Has Sadiq Khan’s junk food ad ban really stopped London getting fatter?

London Mayor Sadiq Khan made a bold claim this week: ‘As a result of our junk food advertising ban on Transport for London, nearly 100,000 cases of obesity have been prevented since 2019.’ Hailing the ‘incredible result’, Khan said ‘it’s expected to save the NHS over £200 million’. Is it true though?

To ascertain whether the ban worked, researchers from Sheffield university and the London School of Hygiene and Tropical Medicine produced a graph.