Parents of 5-year-olds are to be sent official warning letters if their child is found to be obese, as part of a national programme to weigh children in schools.

Ministers are bracing themselves for charges that they will stigmatise fat children when they publish proposals next month to tackle rising levels of obesity, The Times has learnt.

Alan Johnson, the Health Secretary, is understood to have been persuaded that it is in children’s best interest if their weight is brought formally to the attention of their parents.

The routine weighing of primary school pupils was reintroduced in England and Wales two years ago in response to obesity fears. The National Child Measurement programme aims to collect data on every child twice, when they start school and when they leave. Parents of 5 and 10-year-olds can request the measurements but are not informed automatically, even if the child is severely overweight.

Ministers resisted the plan of warning letters last year, amid fears that they would cause a boycott of the scheme, the main purpose of which is supposed to be to identify national and regional trends.

The weighing programme was criticised after its first year when ministers admitted that participation levels had been so low that the statistics were all but useless.

Rates for the past year, however, are much improved, with measurements for almost a million children collected and every primary care trust in England and Wales taking part. From the next school year parents will be encouraged to request measurements and will be directed to a new website helping them to calculate how much their children should weigh.

Mr Johnson is preparing to go farther and insist that all parents are sent the information as a matter of course. He toughened his stance last week in a Commons statement on a report that gave warning that 60 per cent of men, 50 per cent of women and 26 per cent of children and young people would be obese by 2050, based on current trends.

The Foresight report laid bare the life-threatening consequences for children growing up fat, predicting a 70 per cent rise in type 2 diabetes, 30 per cent in strokes and a 20 per cent rise in coronary disease. The heightened risk of such conditions is estimated to reduce life expectancy by as much as 13 years.

A recent report by the Commons Health Select Committee went even further, suggesting that a generation of children would die before their parents if obesity was not addressed. The report envisaged a doomsday scenario where thousands would lose limbs and sight.

Mr Johnson said that children would continue to be the focus the national obesity plan when he announced it last week. “More than 80 per cent of obese 10 to 14-year-olds remain obese into adulthood,” he said.

Professor Sir Albert Aynsley-Green, the independent advocate for children, said last year that telling parents their children were too fat “risks stigmatising those who are overweight”.

But in a sign of shifting attitudes, the Office of the Children’s Commissioner said last night that obesity was rising so fast it would give the measure a cautious welcome.

Claire Phillips, its policy director, said: “Our concern is that parents are given help in the form of a package of support to help them make the necessary changes to lifestyle.”

A Department of Health spokesman said: “The programme is a vital part of engaging with children and families about healthy lifestyles and weight issues. We need to take this farther and help parents to understand the importance of healthy weight for their family.”

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