"If somebody falls off a boat into the water and they can't swim and they drown, nobody says 'it's your fault, you should have held your breath'."

Is it wrong to be blunt about obesity?

Nick Finer, honorary clinical professor at University College London, said it was seen by many as "legitimate" to blame people for being overweight, but this ignored the role of the food environment around us.

He said: "If somebody falls off a boat into the water and they can't swim and they drown, nobody says 'it's your fault, you should have held your breath'.

"They happen to be in an environment where it's very easy to drown. We're in an environment now where it's very easy to over-acquire calories and energy."