BBC's Mark Macallum explains the tough new rules

The Royal College of Physicians has strengthened its rules on the use of anti-obesity medicines in a bid to have their use in treating the condition taken seriously.

Professor Peter Kopelman, chairman of the working party that produced the guidelines, said health authorities tended to view obesity as a self-inflicted problem and were reluctant to pay for its treatment.

Professor Kopelman on Radio 4's Today programme

Doctors who do not adhere to the guidelines face being reported to the General Medical Council for disciplinary hearings.

Under the guidance, anti-obesity drugs can only be prescribed after three other measures have failed - diet, exercise and changes in lifestyle patterns.

Treatment could be stopped

If all these measures fail, then prescriptions "may be justified in patients with a body mass index of 30 or greater", the clinical definition of obese.

The treatment should be stopped if the patient does not lose 5% of their weight within three months, the guidance says.

Patients who are simply overweight and want the pills to help them slim will be denied such treatment.

The guidance refers to use of the two anti-obesity products licensed for use in the UK, orlistat (known as Xenical) and phentermine (known as Ionamin or Duromine).

The college has produced more forceful guidelines

It also covers sibutramine, which is not yet licensed in the UK but could be soon.

Some health authorities have been accused of denying patients orlistat because of its cost. It has been estimated that treating most of Britain's 7.5 million clinically obese patients with the drug could cost the NHS £750m a year.

Professor Kopelman said: "We hope the recommendations in our report will give health authorities more confidence in using Xenical in the treatment of obesity.

"The current attitude is that obesity is a self inflicted condition and its management should be very much a patient's own responsibility.

"But obesity can be a serious medical condition at times associated with other important conditions such as diabetes and hypertension (high blood pressure).

"What health authorities need to appreciate is that a lot of their money is going into supporting those obese patients who run into trouble.

"We're not talking about people who want to lose a few pounds to fit into a bikini. There must be an acceptance in the country as a whole that we are really being threatened by obesity."

Improper use

As there is a danger that the drugs could produce adverse reactions, other doctors must keep their patients' GPs informed of any use of the drugs. Failure to do so would lead to disciplinary procedures, the guidance says.

Professor Kopelman said: "I don't think there's a concern about GPs, but private slimming clinics may be prescribing drugs inappropriately, and these practices should be exposed.

"It's a minority, but it's an important minority. If we're trying to change the culture regarding obesity this kind of thing doesn't help."

Dr Ian Banks is a GP in Northern Ireland who is taking part in the BBC's Fighting Fat, Fighting Fit campaign. He said there was a problem with patients seeking weight-lowering drugs from their GP as a "quick-fix" when they were concerned about their weight.

Taking the drugs inappropriately could lead to complications such as vitamin deficiency and "horrendous diarrhoea", he said.

"Worse, you're losing control over your own body because you're leaving it up to a drug instead of actually controlling something that should come much more naturally to a person unless you've got a medical reason for having to take it."

'Enjoy life'

He said being overweight was not something to get over-anxious about.

"Weight-lowering drugs should come way down the list for controlling your weight," he said.

"Only begin to think about weight-lowering drugs after you've talked to your GP. If you are not obese, you do not need them. You can still be fit and healthy and be slightly overweight.

"This is life - it is not a dress rehearsal, it's the real thing. Enjoy it."

Weight Watchers backed the guidelines.