Food fads - healthy heating or pseudo-scientific nonsense?

A new book by the self-styled "Angry Chef," Anthony Warner, argues that much of what passes for healthy or "clean" eating is essentially codswallop - at best an indulgence in food fad-ism, at worst, a risk to people's real medical welfare. The BBC's Paul Moss saw him speak at the Port Eliot Festival, where there were plenty of healthy eaters on hand to challenge his views.