The GLP-1 receptor agonists are the most effective weight loss agents ever brought to market, and their efficacy is entirely contingent on continued administration. Three randomized withdrawal studies across two molecules make this unambiguous: the STEP-1 extension found participants regained roughly two-thirds of their lost weight within a year of stopping, with blood pressure, lipids, glycaemia and inflammatory markers reverting alongside it. STEP-4 and SURMOUNT-4 showed the same pattern under cleaner designs, with the gap between continuing and stopping running to fifteen percentage points of body weight in under a year. The science of getting onto these drugs is mature. The science of getting off them is roughly a decade behind.

This episode explains why, and the answer is physiological rather than behavioral. Weight loss of any kind pr ...