthier sections of the population. However, child obesity is also rising among the urban poor in these countries, possibly due to their exposure to Westernized diets co-inciding with a history of undernutrition. Such rapid changes in the numbers of obese children within a relatively stable population indicate that genetic factors are not the primary reason for change. Some migration of populations may account for a proportion of the epidemic, but cannot account for it all. Although studies of twins brought up in separate environments have shown that a genetic predisposition to gain weight could account for 60–85% of the variation in obesity (4), for most of these children the genes for overweight are expressed where the environment allows and encourages their expression. These obesity-promoting environmental factors are sometimes referred to as ‘obesogenic’ (or ‘obesigenic’). Put graphically, a child's genetic make-up ‘loads the gun’ while their environment ‘pulls the trigger’ (5). A genetic predisposition to accumulate weight is a significant element in the equation, but its importance might best be viewed from another perspective: the genes that predispose for obesity are likely to be commonplace, with only a small proportion of children able to resist gaining weight in an obesogenic environment. The changing nature of the environment towards greater inducement of obesity has been described in WHO Technical Report (6) on chronic disease as follows: ‘Changes in the world food economy have contributed to shifting dietary patterns, for example, increased consumption of energy-dense diets high in fat, particularly saturated fat, and low in unrefined carbohydrates. These patterns are combined with a decline in energy expenditure that is associated with a sedentary lifestyle—motorized transport, labour-saving devices at home, the phasing out of physically demanding manual tasks in the workplace, and leisure time that is preponderantly devoted to physically undemanding pastimes.’ (pp. 1–2) This emphasis on the environmental causes of obesity leads to certain conclusions: first that the treatment for obesity is unlikely to succeed if we deal only with the child and not with the child's prevailing environment, and second that the prevention of obesity – short of genetically engineering each child to resist weight gain – will require a broad-based, public health programme. A doctor presented with an obese child must nevertheless attempt some form of remedial intervention to prevent the child's health deteriorating. The aim is to stabilize and hopefully reduce that child's accumulation of body fat, using a range of approaches discussed in the next few paragraphs. For a great majority of obese patients, the first point of contact is with a primary care physician or a public health nurse. Yet the relevant training in bariatric methods (methods related to the assessment, prevention and treatment of obesity) at the undergraduate level remains inadequate. Two national surveys in the USA conducted over 10 years, indicated that paediatric obesity was the most wanted topic for continuing medical education (7). For children who are moderately overweight, measures to prevent further weight gain, combined with normal growth in height, can be expected to lead to a decrease in BMI – i.e. children may be able to ‘grow into’ their weight. For the more seriously obese child, treatment regimes are largely palliative and designed to manage and control rather than resolve the problem. Weight control and improved self-esteem may be achieved, but the child is likely to remain seriously overweight and at risk of chronic disease throughout his or her life. The clinical management of obese children may require an extended amount of time and the assembly of a professional team including a dietitian, exercise physiologist and psychologist in addition to the physician. As paediatric obesity becomes more common, patient management may not be restricted to obesity clinics and other forms of management may be developed. Obesity clinics may be necessary for morbid obesity, but less severe forms of obesity may be better managed in primary care settings by a range of health practitioners. Obesity control in adults relies on a range of options: improvements in nutritional habits, raised levels of physical activity, behavioural modification and psychotherapy, pharmaceutical treatment and as a last resort, surgery. These options can be used alone or in combination. For children, neither surgery nor drug therapy can currently be recommended unless within a closely monitored research study (8). Of the remaining choices, no single method will ensure success, although some consensus exists. For example, reducing the time engaged in sedentary activities (such as watching television or playing computer and video games) has been shown to facilitate better treatment outcome (9). Dietary interventions in combination with exercise programmes have been reported to have better outcomes than dietary modulation alone. Exercise programmes alone without dietary modification are unlikely to be effective, because increased energy expenditure is likely to be matched by increased energy intake (10). A whole-family approach also appears vital, with several studies showing that outcomes are improved if the parents are engaged in the process, or even are the key instigators of the process, at least for younger children (11). Very strict dietary limitations were reported to have better short-term results than moderate dietary limitations. However, strictly modified diets cannot be maintained for long periods of time. More marked rebound effects are observed after the discontinuation of strict diets than after moderate dietary modifications. Two additional concerns regarding strict dietary limitations are: (1) the risk of not meeting basic nutrient requirements and thus adversely affecting growth; and (2) the risk of inducing adverse psychological effects, including appetite or eating disorders, feelings of stigmatization, anxiety and low self-esteem, especially if the intervention is not successful or the child has prior psychological problems (12, 13). Many questions regarding what constitutes the best treatment remain unanswered: there have been few sufficiently large multicentre clinical trials to test the efficacy and safety of well-defined obesity treatment programmes. Such trials may reveal which non-pharmacological and non-surgical interventions can help manage obesity over the long term. Losing weight over the short term, but then experiencing a