What does the withdrawal-extension data say about regain trajectory?

Scale weight, waist circumference and a repetition maximum, all logged weekly.

I would like help reading this properly rather than being told what conclusion to reach.

I have the full report including the method section, so I can quote specifics if that helps.

What would I need in addition before this supported a decision?

Worth being precise here: this is the question that reframes the whole class from a course of treatment to an ongoing one.

The counter-regulatory response — raised ghrelin, reduced leptin, reduced peptide YY, plus adaptive thermogenesis — is measurable a year or more after weight loss and is the physiological explanation.

In practice, published follow-up after semaglutide withdrawal found roughly two thirds of lost weight regained within a year, with blood pressure, lipids and glycaemia reverting towards baseline in parallel.

Observational maintenance cohorts consistently identify high physical activity and continued self-monitoring among sustained maintainers.

The caveat is that stopping and starting decisions are clinical and depend on why treatment was started in the first place.

The counter-regulatory response is physiology, not weakness.

edited 3 Mar 2026 by m_haraldsen — clarified the distinction between purity and content

Answering this needs to separate stopping abruptly from tapering, although the evidence on tapering is thin.

A maintained loss of five to ten per cent retains a meaningful fraction of the cardiometabolic benefit, which means partial regain is not the same as total failure.

STEP-4 withdrew semaglutide after a run-in and reported that participants switched to placebo regained weight steadily while those continuing lost further, which is about as clean a demonstration of the mechanism as trial design allows.

The persistence of counter-regulatory hormonal changes after weight loss is documented for at least a year in controlled follow-up studies.

Tapering is plausible and unevidenced. Say both halves.

Answer first: regain after withdrawal is the expected result in every trial that has measured it, because the intervention treats a condition rather than curing it.

Planning for maintenance before reaching the target changes the outcome more than any decision made afterwards.

STEP-4 and SURMOUNT-4 are the withdrawal trials for semaglutide and tirzepatide respectively and are the appropriate citations for this question.

Regain is the default. Plan for maintenance before you need it.

On the detail: the counter-regulatory response is why maintenance is harder than loss and why it needs its own plan.

Tapering rather than stopping abruptly is widely discussed and has essentially no controlled evidence behind it, which should be said plainly rather than dressed up.

The body-composition substudies in the major programmes consistently report that the proportion of weight lost as fat mass is approximately three quarters or better, with the lean-mass fraction falling within the range seen in dietary weight loss of comparable magnitude[1].

Partial maintenance retains real benefit. It is not all or nothing.

edited 3 Mar 2026 by RP_C18 — added the citation requested in comments