How Much Weight Do People Lose on Zepbound? The Numbers From Every Trial
Every published tirzepatide weight-loss figure in one place — by dose, by population, by trial, and by how it was measured — plus what the same drug does outside of a clinical trial.
Semaglutides.org is for information only and is not medical advice. Always talk to a licensed healthcare provider about your own care. Some links to telehealth services are affiliate links, labeled where they appear.
Zepbound is the US brand name for tirzepatide when it is prescribed for weight management. Mounjaro is the same drug prescribed for type 2 diabetes. Weight-loss figures come from both programs, and they are not interchangeable, because the populations are different.
Below is every published average, sorted by which question it answers. None of this is a prediction for any individual, and none of it is a recommendation about dose. Trials report group averages, and individual results in those same trials varied enormously.
What did the main Zepbound trial find?
SURMOUNT-1 is the trial that got Zepbound approved. It enrolled 2,539 adults with a BMI of 30 or higher, or 27 or higher with a weight-related condition, and excluded anyone with type 2 diabetes. Average starting weight was about 105 kg (231 pounds) and average BMI was about 38. Everyone, including the placebo group, got lifestyle counseling aimed at a 500-calorie daily deficit and at least 150 minutes of activity a week.
At 72 weeks [1]:
| Dose | Mean weight change | Lost 5% or more | Lost 20% or more |
|---|---|---|---|
| Tirzepatide 5 mg | -15.0% | 85% | not reported separately |
| Tirzepatide 10 mg | -19.5% | 89% | 50% |
| Tirzepatide 15 mg | -20.9% | 91% | 57% |
| Placebo | -3.1% | 35% | 3% |
In pounds, for the average participant, the 15 mg figure works out to roughly 48 pounds.
The FDA’s own statistical review of the application put the 10 mg and 15 mg differences from placebo at -16.4 percentage points (95% CI -17.9 to -14.8) and -17.8 points (95% CI -19.3 to -16.3) [2].
How much do people with type 2 diabetes lose?
Less. Reliably less, and the same is true of every drug in this class.
SURMOUNT-2 (n=938) ran the same 72-week design in adults with a BMI of 27 or higher who also had type 2 diabetes with an HbA1c between 7% and 10%. Weight change was -12.8% on 10 mg and -14.7% on 15 mg, versus -3.2% on placebo — treatment differences of -9.6 and -11.6 percentage points [3].
So the same dose that averaged about 21% in people without diabetes averaged about 15% in people with it. Researchers generally attribute this to differences in baseline metabolic state and to other glucose-lowering drugs taken alongside, but it is not fully explained.
If you see a single headline percentage for tirzepatide with no population attached, it is probably the SURMOUNT-1 number, and it does not apply to everyone.
What happens if you are already losing weight through diet and exercise?
SURMOUNT-3 answered this directly. It put 579 adults through a 12-week intensive lifestyle program first, and only randomized the people who had already lost at least 5% of their body weight.
From that new, lower starting point, the tirzepatide group lost a further 18.4% over 72 weeks while the placebo group gained 2.5% — a difference of -20.8 percentage points (95% CI -23.2 to -18.5). Adding in the lead-in, total weight loss in the tirzepatide arm exceeded 26% [4].
Two things stand out. The drug added to lifestyle change rather than substituting for it. And the placebo group’s slow regain, despite being people who had just succeeded at a structured program, is a useful reality check about how hard maintenance is without ongoing treatment.
How does Zepbound compare with Wegovy head-to-head?
SURMOUNT-5 is the only randomized trial that put the two leading obesity drugs against each other. It enrolled 751 adults with obesity and no diabetes, average starting weight about 113 kg, average BMI 39.4, and ran 72 weeks [5].
| Measure | Tirzepatide (max tolerated) | Semaglutide 2.4 mg |
|---|---|---|
| Mean weight change | -20.2% (95% CI -21.4 to -19.1) | -13.7% (95% CI -14.9 to -12.6) |
| Absolute weight loss | about 22.8 kg | about 15.0 kg |
| Waist circumference | -18.4 cm | -13.0 cm |
| Lost 25% or more | 31.6% | 16.1% |
All comparisons favored tirzepatide at p<0.001. Side effects in both arms were mostly gastrointestinal and concentrated during dose escalation.
The key limitation: it was open-label. Participants and investigators knew which drug was which, which can influence reported symptoms and behavior. It also tested semaglutide 2.4 mg, not the higher 7.2 mg dose (Wegovy HD) that the FDA approved on March 19, 2026. No trial has compared tirzepatide with that dose.
What does the newest competitor trial show?
In February 2026, Novo Nordisk announced REDEFINE 4 — a trial the company ran itself, comparing its experimental combination CagriSema against tirzepatide 15 mg in 809 adults with obesity over 84 weeks.
Tirzepatide won. Under the efficacy estimand, weight loss was 25.5% for tirzepatide versus 23.0% for CagriSema. Under the treatment-regimen estimand, 23.6% versus 20.2%. CagriSema failed to prove non-inferiority [6].
