Almost a third of children in the UK are now overweight

The National Institute for health and Clinical Excellence has developed guidance for preventing and treating obesity in adults and children.

Most of the draft document focuses on how to prevent adults and children becoming overweight.

Obesity experts said surgery was a "last measure" but could be necessary.

Surgery can be the only option left Dr Ian Campbell, obesity specialist

Current estimates suggest just under a third of those under 16 are overweight and 17% of those people are obese.

NICE will issue the guidance on Thursday for consultation.

It says children at or near "physiologic maturity" could be considered for stomach surgery.

The term usually describes development by the age of 18 - but as children develop earlier experts say they can reach this point at around 16.

'Only option'

NICE said it planned to recommend drugs and surgery for children only when they had reached a similar level of risk to their own health because of their weight as obese adults.

It also suggests that drug treatment can be considered for children with a weight problem if they are aged 12 or over, and only been given by specialists.

Dr Ian Campbell, an obesity specialist in Nottingham, said surgery and medication had to be considered for some children.

"There are more children who have exhausted all treatment options and who are suffering from uncontrollable diabetes or at risk of heart failure because of their obesity.

"Surgery can be the only option left."

He said that, in the last 12 months, he had heard of one child in Sheffield and another in Glasgow having stomach surgery.

Dr Campbell added: "There is no suggestion surgery should be a commonplace procedure.

"Surgery - and drug treatment - would only be used when all other measures were exhausted.

Key parental role

Much of the NICE document looks at preventative measures.

Parents are key to ensuring children are healthy, and NHS staff are asked to stress the importance of eating together and families being as active as possible.

But NICE says schools are also crucial in ensuring children do not become overweight or obese.

Nurseries are urged to minimise the amount of time small children are sedentary, and urged to provide structured physical activity.

For older children, schools are asked to assess the impact of all school policies on health, including building layout and vending machine policies.