Coming off: what the pharmacology permits

That does not settle the question, because the best argument for a gradual reduction is not pharmacological. It is that the return of appetite is the thing being managed, that it returns over weeks rather than instantly, and that a person given a month of partial appetite suppression in which to establish different eating patterns may be better placed than a person whose appetite returns fully while they are still eating as though it had not. That is a plausible behavioural hypothesis. It has not been tested in a randomised trial and the Journal is not aware of one being planned.

What the three designs agree on

The parent programmes establish the losses from which the withdrawal arms fall: approximately 14.9 per cent at sixty-eight weeks for semaglutide 2.4 mg in adults without diabetes, approximately 20.9 per cent at seventy-two weeks for tirzepatide 15 mg, and — the only continuous two-year comparator anybody has — approximately 15.2 per cent sustained at week 104 with treatment maintained throughout.¹²

Read together, the withdrawal evidence supports four statements and does not support a fifth. Regain begins promptly after cessation, within weeks rather than months. It proceeds at a decelerating rate, with the steepest portion in the first three to six months. It does not, within twelve months of follow-up, return participants fully to their original baseline; residual reductions of roughly five to ten per cent persist at one year in all three datasets. And continued treatment maintains and usually extends the loss, with the extension diminishing as the plateau is approached.

The statement not supported is that the drugs cause weight regain, or that stopping leaves a person worse off than never having started. Nothing in these datasets shows overshoot above the original baseline at a group level. Every arm that stopped remained below where it began at the end of follow-up.

The Journal makes this point repeatedly because the contrary claim circulates widely and is often accompanied by a mechanistic story about metabolic damage. The withdrawal trials are the direct test of that claim and they do not support it. What they do support is the unremarkable proposition that a treatment for a chronic condition works while it is being taken.

The variance in regain, which is as large as the variance in loss

Mean regain trajectories conceal a distribution as wide as the one that characterises the initial response. In the reported withdrawal arms, some participants returned to within a percentage point of their original baseline within a year while others retained most of their loss with no pharmacological support whatever. The interquartile ranges in the published figures are broad, and the trials were not designed to explain them.

Nothing measured at randomisation predicts an individual regain trajectory usefully. Baseline body mass index, the magnitude of the initial loss, age, sex and diabetes status all shift the mean modestly and leave the spread largely intact. The behavioural variables that plausibly matter — what a person was eating and doing during the loss, and whether any of it persisted — were not measured with the granularity required to test them.

This is the same structural gap that runs through the whole field: the mean effects are well characterised and the variance is not. It has a specific practical consequence here. A person deciding whether to stop cannot be given a personal probability of holding their weight, because no such probability has been established, and any source offering one is offering a group mean dressed as a prediction.

Resuming after an interruption is a fresh escalation

This is the most practically consequential item in the whole subject and the one least often stated in advance. Gastrointestinal tolerability to these agents develops over weeks of continued exposure and decays when exposure is removed. After four weeks without the drug, plasma concentrations are a small fraction of steady state and the tolerability accommodation has substantially reset. Resuming at the previous maintenance dose therefore presents the system with an exposure step it has not experienced for a month.

The clinical convention — resume at a lower dose and re-escalate — follows from the pharmacokinetics rather than from caution.³ Product labelling for several agents in the class advises consideration of re-initiation at a lower dose after an extended interruption, and the threshold at which this applies differs between products, which is a detail worth checking against the specific label rather than a general rule.

The shortage period demonstrated the consequence of ignoring this at scale. Large numbers of people lost access for six to ten weeks, resumed where they had left off, and experienced nausea and vomiting considerably worse than during their original escalation. It was predictable, it was predicted by anybody who had read the label carefully, and it was almost never communicated.

The case for tapering, stated as fairly as we can

There is no withdrawal syndrome from these agents, no dependence, and no pharmacological reason to reduce gradually rather than to stop. A seven-day half-life produces its own taper: concentrations halve within a week and fall to a few per cent within a month regardless of intent. On the pharmacology alone, a planned taper accomplishes nothing that stopping does not.

