Accepted answer
The data is unusually consistent: expect to regain roughly two thirds of what you lost within the first year off treatment, front-loaded, with cardiometabolic markers reverting on a similar timescale. Two randomised withdrawal designs and one off-treatment extension all converge on approximately the same fraction, which is a stronger result than any single trial.
The withdrawal and regain data
| Study | Design | Loss before withdrawal | Continued-treatment arm | Withdrawn arm | Fraction of loss regained |
|---|
| STEP 1 extension | Off-treatment observational follow-up, 52 weeks after a 68-week trial [1] | -17.3% at week 68 (semaglutide 2.4 mg) | Not applicable | -5.6% vs baseline at week 120 | about 11.7 percentage points regained, roughly two thirds |
| STEP 4 | Randomised withdrawal after a 20-week run-in [2] | -10.6% during run-in | A further -7.9% over 48 weeks | +6.9% over 48 weeks | about two thirds of run-in loss, in 48 weeks |
| SURMOUNT-4 | Randomised withdrawal after a 36-week open-label lead-in [3] | -20.9% during lead-in | A further -5.5% over 52 weeks (total -25.3%) | +14.0% over 52 weeks (total -9.9%) | about two thirds of lead-in loss, in 52 weeks |
| Liraglutide 3.0 mg withdrawal | Off-treatment follow-up after 56 weeks | Roughly -8% typical | Not applicable | Partial regain within the follow-up window | Substantial, similar direction, shorter observation |
Three independent designs, two different molecules, and the same fraction. That convergence is why the "two thirds in a year" figure is the one I would plan against.
Applied to your numbers
Starting weight: 108 kg
Current weight: 79 kg
Total lost: 29 kg (-26.9%)
Expected regain at the two-thirds figure:
29 x 0.67 = 19.4 kg
projected weight at 12 months off: 79 + 19.4 = 98.4 kg
Monthly rate if linear:
19.4 / 12 = 1.6 kg/month
Front-loaded, so realistically:
months 1-3: ~2.2 kg/month = 6.6 kg
months 4-8: ~1.6 kg/month = 8.0 kg
months 9-12: ~1.2 kg/month = 4.8 kg
------
19.4 kg
Note that a bigger loss means a bigger absolute regain but not a worse proportional outcome. You would still be roughly 10 kg below your starting weight at twelve months off treatment, which is not nothing and matters clinically.
Shape of the curve
Front-loaded. The regain rate is steepest in the first three to four months and decelerates thereafter, which mirrors the loss curve in reverse. The mechanism is straightforward: appetite suppression disappears over roughly four to five weeks as the drug clears, at which point you are eating against restored orexigenic drive while carrying the full counter-regulatory penalty of having lost weight. Early regain also includes several kilograms of fluid and glycogen as intake normalises, so the first month can look alarming and overstate the fat component.
Importantly, in the trial data the curves had not fully returned to baseline at one year and were still rising. Two-thirds at twelve months does not mean it stops at two thirds.
Cardiometabolic reversion
This is the part of the STEP 1 extension that gets least attention and matters most. Improvements in blood pressure, lipid profile, HbA1c and C-reactive protein all moved back toward baseline in parallel with the weight, with the exception of some residual benefit proportional to the residual weight loss. The practical reading: the metabolic benefit tracks the weight rather than persisting independently of it. If you had a 12 mmHg systolic improvement and you regain two thirds of the weight, plan on losing most of that improvement.
Which makes the residual matter. Every kilogram you do not regain carries proportional metabolic benefit with it, so partial success is genuinely valuable rather than a consolation prize.
What predicts a better-than-average outcome
The trials were not designed to answer this and the observational evidence is weak, so treat the following as reasoned rather than demonstrated. The factors most plausibly protective, in rough order:
- Retained lean mass and an established resistance-training habit. Higher fat-free mass means higher expenditure and a smaller energy gap to defend.
- A period of deliberate weight stability before stopping. Counter-regulatory signalling attenuates with time at a stable weight. Stopping at the bottom of an active decline is the worst moment to stop.
- Maintained daily activity, particularly step count. The strongest single behavioural correlate of maintained loss in the broader literature.
- A structured eating pattern that does not depend on absent appetite. If your intake control is entirely pharmacological, it disappears with the drug. If it is partly structural, it does not.
- Protein intake maintained through the transition. Satiety and lean-mass protection at the exact moment you need both.
Given your situation, the highest-value thing you can do is spend two to three months at a deliberate, stable maintenance weight before supply ends rather than continuing to lose right up to the last vial. That is the one variable fully in your control and it costs you nothing.
edited 16 Jan 2025 by pieter_maas — added the method parameters
3Three designs and two molecules converging on two thirds is about as good as evidence gets in this field. – Dr_Tomas_Kral 8 months ago 4The cardiometabolic reversion tracking the weight rather than persisting is the finding I wish were better known. – Dr_Ilse_Vandenberg 9 months ago Stabilising for a few months before the last vial rather than losing until supply runs out is advice I would give anyone in this position. – Dr_Idris_Coulibaly 34 days ago add a comment