* based on literature collected for Eurocadet obesity prevention review

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There has been scarcely any systematic research into the effectiveness of preventive interventions used in accordance with modern views on health promotion. The latter dictate that interventions be attuned to the specific behavioural determinants and environmental factors which underpin high-risk behaviour, and that interventions in the field of information provision and education be combined with regulations and environmental factors.[1] Educational approaches that have been tried to address the obesity problem have not been very successful to date. This may be of inherent weaknesses in an education message that essentially tries to convince people that giving up things they really like is good for them. Inadequate funding for nutrition education may also be a problem given the much larger expenditure on food advertising by the industry. More attention needs to be given to the environmental aspects of the obesity epidemic. Environmental changes that would affect basic features of the food supply like availability and price would clearly affect many segments of society and would need broad support and consensus to be acted upon.[2]
The environments external to individuals have powerful effects on behaviours. The term ‘obesogenic environments’ is defined as ‘the sum of influences that the surroundings, opportunities or conditions of life have on promoting obesity in individuals or populations’.[3] It is broader than just the physical environment and includes costs, laws, policies, social and cultural attitudes, and values. The key role of environmental change is ‘to make the healthy choices easy choices’. In table 1 some of the key strengths of an environmental/systems-based approach underpinning obesity prevention efforts.

Table 1. Strengths of an environments/systems-based approach to underpin obesity prevention efforts (Swinburn & Egger, 2002).

Strengths	Examples
Addresses underlying causes	Parental fears for children’s safety as the major reason for driving children to school – addressing the substance and perceptions related to the fears is likely to results in more active transport to school
Becomes structural/systemic	Changing the physical environment for recreation, food laws, local government transport policies, etc., embeds the changes into the system
Becomes the accepted norm	Regular availability of reduced-fat milk, salad options, vegetable-based dishes, etc., helps to make them normative choices, just as smoke-free indoor environments helps to make non-smoking the norm
Likely to be sustained	Systemic changes such as safe, attractive cycle networks or health school-food menus, which are backed by strong policies and traditions, are more likely than media campaigns to sustain behaviours over  the long term
Influences the ‘hard-to-reach’	Disadvantaged populations, such as those with low income or low educational attainment, tend not to respond to health messages but they can still benefit from the fast-food outlet which cooks lower-fat French fries
Less language dependent	Health messages and information are often aimed at a narrow population segment and are often not transmitted in the native tongue of ethnic minorities, but all can take advantage of public transport
Can address inequities	Environmental interventions can not only reach populations with poor health outcomes but they can be differentially targeted to them, such as improving bus services, school food programs and active recreation amenities in poorer areas
Usually cost-effective	Environmental interventions (especially policy-based initiatives) are relatively inexpensive compared to individual-based approaches and media-based public education campaigns, and even the expensive strategies (e.g. improving public transport) are often cost-effective in the long term
Changes ‘default’ behaviour	Some food choices are highly influenced by price, labeling and availability, and changing these factors shifts the ‘default’ food choices
Minimizes message distortion	Education messages related to obesity (or foods that might promote weight loss) may be misconstrued or misapplied, and this risk is minimized by a greater emphasis on providing and promoting health choices rather than preaching about unhealthy choices

 

 

 

 

 

 

 

 

 

 

 

 

 

