There's the park, now go and get fit

Lazy Londoners will be handed a map of their local park to encourage them to get fit.

This is part of a raft of measures to be unveiled tomorrow by ministers in a new crackdown on obesity.

GPs will also measure the physical exercise levels every three and six months of "couch potatoes" who are at risk of high blood pressure and diabetes.

The programme is being rolled out in eight GP surgeries across five London primary care trusts including Islington, Wandsworth and Haringey.

It is backed by Natural England, an environmental organisation, NHS London and Sport England.

This comes as the Government is under attack for failing to halt obesity, especially in children.

Health experts will warn next week that the lives of obese people and teenagers are at risk because they are not being monitored properly.

On Monday, the National Obesity Forum (NOF), which raises awareness about weight-related health issues, will call for a special register to be set up listing all overweight children in Britain and for doctors to offer obesity cessation classes which already exist for smokers.

Dr David Haslam, chair of the NOF, told the Evening Standard that obesity is a 'health time-bomb.'

He said: "Obese people die 10 years early and they also put an enormous burden on the NHS. Unless doctors are given greater incentives to monitor patients then the situation will only get worse."

The cost to the NHS of health problems such as high blood pressure and diabetes, which are associated with a lack of exercise, is estimated at £1.7 billion a year. Rates of obesity have also soared among teenagers and children with as many as 22 per cent of girls and 19 per cent of boys aged two to 15 now classed as overweight.

Officials had set a deadline of 2010 for tackling obesity in children but the Evening Standard has learned that this deadline has been quietly ditched.

New guidance slipped out by the Treasury this week recommends the original target be delayed by a decade - until 2020.

Ministers will face renewed pressure to tackle Britain's fat issue when a panel of top advisors publishes its findings on the nation's fat problem on Wednesday.

Foresight, whose members include top scientists and clinicians, is expected to reveal that the number of overweight adults is going to treble and that the figure will double for boys over the next forty years unless urgent action is taken. It will present a worrying picture of how eating junk food and not exercising is leading to premature death.

Their five key messages for policymakers are expected to include the fact that forcing people to lose weight does not work and that fast food manufacturers like McDonalds and Burger King must take more responsibility for influencing the nation's eating habits.