Tirzepatide and the Weight-Regain Question: What Happens When Treatment Stops

The question of what happens when an incretin-based weight treatment is stopped has been answered directly by a randomisedwithdrawal trial. After 36 weeks of open-label tirzepatide, during which mean weight fell by 20.9 per cent, 670 participants wererandomised either to continue or to switch to placebo for a further 52 weeks. Those who continued lost a further 5.5 per cent;those switched to placebo gained 14.0 per cent, a difference of 19.4 percentage points. At week 88, 89.5 per cent of the continuinggroup had maintained at least 80 per cent of their lead-in weight loss against 16.6 per cent of those withdrawn. Two qualificationsbelong with those figures. The placebo group was still 9.9 per cent below its starting weight at the end, so withdrawal did notsimply undo the treatment; and regain was highly variable, with 54 of 308 withdrawn participants regaining less than a quarter ofwhat they had lost while 74 regained three quarters or more. This review sets out what the trial establishes and what it leavesopen.