That trial is also a useful illustration of the estimand problem. The same tirzepatide arm is reported as both 25.5% and 23.6%. Neither is wrong. The first estimates what would have happened if everyone had stayed on treatment. The second counts everyone regardless of whether they stopped. Whenever two sources quote different numbers for the same trial, this is usually why.
What are the numbers outside the United States?
Regional trials tested the same doses in different populations, and the figures shift:
- SURMOUNT-J (Japan, n=225 in the analysis set): placebo-adjusted weight change of -16.1% at 10 mg and -21.1% at 15 mg at 72 weeks. Japan uses a lower BMI threshold to define obesity [7].
- SURMOUNT-CN (China, n=210): -13.6% at 10 mg and -17.5% at 15 mg at 52 weeks, versus -2.3% on placebo. Participants were younger (average 36) and lighter (average 92 kg) than in SURMOUNT-1 [8].
Shorter trial, different population, different number. That is normal and not a contradiction.
How much do people actually lose outside of a trial?
This is where the gap opens up.
A study using Truveta de-identified US electronic health records followed 2,396 adults with obesity and no diabetes who started tirzepatide or semaglutide between December 2023 and June 2024 and stayed on treatment. At six months, average weight change was -11.15% on tirzepatide and -8.83% on semaglutide, an adjusted difference of -2.32 percentage points (95% CI -3.17 to -1.48) [9].
The direction matches SURMOUNT-5. The magnitude does not match SURMOUNT-1. Three reasons:
- Six months is not 72 weeks. Trial participants were still losing at month six.
- Dose. Only 42.4% of tirzepatide patients had reached 10 mg or higher, against a trial design that pushed everyone toward their maximum tolerated dose.
- Support. Trial participants got structured dietitian counseling, free medication and visits every few weeks.
There is a fourth factor that does not show up in this particular study because it only included people who stayed on treatment: a lot of people do not. In US commercial claims data covering 33,607 people without diabetes, one-year persistence on tirzepatide was 64.0% in 2023 and 64.8% in the first half of 2024 — better than semaglutide’s 39.8% and 58.6% in the same years, and much better than the 33.2% overall figure from 2021, but still well below trial completion rates [10].
Does weight loss keep going after 72 weeks?
Mostly it holds rather than continues.
The SURMOUNT-1 prediabetes extension treated 1,032 participants for 176 weeks — nearly three and a half years including follow-up. Mean weight change at week 176 was -12.3% on 5 mg, -18.7% on 10 mg and -19.7% on 15 mg, versus -1.3% on placebo [11]. Compare that with the 72-week figures of -15.0%, -19.5% and -20.9%. The group average drifted very slightly upward but stayed close to the peak.
SURMOUNT-MAINTAIN looked at this differently, over 112 weeks. People who spent 60 weeks reaching an average body weight of about 89 kg and then stayed on their maximum tolerated dose were at 88.7 kg a year later — essentially unchanged. Those who dropped to 5 mg were at 94.6 kg, an average regain of about 5.6 kg [12].
What do pooled analyses say?
A network meta-analysis combining eight randomized trials in 7,179 non-diabetic adults with obesity ranked the options against placebo [13]:
| Treatment | Mean difference vs placebo |
|---|---|
| Tirzepatide, maximum tolerated dose | -20.90% (95% CI -24.93 to -16.87) |
| Tirzepatide 15 mg | -18.08% (95% CI -20.38 to -15.78) |
| Tirzepatide 10 mg | -14.93% (95% CI -17.23 to -12.63) |
| Semaglutide, maximum tolerated dose | -14.40% (95% CI -19.82 to -8.98) |
| Semaglutide 2.4 mg | -11.78% (95% CI -13.91 to -9.64) |
| Tirzepatide 5 mg | -11.49% (95% CI -14.65 to -8.34) |
Note the overlap: tirzepatide 5 mg and semaglutide 2.4 mg land in the same territory. Note also that the same analysis found the highest odds of stopping for side effects in the two maximum-tolerated-dose arms — odds ratio 7.36 for semaglutide and 5.56 for tirzepatide. Bigger effect, more people quitting.
How much of the weight lost is fat?
About three quarters, based on the one sub-study that measured it. In 160 SURMOUNT-1 participants scanned at baseline and week 72, fat mass fell 33.9% and lean mass fell 10.9% on tirzepatide, against 8.2% and 2.6% on placebo. Roughly 75% of the weight lost was fat and 25% was lean tissue — in both groups [14].
Lean mass includes water, organs and connective tissue, not just muscle, and 160 people is a small sample. But the fact that the ratio matched placebo argues against the drug being uniquely hard on muscle.
What should you do with these numbers?
Treat them as a map of what has been observed in groups, not a forecast for one person. In SURMOUNT-1, the same 15 mg dose that averaged 20.9% produced far more than that in some people and far less in others. In a follow-up analysis, 18% of participants had lost under 5% at week 12 — and 90% of those slow starters still reached 5% or more by week 72, averaging 11.0% total [15].
Whether this drug is appropriate for any particular person, and at what dose, is a decision for a healthcare provider who knows their medical history.