Food and physical activity environments can be influenced in several settings and sectors: for example school and other educational settings, home environments, neighbourhoods, primary care settings, workplaces, sports venues, transport and infra-structure sector, and the food-sector (including fiscal food policies, nutrition information panels, nutrition ‘signposting’ programmes, regulation of health and nutrition claims, advertising bans on children’s TV, and promotion of healthy eating and physical activity guidelines and messages).[3]
To reduce the healthy burden of obesity in a population, a spectrum of objectives may be acceptable for certain groups in particular circumstances. For some, an appropriate objective may be obesity prevention, for others weight loss, while for others weight maintenance and the management of co-morbidities. The appropriateness of the objective will depend upon the population’s age, weight and weight loss history, current co-morbidities, and level of motivation for change. Target populations should be selected according to risk for the development of obesity, as well as the feasibility, effectiveness, and ideally, cost-effectiveness of proposed interventions in that group. Life stages during which the risk for development of obesity is high include: prenatal period, the period of ‘adiposity rebound’ (5-7 years), adolescence, early adulthood (18-30 years), pregnancy/post-partum, and menopause. Similarly, certain population subgroups are at high risk for the development of obesity: genetically susceptible individuals with a strong family history of obesity, certain ethnic groups, lower socio-economic groups, and individuals who have recently quit smoking, lost weight, or are taking certain medications such as corticosteroids and beta-blockers.[4]

Many countries and research funding agencies seem to show a strong tendency to develop interventions for children and adolescents exclusively. It can be easily shown, however, that intervention programmes are much more likely to be cost-effective in older adults than in children, for the following reasons:

1. the sharpest increase in the incidence of obesity is in adulthood;
2. adults usually continue to gain weight during adulthood (particularly in young adulthood);
3. adult weight gain is (independently of the extent of overweight) a risk factor for many disease such as heart disease, type 2 diabetes mellitus and breast cancer, and all-cause and CHD mortality;
4. although for many disease the relative risks for disease associated with obesity decrease with age, the absolute and population-attributable risks for disease increase with age;
5. prevention of weight gain and weight loss in adults have been shown to be related to dramatically-reduced relative risks for, for example, type 2 diabetes mellitus in high-risk populations. Weight gain prevention may be of particular importance in those who are already overweight, since the relationship between BMI and risk of type 2 diabetes increases exponentially;
6. interventions in children and adolescents need to be maintained for many more years or decades in order to have a considerable effect on the number of new cases of type 2 diabetes mellitus and heart disease or cancer compared with interventions in older individuals;
7. if interventions for weight gain prevention are directed at young and older adults by supporting healthier diets and physical activity it is likely that other members of the household will also be affected.
   This indicates that adults should not be neglected as target populations for obesity prevention.[5, 6]

Although societal-level interventions may take a long time to put into place, and even longer to yield results, they can begin to counteract the powerful forces that lead to steady population weight gain. Some key issues for societal level solutions are:[7]

• Food and nutrition policy initiatives must be central to societal solutions for obesity prevention, but will not suffice on their own.
• Physical activity policy initiatives are also essential and may be motivated by fields other than health, e.g. sustainable transport, family recreation.
• Links are needed between policies and processes in different sectors and social structural levels.
• The types of initiatives needed to shift policies and process towards the promotion of health population diets, activity levels and weight status will differ culturally and between and within countries.
• Societal approaches must also emphasize increasing options and removing barriers to healthy living among those who are the least advantaged.

Furthermore, there are 10 principles upon which efforts to prevent obesity at the population level should be based:[7]

1. Education alone is not sufficient to change weight-related behaviours. Environmental and societal intervention is also required to promote and support behaviour change.
2. Action must be taken to integrate physical activity into daily life, not just to increase leisure time exercise.
3. Sustainability of programmes is crucial to enable positive change in diet, activity and obesity levels over time.
4. Political support, intersectoral collaboration and community participation are essential for success.
5. Acting locally, even in national initiatives, allows programmes to be tailored to meet real needs, expectations and opportunities.
6. All parts of the community must be reached – not just the motivated healthy.
7. Programmes must be adequately resourced.
8. Where appropriate, programmes should be integrated into existing initiatives.
9. Programmes should build on existing theory and evidence.
10. Programmes should be properly monitored, evaluated and documented. This is important for dissemination and transfer of experiences.

