Why did obesity become a global problem? Professor of Diet and Population Health Susan Jebb explores a heavy history, our changing relationship with food and reasons for optimism. She believes we live in an 'ultra-processed food system' which drives more of the world's population towards health harming diets and a lifetime of being overweight or obese. But she also believes change is possible, and the conditions are right for a food systems change.

Also featuring Hannah Ritchie of Our World in Data, Henry Dimbleby, author of the 2020 National Food Strategy, and Alicia Weston of Bags of Taste, a programme of change for people with few cooking skills on low incomes.

Produced and presented by Dan Saladino.