Children as young as 12 could be given anti-obesity drugs and stomach-stapling surgery as part of a package to tackle the obesity epidemic, according to official guidelines issued today.

In the first comprehensive review of the obesity problem, the government's health watchdog also recommends that the most severely overweight adults should be offered surgery as a first line of treatment, despite it costing around £10,000 a patient. Plastic surgery to take away excess skin after weight loss will also be offered. Hundreds of adults a year will be operated on initially with thousands a year expected in the near future.

The report from the National Institute for Health and Clinical Excellence (NICE) includes recommendations to parents, teachers, local authorities and employers.

It follows a Department of Health report, published in August, that showed a third of all adults and a fifth of all children under 15 will be clinically obese by 2010. More than 12 million adults and a million children are expected to be obese - with several million more being overweight.

The recommendations have been welcomed by the Department of Health, the National Obesity Forum, and the Royal College of General Practitioners.

But the BMA warned that more resources would be needed to finance the measures, expected to cost £63m in the first year, and £40m in successive years - though long-term savings of £20m a year are expected within a decade. The NHS, facing deficits of £1.2bn, has been given no additional funding to tackle the issue.

GPs questioned how they could fund enough practice nurses to ensure patients were given up to 15 sessions a year to guide them through weight loss programmes. "The physical resources aren't there to offer this level of support. This is an aspirational guideline," said Professor Paul Little, a practising GP and researcher. "GPs will say: 'Tell me what am I doing at the moment that you want me to stop doing so that I can do this?'"

The guidelines, which took two years to produce, urges employers to provide showers at work and cycle racks and subsidise gym membership. Local authorities are advised to provide more cycle lanes and traffic calming schemes and to build more safe exercise areas. Teachers are told to eat with young children. Nurseries are told to make sure children do little play activity that is sedentary.

But, for the most obese adults and children, exercise and diet will be insufficient - hence the recommendation that children be given anti-obesity drugs - even though they are unlicensed for their use, and not currently recommended for children - and in extreme cases, surgery.

The drugs, Reductil, an appetite suppressant, and Xenical (orlistat), which inhibits the absorption of fat, cost £50 and £40 a month and have side-effects including gastronintestinal problems and, for Reductil, hypertension and palpitations.

For these reasons, NICE says the drugs should only be prescribed to children under 12 "in exceptional circumstances".

Surgery, such as gastric banding, stomach-stapling or stomach bypass - all of which restrict the size of the stomach - should also only be offered "in exceptional circumstances". Young patients must undergo psychological assessment and will only be operated on if all other methods of weight loss have failed to have an effect for at least six months.

NICE estimates that only a few children a year will receive this treatment but insist it is justified. Professor John Wilding, professor of medicine at the University of Liverpool and a committee member, said: "Some of the treatment options we are recommending in this guideline such as offering anti-obesity drugs and surgery to children will be seen as 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."

Professor Jim McEwen, emeritus professor in public health at Glasgow University, who chaired the committee, said it had been right to be ambitious in its guidance because of the severity of the problem. Obesity is linked to the two major killers, cardiovascular disease and cancer. It shortens life by seven years and costs the economy £7.4bn a year.

The Department of Health - which is likely to miss its target of halving child obesity by 2010 - welcomed the recommendations, which will be sent to every GP, school, local authority, employer and town planner. Public health minister Caroline Flint said the government would consider the guidance closely.

Guidelines

Adults

· Should follow diets aimed at losing no more than 0.5-1kg a week, and only use low calorie diets of less than 1,000 a day for 12 weeks at most

· Should do at least 30 minutes of moderate-intensity physical exercise, five times a week

· Should be offered surgery as a first-line option if their BMI is 50 or above, and as last resort if patients have a BMI of above 40 and have failed to maintain weight loss for at least six months. Plastic surgery following weight loss will be permitted

Children

· Can be offered surgery if their BMI is 40 and above, or 35 and above with other risk factors such as diabetes or high blood pressure, and they have gone through puberty

· Can be given sibutramine or orlisat but only if there are other physical problems and once diets, exercise programmes and behavioural approaches have been started. Would only apply to children under 12 in exceptional circumstances

· Should do at least 60 minutes of moderate activity a day

Schools

· Should address provision of recreational spaces, catering and school travel plans to promote exercise and healthy eating. Staff should supervise and eat with younger children