Obesity is a global challenge for healthy populations. It has given rise to a wide range of public health interventions, focusing on supportive environments and lifestyle change, including diet, physical activity and behavioural change initiatives. Impact is variable. However, more evidence is slowly becoming available and is being used to develop new interventions. In a period of austerity, momentum is building to review these initiatives and understand what they do, how they do it and how they fit together. Our project seeks to develop a relatively straight forward systematic framework using readily accessible data to map the complex web of initiatives at a policy, population, group and individual level aiming to promote healthy lifestyles, diet and physical activity levels or to reduce obesity through medical treatments in a city or municipality population. It produces a system for classifying different types of interventions into groupings which will enable commissioners to assess the scope and distribution of interventions and make a judgement about gaps in provision and the likely impact on mean body mass index (BMI) as a proxy measure for health. Estimated impact in each level or type of intervention is based upon a summary of the scientific evidence of clinical and/or cost effectiveness. Finally it seeks, where possible, to quantify the potential effects of different types of interventions on BMI and produce a cost per unit of BMI reduced. This approach is less sophisticated but identifies the areas where more sophisticated evaluation would add value.