More than one-third (35 per cent) of people who took a new drug for treating the condition lost more than one-fifth of their total body weight, according to a global study involving researchers at University College London (UCL).

The findings are being hailed for their potential to improve the health of people with obesity.

Researchers say that for the first time it is possible to achieve through drugs what was previously only possible through weight-loss surgery.

The drug, semaglutide, works by hijacking the body's own appetite regulating system in the brain, leading to reduced hunger and kilojoule intake.

Rachel Batterham, professor of obesity, diabetes and endocrinology who leads the Centre for Obesity Research at UCL and the UCL Hospital Centre for Weight Management, is one of the principal authors on the paper, which involved almost 2000 people in 16 countries.

"The findings of this study represent a major breakthrough for improving the health of people with obesity," she said.

"Three-quarters of people who received semaglutide 2.4mg lost more than 10 per cent of their body weight and more than one-third lost more than 20 per cent.

"No other drug has come close to producing this level of weight loss - this really is a game changer."

The average participant in the trial lost 15.3kg, according to the study published in the New England Journal for Medicine.

This was accompanied by reductions in risk factors for heart disease and diabetes, such as waist circumference, blood fats, blood sugar and blood pressure, and reported improvements in their overall quality of life.

With evidence from this trial, semaglutide has been submitted for regulatory approval as a treatment for obesity to the UK's National Institute of Clinical Excellence, the European Medicines Agency and the US Food and Drug Administration.

Australian Associated Press