Doubts over anti-obesity drugs

Anti-obesity drugs are unlikely to permanently reduce patients' weight, Canadian research findings suggest.

A meta-analysis showed little evidence that orlistat, sibutramine or rimonabant reduced patients' weight by 5 per cent as required by NICE. Such 'modest' weight loss could mean many patients will remain significantly overweight or obese despite drug treatment, say the researchers.

The study focused on 30 randomised placebo-controlled studies into anti-obesity drugs, involving almost 20,000 patients treated for at least one year.

Analysis showed that compared with placebo, orlistat reduced weight by an average of 2.9kg, sibutramine by 4.2kg and rimonabant by 4.7kg. Because the average starting weight of participants was 100kg, the drugs often failed to reduce significant body weight.

Between 30 and 40 per cent of participants dropped out of the trials, potentially affecting perceived effectiveness of the drug.

In 2006 NICE published public guidance on obesity. Use of orlistat and sibutramine was recommended in patients with a BMI of 30 or more who fail to respond to lifestyle interventions.

According to NICE, treatment should only be continued beyond six months if the patient manages to lose 5 per cent of their body weight in that time.

Dr David Haslam, clinical director of the National Obesity Forum and Hertfordshire GP, said that average weight loss was not a useful measure. This is because patients are responders or non-responders.

'Responders will lose a lot more,' said Dr Haslam, adding that this could be as much as 10-15 per cent in some patients.

If no response is seen at six months, GPs should 'try a different medication or reinforce lifestyle modifications', he said.

The research also found that the effect of weight loss drugs on comorbidities differed.

All three lowered cholesterol and orlistat was seen to reduce incidence of obesity. Sibutramine raised BP and pulse rate.

Anti-obesity drugs

  • Average weight loss less than 5 per cent body weight.
  • All three reduced cholesterol.
  • Orlistat reduced diabetes.
  • Sibutramine raised BP.
  • Rimonabant improved glycaemic control.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins


Already registered?

Sign in

Just published

Kamila Hawthorne

GP crisis could force one in four practices to close, says RCGP

Unmanageable pressure could force more than a quarter of GP practices to close, polling...

COVID-19 vaccine in pregnancy

Vaccination in pregnancy cuts COVID-19 risk for mother and baby

Vaccination against COVID-19 during pregnancy reduces the risk of infection and hospitalisation...

Child using smartphone

NICE backs digital CBT games for children with anxiety or low mood

GPs could prescribe CBT-based digital games, videos and quizzes for children and...

GP surgery sign

GP pressure to continue as experts warn NHS backlog will remain through 2023

General practice faces continuing heavy pressure after experts warned that the record...

Close-up of a man loading a shotgun

BMA updates GP firearms guidance as digital marker goes live on EMIS

The BMA has updated its guidance for GPs on firearms licensing following the release...

Map pins

Severely underdoctored areas spread across nearly every NHS region

Severely underdoctored areas exist in nearly every NHS region across England, figures...