A swallowable balloon which makes people feel full can lead to dramatic weight loss in just four months, research suggests.
Obese people lost an average of 2st 6lb over 16 weeks, a study found, with experts suggesting the technique could be used as an alternative to drastic weight-loss surgery.
The Elipse Balloon is contained inside a capsule which is swallowed with a drink of water. The capsule is attached to a hollow plastic tube.
A doctor uses imaging to check the balloon is correctly in place before filling it up, via the tube, with almost a pint of water. The tube is then detached and removed.
After 16 weeks, a valve disintegrates and the device is excreted safely by the body.
In the new study presented at the European Congress on Obesity in Porto, Portugal, the balloon was given to 42 obese people (29 men and 13 women).
They were typically aged 46, had a body mass index (BMI) of 39 and weighed just over 17st on average.
After 16 weeks, typical weight loss per person was 2st 6lb and people lost more than 14% of their total body weight (around a third of their excess weight).
The balloon, which costs around £3,400, is available in several countries around the world and privately in the UK. The NHS is investigating similar methods.
Dr Roberta Ienca, from the University of Rome, who led the study, said: "The reaction of patients is incredible. They are very happy about the results they were able to achieve.
"During my daily phone contacts with my patients, they shared with me their pictures and the amount of weight they lost."
She said people were "very satisfied" with the results. Work was also carried out with patients on changing their eating habits long-term, she said.
Professor Jason Halford, treasurer of the European Association for the Study of Obesity, from the University of Liverpool, said the device helped people manage their appetite and modify their food intake.
"In that context, it could be a solution for people who don't want to go for full bariatric (weight-loss) surgery," he said.
"With bariatric surgery, there are potential complications, it's a very permanent change in your life and it's not easily reversible.
"People are looking for alternatives."
He said the balloon could also provide an alternative to anti-obesity drugs and may be useful for people who have found that drugs do not work.
He said "potentially millions could benefit" on the NHS, though clinical commissioning groups (CCGs), which control large chunks of NHS funds, would need to be willing to pay for them.
"I think if studies are there and it's cost-effective ... I think it should be considered (on the NHS)," he said.
Dr Simon Cork, from Imperial College London, warned that patients were likely to regain weight once the balloon was removed.
"Nevertheless, gastric balloons are still useful for some patients, and the introduction of a device which doesn't require surgery to implant is a positive step forward," he said.