But the procedure is not free of complications, with about half the patients in the study requiring follow-up surgery.

VicHealth warned that lap band surgery was not a panacea for Australia's obesity problem and called for a reduction in the marketing and and availability of junk food and sugary drinks.

Monash University Centre for Obesity Research and Education analysed the results of 3227 patients who had had gastric banding between 1994 and 2011, with the results of the study published in this month's edition of the medical journal Annals of Surgery.

The research showed that many patients kept the weight off. On average, the 714 patients who'd had the procedure more than a decade ago maintained a weight loss of 26 kilograms, or almost half their excess weight.

''For some people, losing 26 kilograms is extraordinary, for others it is a fairly modest effect, but that's the average. We have people who have lost well over 100 kilograms, we have others who have lost very few kilograms,'' said one of the study's authors, Professor Paul O'Brien.

Professor O'Brien, who was the lap-band surgeon for many of the patients, said the research showed lap-band surgery has a lasting impact on weight loss.

VicHealth nutrition manager and resident dietitian Julie Woods said while there was a place for lap-band surgery, more effort was needed to reduce the impact of junk food.

''If lap banding is all we did, the health system wouldn't cope. There is likely to be about 7 million obese Australians in the next 15 years,'' she said.

Lap-band surgery involves the placement of a gastric band at the top of the stomach that reduces hunger. After the surgery, patients are encouraged to eat small amounts, about 1200 calories a day, and exercise.

Professor O'Brien said while lap-band surgery had proved effective, it was not for everyone.

''You have to be obese, which is a BMI (body mass index calculated using height and weight) of greater than 30.''

The average age of patients in the study was 47; almost four out of five patients were women.

Lap-band surgery is commonly a day procedure and costs about $10,000 through the private health system, or it can be arranged through some public hospitals such as the Alfred.

The weight-loss method has become popular in recent years, with high-profile Australians including billionaire James Packer and media figure Harold Mitchell. Mr Mitchell is among the patients of Professor O'Brien.

An earlier version of this story stated that Mr Packer had been a patient of Professor O'Brien's. This is incorrect. The error was made in the editing process.