Average weight change in the SURMOUNT-1 trial at weeks 4, 8, 12, 16, 20, 24 and beyond, next to the label's dose schedule. Trial averages, not a prediction.
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The average, week by week
These numbers come from SURMOUNT-1, the main weight trial of tirzepatide, the medicine in Zepbound. 2,539 adults without diabetes took it or a placebo for 72 weeks, with diet and activity counseling for everyone (SURMOUNT-1, NEJM, 2022).
SURMOUNT-1: average weight change by week (digitised)
Week
15 mg group's dose that week
5 mg group
10 mg group
15 mg group
Placebo
Week 4
2.5 mg
−3.3%
−3.3%
−3.2%
−1.1%
Week 8
5 mg
−6.0%
Not readable from the published figure
−5.9%
−1.8%
Week 12
7.5 mg
−7.9%
−8.9%
−8.4%
−2.1%
Week 16
10 mg
−9.2%
−11.1%
−10.6%
−2.4%
Week 20
12.5 mg
−10.5%
−12.8%
−12.6%
−2.6%
Week 24
15 mg
−11.6%
−14.2%
−14.6%
−2.9%
Week 36
15 mg
−13.7%
−17.3%
−18.2%
−3.3%
Week 48
15 mg
−15.0%
−19.1%
−20.2%
−3.2%
Week 60
15 mg
−16.0%
−20.6%
−21.6%
−3.4%
Week 72
15 mg
−16.1%
−20.9%
−22.0%
−3.3%
Read off Figure 3 of the Zepbound label (Zepbound label, FDA, 2026). Each dose's marker was read separately. At week 4 the three dose markers sit almost on top of each other. At week 8 the 10 mg marker is hidden behind the others, so that cell says it is not readable from the published figure. Week 72 values are the ones printed on the chart. In the trial, doses went up by 2.5 mg every 4 weeks until each group reached its dose, so the 5 mg group stayed on 5 mg from week 5 (SURMOUNT-1, NEJM, 2022). Averages in the trial, not a prediction. Your results will differ.
AVERAGE RESULTS IN THE TRIAL · DIGITISEDSURMOUNT-1: tirzepatide vs placebo, 72 weeks
Tirzepatide 5 mg
Tirzepatide 10 mg
Tirzepatide 15 mg
Placebo
Digitised from Figure 3 (SURMOUNT-1) of the Zepbound US label, one marker at a time. At week 4 the three dose markers sit almost on top of each other. At week 8 the 10 mg marker is hidden behind the others, so that point is left out. (Zepbound label, FDA, 2026). 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
Tirzepatide 5 mg
Tirzepatide 10 mg
Tirzepatide 15 mg
Placebo
4
−3.3%
−3.3%
−3.2%
−1.1%
8
−6.0%
Not readable from the published figure
−5.9%
−1.8%
12
−7.9%
−8.9%
−8.4%
−2.1%
16
−9.2%
−11.1%
−10.6%
−2.4%
20
−10.5%
−12.8%
−12.6%
−2.6%
24
−11.6%
−14.2%
−14.6%
−2.9%
36
−13.7%
−17.3%
−18.2%
−3.3%
48
−15.0%
−19.1%
−20.2%
−3.2%
60
−16.0%
−20.6%
−21.6%
−3.4%
72
−16.1%
−20.9%
−22.0%
−3.3%
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The dose alongside
For adults, the Zepbound label's schedule is 2.5 mg for 4 weeks, then 5 mg. After that, the dose can go up by 2.5 mg after at least 4 weeks on each dose, to a maximum of 15 mg. The label says 2.5 mg is not a maintenance dose (Zepbound label, FDA, 2026). The table's dose column is the fastest the label allows, which is also how the trial's 15 mg group stepped up (SURMOUNT-1, NEJM, 2022).
Plenty of people stay on a dose for longer, or stay on 5 mg or 10 mg. That is a decision for you and your prescriber. See the Zepbound guide for the full dose table.
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Weeks 1 to 12: side effects come first
In SURMOUNT-1, stomach side effects such as nausea and diarrhea were mostly mild to moderate and happened mainly while the dose was going up (SURMOUNT-1, NEJM, 2022).
Average weight loss in this stage was small and steady: about 3% at week 4, when the three dose markers sit almost on top of each other on the chart, and 8 to 9% at week 12, when they start to separate (Zepbound label, FDA, 2026).
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Weeks 16 to 72: the doses spread out, then slow
From week 16 the higher doses pull ahead. By week 72 the averages printed on the label's chart were −16.1% on 5 mg, −20.9% on 10 mg and −22.0% on 15 mg, against −3.3% on placebo (Zepbound label, FDA, 2026).
The paper's headline averages, which count people who stopped treatment differently, were −15.0%, −19.5% and −20.9% (SURMOUNT-1, NEJM, 2022). The paper says the 5 mg group had reached a plateau by week 72 and the higher doses were close to one (SURMOUNT-1, NEJM, 2022). More on plateaus.
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What the averages hide
An average sits in the middle of a wide spread. On 15 mg, 90.9% lost at least 5% of their weight, 56.7% lost at least 20% and 36.2% lost at least 25% (SURMOUNT-1, NEJM, 2022). Some people lost much less. If your results look very different, talk to your prescriber before changing anything.
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.