Reliance on obesity treatment approaches, even if fully effective, is neither practical nor desirable. The burden of obesity in the population, particularly when certain high-risk and currently underserved populations are considered, is likely to exceed the capacity of the health care delivery system to deliver such treatment either for obesity itself or for the associated conditions. Furthermore, obesity treatment cannot necessarily remove or reverse the adverse effects of obesity on health status and quality of life, particularly for obesity of long duration. Although effective interventions for obesity prevention may share some similarities with those used for weight loss, the science of obesity prevention – which includes identification of those aspects that are unique to prevention compared to treatment – is only now emerging. Relatively little research has thus far focused on obesity prevention. Some key issues and challenges:[8]

• More incentives for both recruitment and attendance may be needed for obesity prevention programs compared to programs in which the outcome (weight loss) is itself more motivating;
• Because not all participants in preventive interventions may need to lose weight and because preventive behaviors must be maintained indefinitely, the messages in obesity prevention programs should focus on food intake and physical activity behaviors that can be recommended for permanent adoption.
• The ability to counsel for balancing day-to-day energy intake and output is much more challenging than counseling to create an energy deficit, particularly given the difficulty of accurate self-assessment of whether one is on track for making the small reductions.
• Several complementary strategies may be useful in making an effective transition to maintenance, including a gradual increase in caloric intake goals to the level appropriate for maintenance, continuing the use of meal replacements, maintaining a tapering frequency of contact through various media (e.g., group meetings, individual counseling, telephone, mail, and internet), and training some participants for leadership roles as peer group leaders or mentors.

Prevention research is more applied and more interdisciplinary than treatment-oriented research, including nutrition education and communications, public health practice, exercise physiology, physiology of aging, dietetics, nutritional epidemiology, minority health, maternal and child nutrition, and psychology and other social and behavioral sciences. Both scientifically and practically, obesity prevention research cannot be viewed simply as an extension of obesity treatment but also, and perhaps primarily, as a type of prevention research.[8]

In May 2004, six of the - at that time - 15 EU member states have an operational nutrition policy (UK, the Netherlands, Finland, Denmark, France, Sweden). The available nutrition action plans generally seem to comply with international recommendations, although large variations are observed between the member states in terms of terminology, nutritional recommendations (for example in case of reduction of simple sugars), institutional framework, nutritional scope, social groups targeted, and monitoring and evaluation structures.[9] A Green Paper called “Promoting healthy diets and physical activity: a European dimension for the prevention of overweight, obesity and chronic diseases” was released in December 2005 by the Commission of the European Communities. The Commission services will carefully analyze all contributions received in reply to the consultation process launched by the Green paper. It was expected that a report summarizing the contributions will be published on the Commission’s website by June 2006 (not available to date (VL, July 2006)).
 
References

1. Kemper HC, Stasse-Wolthuis M, Bosman W. The prevention and treatment of overweight and obesity. Summary of the advisory report by the Health Council of The Netherlands. Neth J Med 2004; 62: 10-17.
2. Jeffery RW. Public health strategies for obesity treatment and prevention. 2001; 25: 252-259.
3. Swinburn B, Egger G. Preventive strategies against weight gain and obesity. Obes Rev 2002; 3: 289-301.
4. Reeder BA. National and international strategies to prevent obesity and diabetes. Adv Exp Med Biol 2001; 498: 393-400.
5. Gill T. Importance of preventing weight gain in adulthood. 2002; 11: S632-S636.
6. Seidell JC, Nooyens AJ, Visscher TL. Cost-effective measures to prevent obesity: epidemiological basis and appropriate target groups. Proc Nutr Soc 2005; 64: 1-5.
7. Kumanyika S, Jeffery RW, Morabia A et al. Obesity prevention: the case for action. 2002; 26: 425-436.
8. Kumanyika SK, Obarzanek E. Pathways to obesity prevention: report of a National Institutes of Health workshop. Obes Res 2003; 11: 1263-1274.
9. Lachat C, Van Camp J, De Henauw S et al. A concise overview of national nutrition action plans in the European Union Member States. 2005; 8: 266-274.