Image copyright Getty Images Image caption The weight-loss drug lorcaserin has shown promising results

A major study has found promising results for the safety of a weight-loss drug available in the US.

The study, published in the New England Journal of Medicine, says adults using the drug lorcaserin lost an average of 4kg (8.8lb) over 40 months.

It says the drug, which works by suppressing appetite, does not put people at greater risk of heart issues.

But experts emphasise the importance of long-term lifestyle changes in achieving effective weight loss.

Lorcaserin has been available in the US for several years under the name Belviq, but it has yet to be approved for use in Europe.

The study followed 12,000 overweight or obese adults in the US over three-and-a-half years.

After 40 months, people prescribed lorcaserin were three times more likely to have lost 5-10% of their body weight than those using a placebo, according to Dr Erin Bohula, one of the study's lead authors.

Tests for heart valve damage showed no significant differences compared to those taking the placebo. This has been a key concern over the safety of other slimming pills.

Patients using the drug were also at a slightly lower risk of type 2 diabetes. It is not yet known if lorcaserin has any other side effects.

The pill is taken twice a day and costs about $220-290 (£155-225) per month in the US.

The drug does not have a European licence. In England, it would have to be approved by the National Institute for Health and Care Excellence (Nice) and in Scotland by the Scottish Medicines Consortium before it could be prescribed.

However, it could offer an alternative to invasive weight-loss procedures such as gastric band surgery.

Over half of UK adults are thought to be overweight or obese. Both conditions carry an increased risk of type 2 diabetes, cancer and heart disease.