A group of 13 and 14-year-old students were shown a news story which claimed adults who controlled large food corporations spent billions on marketing to coerce them into eating fatty foods, The Times reported.

Teens hit back against this ‘manipulation’ – and their canteen choices improved significantly. The biggest effects were in boys, who cut purchases of unhealthy food by roughly a third.

Christopher Bryan, of Chicago University, said: ‘Food marketing is deliberately designed to create positive emotional associations with junk food.

‘What we’ve done is turn that around by exposing their manipulation to teenagers, triggering their natural strong aversion to being controlled by adults.’