What the STEP 1 extension, STEP 4 and SURMOUNT-4 trials found when people stopped semaglutide or tirzepatide, and what to ask before you stop.
01
Semaglutide: the STEP 1 extension
In the STEP 1 extension, treatment and the lifestyle programme stopped at week 68 and 327 people were followed for another year. People on semaglutide had lost 17.3% by week 68. By week 120 they had regained 11.6 percentage points, about two-thirds of what they lost, leaving them 5.6% below where they started (STEP 1 extension, 2022).
AVERAGE RESULTS IN THE TRIAL · DIGITISEDSTEP 1 extension: a year after stopping semaglutide
Semaglutide, then stopped
Placebo, then stopped
Digitised from Figure 1A of the STEP 1 extension paper. Treatment, including the lifestyle programme, stopped at week 68. (STEP 1 extension, 2022). Points are read off the published chart, so they can be out by about a quarter of a percentage point. They are average results in the trial, not a prediction. Your results will differ.
Show the numbers
Week
Semaglutide, then stopped
Placebo, then stopped
4
−2.4%
−1.0%
8
−4.4%
−1.6%
12
−6.2%
−2.1%
16
−8.1%
−2.3%
20
−10.0%
−2.5%
28
−12.4%
−2.7%
36
−14.1%
−2.7%
44
−15.5%
−2.7%
52
−16.6%
−2.7%
60
−17.0%
−2.3%
68
−17.3%
−2.0%
75
−13.9%
−1.7%
80
−11.3%
−1.0%
104
−6.7%
−0.4%
120
−5.6%
−0.1%
Improvements in blood pressure, blood fats and blood sugar also moved back towards where they started for most measures (STEP 1 extension, 2022). These results were exploratory (STEP 1 extension, 2022).
02
Semaglutide: STEP 4
In STEP 4, everyone took semaglutide for 20 weeks and lost 10.6% on average. Then some switched to placebo. From week 20 to week 68, those who stayed on semaglutide lost another 7.9%, while those on placebo gained 6.9% (STEP 4, JAMA, 2021).
03
Tirzepatide: SURMOUNT-4
In SURMOUNT-4, everyone took tirzepatide for 36 weeks and lost 20.9% on average. Then half switched to placebo. Over the next 52 weeks, those who stayed on tirzepatide lost a further 5.5%, while those on placebo saw their weight rise by 14.0% (SURMOUNT-4, JAMA, 2024).
AVERAGE RESULTS IN THE TRIAL · DIGITISEDSURMOUNT-4: staying on tirzepatide vs switching to placebo
Stayed on tirzepatide
Switched to placebo
Digitised from Figure 2A of the SURMOUNT-4 paper. Everyone took tirzepatide for 36 weeks, then half switched to placebo. (SURMOUNT-4, JAMA, 2024). Points are read off the published chart, so they can be out by about a quarter of a percentage point. They are average results in the trial, not a prediction. Your results will differ.
Show the numbers
Week
Stayed on tirzepatide
Switched to placebo
4
−3.5%
–
8
−6.3%
–
12
−9.0%
–
16
−11.6%
–
20
−14.0%
–
24
−16.4%
–
28
−18.2%
–
32
−19.7%
–
36
−21.0%
−21.0%
40
−22.3%
−18.7%
52
−24.4%
−15.3%
64
−25.7%
−13.2%
76
−26.1%
−11.2%
88
−25.8%
−9.5%
By week 88, 89.5% of those who stayed on tirzepatide had kept at least 80% of the weight they lost, against 16.6% of those switched to placebo (SURMOUNT-4, JAMA, 2024).
04
Before you stop
The NHS says to talk to your doctor if you want to stop, and not to stop suddenly (NHS, 2026) (NHS, 2026).
In England, NHS semaglutide for weight is limited to 2 years in specialist services (NICE TA875, 2023). NHS England says tirzepatide has no set stopping rule or maximum treatment period (NHS England, 2026).
If you do stop, keep weighing in and measuring your waist on the same schedule. A record makes it easier to spot change early and talk it through.
Checked 25 Oct 2026. Trial figures are average results in the trial, not predictions. Labels change; your prescriber and the leaflet in your pack have the current version.
Pip Body Scan is a personal progress record. It is not a medical device and does not give medical advice, diagnose conditions or recommend doses. Speak to your prescriber or another qualified healthcare professional about symptoms, side effects or changes to your treatment.