rebound gain in weight, remains the usual experience for the majority of obese children and adolescents. The importance of further research cannot be over stated, but it is not uncommon for research and treatment to compete for limited financial resources, with research frequently being more successful in securing financial support. The lack of paediatric obesity clinics at many well-respected academic institutions illustrates this point. If the current approach to treatment is largely aimed at bringing the problem under control, rather than effecting a cure, and if this aim is only successful when a multi-disciplinary and intensive regimen is mounted, then managing the obesity epidemic will be vastly expensive and probably unaffordable for most countries. Pharmaceutical approaches may assist, but cannot replace, the multi-disciplinary management of obesity. Prevention is the only feasible option and is essential for all affected countries. Yet effective techniques for prevention have also proved elusive. Programmes to prevent obesity in children may start by identifying those children at greatest risk, but there are problems with this approach. Although screening for obesity potential may help target resources where they are most needed, such screening also creates stigma among the children identified if they are singled out for special attention. Furthermore, genetic studies suggest that most children are at risk of weight gain, and that strategies to prevent obesity in a child population – such as encouraging healthful diets and plentiful physical activity – will benefit the health of all children, whether at risk of obesity or not. The most logical settings for preventive interventions are school settings and home-based settings. A number of interventions have been tried at these levels, and these are reviewed in the present report, but success has been hard to demonstrate. A Cochrane review of those trials of sufficient duration to detect the effects of intervention concluded that there was little evidence of success (14). It suggested that a more reliable evidence base is needed in order to determine the most cost-effective and health promoting strategies that have sustainable results and can be generalized to other situations. As shown in the present report, there are several examples of interventions designed to prevent the rising levels of obesity – such as the school-based ‘Trim and Fit’ programme in Singapore and the ‘Agita Sao Paulo’ programme in Sao Paulo, Brazil. Favourable outcomes have been shown with small-scale interventions, modifying children's TV watching behaviour and promoting consumption of healthier foods by establishing a price differential. Although the beneficial results of such interventions may be detectable and significant, they are small compared with the size of the problem. Moreover, the improvements tend to decline after the intervention ends. It must be concluded that interventions at the family or school level will need to be matched by changes in the social and cultural context so that the benefits can be sustained and enhanced. Such prevention strategies will require a co-ordinated effort between the medical community, health administrators, teachers, parents, food producers and processors, retailers and caterers, advertisers and the media, recreation and sport planners, urban architects, city planners, politicians and legislators. This report highlights the underlying social changes that have led to rising levels of obesity in both the adult and child populations. These underlying factors, as listed below, are often a part of, or a consequence of social development and urbanization. Such development based on economic growth to enhance consumption is generally regarded in a positive light and, especially in developing countries as they emerge from poverty, may be aspired to. Increase in use of motorized transport, e.g. to school. Increase in traffic hazards for walkers and cyclists. Fall in opportunities for recreational physical activity. Increased sedentary recreation. Multiple TV channels around the clock. Greater quantities and variety of energy dense foods available. Rising levels of promotion and marketing of energy-dense foods. More frequent and widespread food purchasing opportunities. More use of restaurants and fast food stores. Larger portions of food offering better ‘value’ for money. Increased frequency of eating occasions. Rising use of soft drinks to replace water, e.g. in schools. Changes in these social trends may require increased awareness by countries of the health consequences of the pattern of consumption as the first step in a strategy to promote healthier diets and more active lives. Several authors 15-18) have suggested that efforts to prevent obesity should include measures involving a wide range of social actions, such as: public funding of quality physical education and sports facilities; the protection of open urban spaces, provision of safer pavements, parks, playgrounds and pedestrian zones, creation of more cycling paths; taxes on unhealthy foods and subsidies for the promotion of healthy, nutritious foods; dietary standards for school lunch programmes; elimination or displacement of soft drinks and confectionery from vending machines in schools and offering healthier choices (i.e. low-fat dairy products, fruits and vegetables); clear food labelling and controls on inconsistent health messages; controls on the political contributions given by the food industry; restrictions or bans on the advertising of foods to children; limits on other forms of marketing of foods to children; assessment of food industry initiatives to improve formulations and marketing strategies. It is clear from these suggestions that policies and actions will be needed at a variety of levels, some local and individually based, some national or internationally based. All of them will require the support and involvement of departments across the broad range of government and may include education, social and welfare services, environment and planning, transport, food production and marketing, advertising and media, and international trading and standard-setting bodies. Obesity prevention will involve work at all levels of the obesogenic environment. As Fig. 2illustrates, attempts to improve the environment at one level, for example the school, may be undermined by a failure to improve the environment at another level, be it below in the home, or above in the social and cultural context involving food marketing and advertising, lost recreational