Ken Snider, who advises the National Institute for Health and Clinical Excellence (NICE), said that tackling extreme fatness was not only about weight loss but also preventing obesity in the first place.

NICE said that in “a handful of cases” a year radical surgery to reduce the stomach size by gastric banding, and thereby control food intake, may be justified. But the technique — bariatric surgery — would be used only in those who were physically mature and had a body mass index of 40 or more, the guidelines say.

For adults with a BMI of 50 or more, surgery should be considered as a first-line option, and a “few thousand” such operations might be taking place every year within a few years, said Professor John Wilding, who runs an obesity clinic at University Hospital Aintree, and was one of the team responsible for drafting the guidance.

He admitted that suggesting bariatric operations for children was highly controversial. “But it is right that the NHS is given the go-ahead to take radical action when faced with such a major threat to the health of our children.”

Mr Snider, who is also a public health physician in Co Durham, said that obesity was more harmful to health than smoking, heavy drinking or poverty. “Tackling the obesity epidemic isn’t just about treating people who are already obese, it’s also about helping people to avoid becoming overweight in the first place,” he said. “We are recommending action by individuals, schools, local authorities, urban planners and employers to make it easy for us all to be physically active.”

Nurseries and childcare groups are urged to increase active playtime while schools are encouraged to develop an ethos that “helps children and young people to maintain a healthy weight, eat a healthy diet and be physically active”.

For children who are already overweight or obese, the guidance tells health workers to assess lifestyle, willingness to change and factors that could be contributing to weight gain, such as low self-esteem, bullying and a family history of weight problems.

Children should “take a total of 60 minutes of at least moderate activity each day, in one session or several shorter ones lasting ten minutes or more”, and overweight children may need to take more.

The weight-loss drugs Xenical (orlistat) or Reductil (sibutramine) should only be considered for use in children after “dietary, exercise and behavioural approaches have been started and evaluated”.

For children aged 12 and over, drug treatment is recommended only if there are related physical illnesses such as orthopaedic problems or “severe psychological” issues.

Surgical interventions such as gastric banding should be offered only if a child has “achieved or nearly achieved physiological maturity” — defined by NICE as having gone through puberty — and other methods of weight loss must also have failed to produce results for at least six months before surgery is offered.

Professor Peter Littlejohns, clinical and public health director at NICE and executive lead for the guidance, said: “For the first time we have brought together all the people that can help solve the obesity problem — not just health professionals, but also local councils, employers and schools.”

£7.4bn is the cost of obesity to the economy each year. It is linked to the two leading killers, cardiovascular disease and cancer, and shortens lifeby seven years. One in three children aged 2 to 15 is classed as overweight or obese. Half of those will become obese adults

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Donor organ allowed child’s own heart to heal
• Michael Jackson: Not the final chapter
• Sacha Baron Cohen forced to tone down Brüno