There is no short cut to shedding flab and pills only work when combined with diet, exercise and changes in lifestyle. But ludicrous claims are made for commercial remedies which promise dangerous levels of weight loss, the experts say.
The first report to set out standards of good practice for the treatment of overweight and obese patients, published yesterday by the Royal College of Physicians, says anti-obesity drugs should only be prescribed to those medically defined as obese in whom other weight loss measures, such as diet and exercise, have failed.
No one should take the drugs for more than a year and they should be stopped early if the individual has failed to lose 10 per cent of his or her weight after three months.
Obese individuals are defined as those with a body mass index over 30. This is a measure of fatness obtained by dividing weight in kilograms by height in metres squared. The ideal BMI is 20 to 25 and above 25 is defined as overweight. A more direct measure of overweight is a waist measurement of 40 inches in men and 37 in women which is associated with increased medical problems.
The report was commissioned by the last government in response to concern that private slimming clinics were handing out pills without proper medical checks. Dr Peter Kopelman, chairman of the working party and an expert on obesity, said pills should never be used as the first line of attack. "The svelte ideal is not achievable with these drugs," he said.
"Slimming" pills was a misnomer because the only acceptable drugs in the treatment of obesity suppress appetite rather than make people thinner. Drugs which stimulate the burning of extra energy such as amphetamines and thyroid hormone should never be used because of their addictive properties, the report says.
Dr Kopelman said commercial weight loss preparations advertised in the media were not medicines and had not been scientifically evaluated. "We are concerned about these because the claims made for weight loss are totally unrealistic and if they were achieved they would be dangerous."
He said the use of drugs in very fat people was justified because obesity was a serious medical condition with an increased risk of joint disorders, heart disease and diabetes, but patients should be warned about side effects. Even a 10 per cent weight loss could significantly reduce these risks.
Although people tended to put weight back on after stopping the drugs, more research was needed into their long-term safety before they could be recommended for more than 12 months.
Professor David London, a member of the working party, said private slimming clinics had a duty to inform the patient's own GP when they were being treated. "People are embarrassed by obesity, they may go to a private clinic without telling their GP and end up getting a double dose of drugs which could be dangerous. It is very important that everyone involved in treatment should know about all the others."
A review of treatments for obesity published last month concluded that appetite suppressants can lead to large weight loss but the benefits tend to plateau after six months.
The report, published as an Effective Healthcare Bulletin, by the NHS Centre for Reviews and Dissemination, which is funded by the Department of Health, said fat people got little help from family doctors because they found obesity too frustrating a condition to treat. Getting rid of excess flab was a laborious task and the goal was so elusive that GPs tended to ignore the problem even though it was a major health issue.