A ‘‘talking plate‘’ which tells diners how quickly to eat their food is to be used by the NHS to tackle obesity.

The Swedish-made £1,500 Mandometer, uses a scale which measures how quickly food is leaving the plate and barks out phrases such as “please eat more slowly” if it finds that food is being consumed too fast.

NHS bosses are to trial the revolutionary technology in a study to see if it can change the dietary habits of overweight families.

Health experts claim that making people eat more slowly helps train them to eat less – as they are more likely to feel full.

The study, run by Bristol University with the help of NHS GPs and nurses, will involve 600 families, each with an obese parent and an obese child.

Per Sodersen, a founder of the Swedish company which invented the Mandometer, said: ‘‘Telling an obese person to diet will not work because dieting slows down the metabolism in preparation for starvation. What is more important is the speed at which you eat and to recognise when you are full so you eat less.”