Sources
- SURMOUNT-1, New England Journal of Medicine 2022 — https://pubmed.ncbi.nlm.nih.gov/35658024/
- Zepbound NDA 217806 statistical review, FDA — https://www.accessdata.fda.gov/drugsatfda_docs/nda/2024/217806Orig1s000StatR.pdf
- SURMOUNT-2, The Lancet 2023 — https://pubmed.ncbi.nlm.nih.gov/37385275/
- SURMOUNT-3, Nature Medicine 2023 — https://pubmed.ncbi.nlm.nih.gov/37840095/
- SURMOUNT-5, New England Journal of Medicine 2025 — https://pubmed.ncbi.nlm.nih.gov/40353578/
- REDEFINE 4 headline results, Novo Nordisk 2026-02-23 — https://www.globenewswire.com/de/news-release/2026/02/23/3242381/0/en/Novo-Nordisk-A-S-CagriSema-demonstrated-23-weight-loss-in-an-open-label-head-to-head-REDEFINE-4-trial-in-people-with-obesity-the-primary-endpoint-was-not-achieved.html
- SURMOUNT-J, The Lancet Diabetes & Endocrinology 2025 — https://pubmed.ncbi.nlm.nih.gov/40031941/
- SURMOUNT-CN, JAMA 2024 — https://pubmed.ncbi.nlm.nih.gov/38819983/
- Truveta comparative effectiveness cohort, Journal of Endocrinological Investigation 2026 — https://pubmed.ncbi.nlm.nih.gov/41661445/
- GLP-1 persistence trends, Journal of Managed Care & Specialty Pharmacy 2026 — https://pubmed.ncbi.nlm.nih.gov/41760566/
- SURMOUNT-1 three-year prediabetes analysis, New England Journal of Medicine 2025 — https://pubmed.ncbi.nlm.nih.gov/39536238/
- SURMOUNT-MAINTAIN, The Lancet 2026 — https://pubmed.ncbi.nlm.nih.gov/42119587/
- Tirzepatide versus semaglutide network meta-analysis, Cureus 2025 — https://pubmed.ncbi.nlm.nih.gov/40978842/
- SURMOUNT-1 DXA body composition sub-study, Diabetes Obesity and Metabolism 2025 — https://pubmed.ncbi.nlm.nih.gov/39996356/
- SURMOUNT-1 early versus late responder analysis, Diabetes Obesity and Metabolism 2025 — https://pubmed.ncbi.nlm.nih.gov/40677091/
Questions people ask
What is the average weight loss on Zepbound?
In SURMOUNT-1, the registration trial in 2,539 adults with obesity and no diabetes, mean weight change at 72 weeks was 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg, compared with 3.1% on placebo. In US medical records outside of a trial, six-month weight loss averaged about 11%.
How much weight is 20% of body weight?
For someone starting at 220 pounds, 20% is 44 pounds. SURMOUNT-1 participants started at an average of about 105 kg, or 231 pounds, and the 15 mg group lost an average of about 22 kg, or 48 pounds, over 72 weeks.
Do people with diabetes lose less weight on tirzepatide?
Yes, consistently. In SURMOUNT-2, adults with type 2 diabetes lost 12.8% on 10 mg and 14.7% on 15 mg, compared with about 19.5% and 20.9% for the same doses in people without diabetes in SURMOUNT-1. Semaglutide shows the same pattern.
How does Zepbound compare with Wegovy in a head-to-head trial?
SURMOUNT-5 randomized 751 adults with obesity and no diabetes to tirzepatide or semaglutide 2.4 mg for 72 weeks. Weight change was 20.2% versus 13.7%. Waist circumference fell 18.4 cm versus 13.0 cm. The trial was open-label, meaning everyone knew which drug they were getting, which is a recognized limitation.
What percentage of people lose 20% or more on Zepbound?
In SURMOUNT-1, 50% of the 10 mg group and 57% of the 15 mg group lost at least 20% of their body weight at 72 weeks, compared with 3% on placebo.
Why do different sources give different weight-loss numbers for the same trial?
Usually because of estimands — different statistical rules for handling people who stop the drug. The treatment-regimen approach counts everyone who was randomized. The efficacy approach estimates what would happen if everyone stayed on treatment. The second number is always larger. REDEFINE 4, for example, reported tirzepatide at both 25.5% and 23.6% for the same result.
Is real-world weight loss on Zepbound lower than in trials?
Yes. A US electronic health record study of 1,003 tirzepatide patients found 11.15% average weight loss at six months. Trial participants get structured lifestyle counseling, free medication and close follow-up, and fewer than half of real-world patients reach the higher doses.
Does weight loss keep going past 72 weeks?
In the SURMOUNT-1 prediabetes extension, average weight loss at 176 weeks was 12.3% on 5 mg, 18.7% on 10 mg and 19.7% on 15 mg. That is close to, but slightly below, the 72-week figures, meaning most people held their loss rather than continuing to lose.
This article summarizes FDA labeling, published research and company information current as of September 14, 2026. It is not medical advice and does not replace a conversation with your own healthcare provider. How we research and verify.