The behavioural argument is different and better. Appetite returns over weeks. A person whose dose is reduced in steps experiences that return in stages, while continuing to have some pharmacological support, and has a window in which to establish eating patterns that will have to hold without the drug. A person who stops outright experiences the same return without that window. Whether the window produces better outcomes is an empirical question that has not been asked in a trial.

The Journal’s position is that the behavioural argument is worth making on its own terms and worth not dressing in pharmacological clothing. What a taper cannot do is prevent regain, since the withdrawal trials establish that ongoing exposure is what holds the weight. Presenting a taper as a way of stopping without regaining is a claim the evidence does not support in any form.

The first six weeks after the last injection

Exposure falls on a predictable schedule. A week after a final weekly injection roughly half the steady-state concentration remains; at two weeks a quarter; at four weeks a few per cent. Appetite returns along a curve that lags the concentration curve somewhat, and delayed gastric emptying resolves over a similar interval, so the sensation of early fullness that has been governing meal size for months disappears over about a month.

What people report, and the Journal reports it as report rather than as measurement, is that the appetite return is experienced as abrupt rather than gradual — as a threshold being crossed somewhere in the third or fourth week rather than as a smooth ramp. That is consistent with a non-linear relationship between receptor occupancy and the perceived effect, which is what the dose-response data would predict, and it is not consistent with the exposure curve alone.

Glycaemic parameters follow their own timescale. Fasting glucose responds within days to weeks; HbA1c, which reflects the preceding three months with the recent weeks weighted most heavily, will not show the full consequence of stopping for a full quarter. A panel drawn four weeks after cessation will understate the change, and this is a specific and common misreading. In the trial population with type 2 diabetes, where glycaemic control was a co-primary concern, the treatment effect on HbA1c was of the order of one and a half percentage points, which is the scale of what a cessation eventually undoes.⁴

How the Journal reports a regain figure

Four things accompany every regain number in these pages. Which withdrawal design it comes from, because an off-treatment extension and a randomised placebo switch are different experiments. Whether the lifestyle intervention continued in the arm being described. What the denominator is — regain as a percentage of body weight, as a percentage of the weight lost, or as a final position relative to original baseline, three quantities that are routinely quoted interchangeably. And the follow-up duration, because the regain curve decelerates and a figure at six months is not a figure at a year.

The third of those is where most of the misreporting happens. A statement that participants regained two-thirds is a proportion of loss; a statement that they regained eleven per cent is a proportion of body weight; a statement that they finished 5.6 per cent below baseline is a final position. All three can describe the same arm and they are not interchangeable.

Where a source we are quoting has not stated its denominator, we say that rather than inferring it. Readers who find a regain figure in these pages without its design and its denominator have found an error, and the standards desk would like to hear about it at standards@compoundjournal.com.

What this piece is not

This is reporting on a body of trial evidence and it is not advice about whether or how to stop taking a medicine. The decision to discontinue an agent prescribed for glycaemic control, cardiovascular risk or kidney disease is materially different from the decision to discontinue one prescribed for weight, and in every case it belongs with a clinician who has seen the person and knows why the drug was started.

Two further notes. Compounds sold for research use only are not approved for human use in any jurisdiction, and nothing here should be read as guidance about using them or about stopping their use. And where this piece describes what clinicians report doing about maintenance dosing, that is description of practice and not a schedule anybody should adopt from a magazine.

The Journal takes correspondence on this subject at letters@compoundjournal.com and factual challenges at standards@compoundjournal.com. Letters describing a personal experience of stopping are read with attention and are published, where they are published, as accounts rather than as evidence — a distinction this department tries hard to preserve in both directions.

What the shortage years demonstrated, at a scale no trial will ever match, is that this class is now being stopped and restarted routinely by circumstance rather than by decision. That is the discontinuation that actually happens, and there is no literature on it at all. The Journal regards documenting it as reporting rather than research, and will keep doing so.