facilities or unsafe streets. The opportunities for influencing a child's environment. Children are vulnerable to the social and environmental pressures that raise the risk of obesity. Although they can be encouraged to increase their self-control in the face of temptation, and although they can be given knowledge and skills to help understand the context of their choices, children cannot be expected to bear the full burden of responsibility for preventing excess weight gain. The prevention of childhood obesity requires: improving the family’s ability to support a child in making changes, which in turn needs support from the school and community, for example . . . ensuring the school has health-promoting policies on diet and physical activity, and that peer group beliefs are helping the child, which in turn requires that . . . the cultural norms, skills and traditional practices transmitted by the school are conducive to health promotion, and that the community a environment, such as . . . policies for and and recreation and ensuring to food which in turn requires that . . . at and regional level are such e.g. for and improved food through and that . . . national and international that standards and services are encouraging better public and practices promote choices, which in turn may require . . . and support to ensure that strategies for obesity are and and control measures are and that these are not by other government and that . . . government and activities in all including education, transport, the environment and social welfare policies are for their health and food e.g. for for the and schools and other involved in public are with health and The present report is to health social and in a to at national and international level, by a to the problems and an of the policies needed to It is written in the context of the Health work on the prevention of chronic and the development of strategies to promote physical activity and The document (6) the development of with health with other and to develop relevant programmes and The document for positive such as measures to support the greater of nutrient dense to reduce on motorized transport, to increase to recreation facilities and to ensure health is and easily and health are relevant and The WHO has the restrictions on countries by international such as those that and marketing The WHO can a in public health when these This upon political which in part upon from the medical and from The present report is designed to to that The International Obesity upon the WHO to countries to develop Obesity and to childhood obesity prevention within those of might be clear and e.g. on food food to more nutritious foods for children; develop for advertising that healthier improve and of facilities and local schools to and physical activity medical and health professionals to in the development of public health programmes. The International Obesity is to the WHO in developing these childhood obesity will require and but the world's children no suggest that of body fat should be in its of body with small measurement in of and of to the and with further that all these of in children and adolescents in a range of using a range of In this both and methods for assessing and are described and the and of these different methods used for population and clinical are measures of body an of body fat and of Such techniques include or and energy The methods are used for research and in care but may be used as a to measures of body the measures of or are and other and from and weight such as or the and All to some on the of the and their as a of must be a of The primary for overweight and obesity are to health and to between populations. with a need to be that where should that best these For the have been based on with and BMI being the most used both and in population Although not health weight for have a of assessing populations of children, especially those aged under years, and are used to both and weight for is and low weight for is found as a consequence of disease. A high weight for is overweight and high weight for is The use of weight for has the of not requiring knowledge of the child's which may be hard to in less developed but it should not be used as a for for or weight for as all measures different in In the use of weight for was recommended by WHO for children below the of 10 years, but a WHO review found that use of the for Health should not be recommended especially as it not account of between and children The WHO may consider standards based on studies of children showing growth The weight for is on a based on a which a based on the between the observed and the of a standardized the of the population. a of is to the or a of is to the and a of is The use of a weight for allows a more of an or a and between populations can also be and trends over time can be the in an require skills or programmes. In of overweight and obese the are based only on rather than a health In a study of young people aged 5–17 years, that fat as by was associated with an adverse and A high has also been shown to Although have been described for the for high or low health have not been may be in clinical as a of a child or to weight control In it may be used to a population in of fat and to determine the prevalence of risk cannot be used to a child as being at a high or low As suggested in 2 BMI is significantly associated with in childhood and and is the most of BMI with and It during the first after after the first and around the of this second is sometimes referred to as examples of childhood BMI by and A given of BMI needs to be and Several countries, including the and the have developed their using local In the USA, by from in the early have been used and were recommended for children years or by a WHO in More the for Health has based on from national health from although to an of the weight and BMI from the most were for children over the of years The of using is that a child can be described as being above or below certain (for example the or which can be in a clinical are from a single and an as overweight or obese that the is to that population. Furthermore, may the as an when the may in from a population with a high prevalence of obesity, such as the USA The that those children with a BMI greater than or to the be as and those children with a BMI between the and be as risk of In some children at or above the are referred to as and in to children above the As with the use of measures compared with populations, BMI can be compared with a and reported as A BMI is