Implications of the Foresight Obesity System Map for Solutions to Childhood Obesity

Abstract

Shifting the paradigm Our understanding of the causal factors that contribute to the obesity epidemic has evolved over time. Although some still describe the problem as "people eat too much and move too little," this articulation has not brought us closer to understanding what to do to reverse current trends. Various conceptual models have framed the problem of obesity in different ways. Bray suggested an epidemiological model which illustrates agents such as food, viruses, and toxins acting on a host to produce disease, and a homeostatic model where fat acts on the brain (controller) which in turn feeds back to act on the fat (controlled system) ((1)). He described the interpretation of these models as "genetic background loads the gun, but the environment pulls the trigger" and suggested they imply the need for a simple FLOURIDE (For Lowering Universal Obesity Rates Implement ideas that Don't demand Effort) solution. The International Obesity Task Force expanded on the concept of environmental agents by introducing its "causal web" ((2)). In the causal web, environmental factors are illustrated as "black boxes" such as school food and activity, public transport and urbanization. These factors are organized in columns according to their proximity to the individual, i.e., factors associated with work/school/home, community/locality, national/regional, and international levels. Distal contextual factors such as globalization of markets, and media and culture are shown to act on more proximal factors which in turn act on energy expenditure and food intake. The connections are simple one way arrows and biological factors are not included. The causal web helps to illustrate the diversity of factors affecting individuals and suggests that we will need to implement many ideas that "don't demand effort" on the part of the individual. Although the causal web suggests the challenge of addressing obesity is complicated, it does not explicitly illustrate the problem as "complex". Absent from the causal web is consideration of the feedback loops which are a hallmark of complex adaptive systems. More recently the Foresight Programme of the UK Government Office for Science published an obesity system map, developed through a multistakeholder process ((3)). This qualitative, conceptual model has 108 variables, some of which are measureable (e.g., the ambient temperature of the indoor environment), and other variables that are more difficult to quantify (e.g., desire to differentiate food offerings). The relationships between the variables are illustrated with >300 solid or dashed lines to indicate positive and negative influences. All the variables are interconnected, some with large numbers of inputs and others with large numbers of outputs. The connections give rise to feedback loops with as few as two variables (e.g., a affects b which in turn affects a) or involving as many as 16 variables. At the core of the map is "energy balance" (energy intake vs. energy expenditure). The core (also referred to as the engine) is surrounded by variables that directly or indirectly influence energy balance. These variables are clustered in seven themes ranging from Food Production to Physiology. Apart from the physiological cluster, most of the variables can be considered on an individual, family, group, or societal scale. For example, the "level of physical activity" can be considered for a particular individual or as an average for the whole population. The Foresight obesity project articulated the ambitious goal of defining the obesity system as "the sum of all the relevant factors and their interdependencies that determine the condition of obesity for an individual or a group of people" ((3)). Although the notion that the process could give rise to a map of "all" relevant factors was perhaps over ambitious, the map effectively illustrates the complexity of obesity by highlighting the interdependencies among variables as diverse as the pressure on the food industry to cater for acquired tastes and conscious control of an individual's accumulation of energy. The map is dominated by its illustration of the connections and feedback loops between variables. Although the map cannot be considered comprehensive, its construction engaged a broad range of stakeholders, including scientists, the private sector and government departments in a dialogue about how to tackle this wicked problem ((4)). The dialogue helped to forge multisector, multidisciplinary relationships that support future government decision making based on evidence ((4)). An enduring value of the map is its use as a heuristic. It illustrates the complex multifactoral nature of the systems that give rise to obesity and it can be used to stimulate an even broader discussion among relevant actors ranging from multiple government departments to school age children ((5),(6)). In this way the map helps the development of a more sophisticated and integrated policy approach. The