For people who are considered overweight or obese, with a body mass index (BMI) of 27 or above, and who wish to lose their weight, a new type of treatment is being offered in the UK. It’s called the Obalon balloon, and it’s essentially a balloon that sits in the stomach with the purpose of reducing appetite by taking up space. Although, trials in the UK showed some success, it might be a long time before the U.S. sees this type of treatment, even as the gastric balloons also gain popularity in other parts of the world.

The Obalon balloon is designed differently from other gastric balloons. Rather than passing an actual balloon through a patient’s mouth or operating through their abdomen, a patient only needs to ingest a capsule. The capsule contains the balloon and is attached to a super-small catheter, which is used to inflate it once it enters the stomach. Patients who opt for the procedure can ingest another balloon 30 days later, and then another one 60 days after the first — at a cost starting at £1,995 and rising another £1,000 for each balloon after that — for a total duration of 90 days, according to the UK’s National Health Service (NHS).

During the 12-week period, “the balloon(s) will act to educate them (the patients) about portion size and retrain their brain and their mindset a little,” Dr. Sally Norton, a bariatric surgeon at Spire Hospital, in Bristol, England, where the procedure is offered, told CBS News. The balloon helps people get full faster, and therefore, eat less. Patients who tested the balloon lost an average of 17 lbs., which the NHS says is similar in effectiveness to other forms of gastric banding and gastric bypass. The trial involved 119 obese patients, of whom half received one balloon, 52 received two, and six received three.

The problem, however, is that the procedure doesn’t seem to be long-lasting. “When they take the balloons out, what happens is the stomach hasn’t shrunk,” Tim Bean, a UK-based fitness expert, told CBS. “So you’re left with the same size stomach, or possibly [one that is] even bigger than there was beforehand.”

Just like many gastric balloons before it, the Obalon considered an investigational device by the Food and Drug Administration (FDA), with the chances of its approval unclear. Gastric balloons have long been controversial in the U.S., where bariatric surgeons believe it’s ineffective. One reason they’re hesitant to look into approval is because they don’t believe the procedure reduces enough ghrelin, the hormone responsible for hunger, in the patient, according to ABC News. Indeed, if the procedure is to work, the patient must stick to a diet even after the balloons are replaced, and that can be hard if the body hasn’t really adjusted. Other complications can also be dangerous, including a deflated balloon that can clog up the intestinal tract.

Still, the balloons have gained in popularity elsewhere, as shown by their use in the UK. For people who don’t want to pay for the balloons, the NHS also offers their own version. In 2010, a report from Brazil also showed positive results, according to MedPage Today. Patients with an average weight of 220 lbs. went down to an average of 199 lbs. after five to seven months.

The researchers of that study, and the manufacturers of Obalon say that the balloons are good for people who have failed to diet, or who can’t tolerate or refuse to get gastric bypass or gastric banding. Consistent with the rise in obesity rates, the number of patients who underwent bariatric surgery rose from about 16,000 in the early 1990s to more than 103,000 in 2003, according to the National Institutes of Health. In 2008, rates rose to almost 125,000 — and were expected to keep on rising.