With Britain becoming the fattest nation in Europe, Panorama travels to Denmark, the first country in the world to implement a tax on junk food, to see whether or not it is helping to cut obesity. The programme also visits the US, where a proposal to tax sugary drinks has met with fierce opposition. Reporter Shelley Jofre puts the idea of a 'fat tax' to the Health Secretary, and to families who would have to pay more for junk food.