The Day the Balloon Comes Out

An intragastric balloon is placed in the stomach and removed six months later. Everyone knows the date in advance, which makes it an unusually clean experiment in what happens when a weight intervention ends. In this trial, the group whose treatment stopped began regaining. The group whose semaglutide continued kept losing.^[1]

What happened at the removal date

Forty adults with a BMI of at least 27 received a balloon, half of them also starting semaglutide in the second month and continuing it after the balloon came out. Both groups were measured at three, six and twelve months.

The curves separate on a date that was in the calendar from the beginning.

By twelve months the two groups differed by more than double, and the reason is entirely visible in the middle row. One intervention ended on schedule and its effect began reversing; the other continued and its effect continued.

Why this shows the theme so clearly

Every withdrawal trial covered on this register shows the same thing — weight returns when treatment stops. What makes them harder to read is that people stop drugs for messy reasons at messy times: side effects, cost, supply, a lost prescription, a change of insurance. Discontinuation is entangled with everything that caused it.

That is a cleaner demonstration than the drug-withdrawal literature can usually manage, and it points the same way: these interventions work while they are happening. The trial evidence on stopping a GLP-1 is in what happens when you stop, and what people actually did afterward in ordinary care is in what people actually do after stopping.

It also sits alongside the surgical version of the same question. Bariatric surgery does not come out on a date, and weight still returns for many people — weight regain after bariatric surgery, where a randomized trial now shows what adding semaglutide does for those it failed.

Forty people

• The paper describes itself as a “prospective, randomized cohort”, which names two different designs in one phrase. We report it as written and cannot tell you which it was.
• Baseline weights are not given in the abstract, so 33 kg cannot be converted into a percentage — and percentages are what every other trial reports.
• Twelve months, with no follow-up after the semaglutide would eventually stop too.
• Intragastric balloons are a niche intervention, and this says nothing about how the combination would behave outside that setting.

The finding worth keeping is not the size of the numbers. It is their shape: two curves that ran together while both treatments were active and separated the moment one of them ended.