James Cracknell, the athlete turned anti-obesity campaigner, was the subject of sniggering and derision in April when he said that North Korea and Cuba had got a ‘handle on obesity’. With impressive understatement, he attributed this to both countries being ‘quite controlling on behavioural trends’. It was a bad point poorly made, but in a roundabout way he drew attention to the major obstacles faced by those who want to reduce obesity rates in the rest of the world: freedom and affluence.