Britain's couch potato lifestyle means that by 2030, the average person will use just 25 per cent more energy than if they had stayed in bed all day, a report has warned.
Public health experts said sedentary habits in this country are responsible for 17 per cent of premature deaths, with an impact on health that costs the economy more than £8bn a year.
The study based on local authority data found that in some parts of the country, four in ten people are taking less than half an hour’s exercise a month. Manchester fared worst, followed by Sandwell, West Midlands, Salford, Greater Manchester and Bradford, in West Yorkshire.
Even in the fittest areas - Wokingham in Berkshire, and the London Borough of Richmond-upon-Thames - one in five person did not manage 30 minutes of activity .
The target could be achieved by carrying out three ten-minute bursts of ‘moderate intensity’ activity, spread across four weeks.
UK Active, a not-for-profit health organisation, said Britain’s lifestyle has deteriorated so badly that in less than a decade, activity levels will be just one quarter higher than if the average person stayed in bed all day.
Overall one in four adults - 12.5 million people - was classed as inactive - meaning that they had not done at least thirty minutes of moderate intensity physical activity, according to the analysis by UK Active.
Such lifestyles shorten life expectancy by an average of five years, experts said.