Britain is in the grip of an epidemic. Almost two thirds of adults and a third of children are either overweight or obese, and work by the Government Office for Science’s Foresight2 programme suggests that, without clear action, these figures will rise to almost nine in ten adults and two-thirds of children by 2050. This matters because of the severe impact being overweight or obese can have on an individual’s health – both are associated with an increasing risk of diabetes, cancer, and heart and liver disease among others – and the risks get worse the more overweight people become. They matter because of the pressure such illnesses put on families, the NHS and society more broadly, with overall costs to society forecast to reach £50 billion per year by 2050 on current trends.

At the core of the problem is an imbalance between ‘energy in’ – what is consumed through eating – and ‘energy out’ – what is used by the body, including energy used through physical activity. While individual responsibility for decisions about energy consumption and expenditure is important, recent work by Foresight and others shows that a multitude of factors can affect these decisions. Genetic, psychological, cultural and behavioural factors all have an important role to play and these are difficult to influence. Foresight showed that the changing pattern of our lives, which equally affects food consumption and physical activity, makes it increasingly hard for people to maintain a healthy weight. From the nature of the food that we eat, to the built environment, to the way our children lead their lives, modern life is making it harder for all of us to fulfil our goal of staying healthy and well.