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Zepbound before and after stories often feature very large losses, and the trials help explain why. In SURMOUNT-1, a 72-week study of adults with obesity or overweight and no diabetes, average weight fell 15.0% to 20.9% depending on the maintenance strength, compared with 3.1% on placebo, according to the Zepbound prescribing information (revised August 2026). At the highest strength, 56.7% of people lost at least 20% of their starting weight. Averages still hide a wide range: about 9% on the highest strength did not reach a 5% loss, people with type 2 diabetes lost less, and weight came back when people were switched to placebo. Zepbound is the weight-management brand of tirzepatide; Mounjaro, the same molecule, is approved for type 2 diabetes.
Peptide Labs does not sell Zepbound, Mounjaro or any prescription drug, and this page shows no patient photos or testimonials. It summarizes FDA labels and published trials. For averages across the whole GLP-1 class, see our overview of GLP-1 trial results.
Key Takeaways
- SURMOUNT-1: average weight change of -15.0% to -20.9% at 72 weeks versus -3.1% on placebo.
- On the highest strength, 83.5% lost at least 10% and 56.7% lost at least 20% of starting weight.
- Adults with type 2 diabetes lost less: -12.8% to -14.7% in SURMOUNT-2.
- In the head-to-head SURMOUNT-5 trial, tirzepatide averaged -20.2% versus -13.7% for semaglutide.
- Loss slowed and neared a plateau by week 72.
- People switched to placebo in SURMOUNT-4 regained 14.0% over the following year.
Zepbound before and after: what SURMOUNT-1 found
SURMOUNT-1 enrolled 2,539 adults with obesity, or overweight plus a weight-related condition, and no diabetes. Their average age was 45, 68% were women, and the average starting weight was 104.8 kg (about 231 pounds). Participants were assigned to one of three fixed maintenance strengths of weekly tirzepatide or placebo, alongside counseling on a reduced-calorie diet and physical activity. The trial was funded by Eli Lilly and published in the New England Journal of Medicine in 2022.
| Result at week 72 | Placebo | Lowest strength | Middle strength | Highest strength |
|---|---|---|---|---|
| Average weight change | -3.1% | -15.0% | -19.5% | -20.9% |
| Lost at least 5% | 34.5% | 85.1% | 88.9% | 90.9% |
| Lost at least 10% | 18.8% | 68.5% | 78.1% | 83.5% |
| Lost at least 15% | 8.8% | 48.0% | 66.6% | 70.6% |
| Lost at least 20% | 3.1% | 30.0% | 50.1% | 56.7% |
| Waist change | -4.0 cm | -14.0 cm | -17.7 cm | -18.5 cm |
The label figures above include everyone randomized, with missing weights estimated. The journal paper adds that 15%, 32% and 36% of people on the three strengths lost at least 25%, versus 1.5% on placebo. Among people who stayed on the medicine, the highest strength averaged a 22.5% loss, about 23.6 kg (52 pounds). The label notes that weight fell regardless of age, sex, race, ethnicity, starting BMI and blood sugar status.
Tirzepatide results in the other SURMOUNT trials
- SURMOUNT-2 (type 2 diabetes). In 938 adults with diabetes, average weight change was -12.8% and -14.7% on two strengths versus -3.2% on placebo, and 21.5% and 30.8% lost at least 20%.
- SURMOUNT-3 (after a diet program). 579 adults who had already lost at least 5% (6.9% on average) in a 12-week intensive lifestyle program lost a further 18.4% on tirzepatide over 72 weeks, while the placebo group regained 2.5%.
- SURMOUNT-4 (staying on versus stopping). People lost 20.9% on average during 36 weeks of open-label tirzepatide. Over the next 52 weeks, those who continued lost another 5.5%, while those switched to placebo regained 14.0%.
- Sleep apnea trials. In two 52-week trials in adults with obesity and moderate to severe obstructive sleep apnea, weight fell 17.7% and 19.6% versus 1.6% and 2.3% on placebo; see our guide to tirzepatide for sleep apnea.
Mounjaro results in type 2 diabetes
Mounjaro results come from diabetes trials, and Mounjaro is not approved for weight management. In the Mounjaro label’s 40-week trial of 1,879 adults with type 2 diabetes taking metformin, average weight change was -7.6, -9.3 and -11.2 kg on three tirzepatide strengths, compared with -5.7 kg on the diabetes strength of semaglutide. Our comparison of Mounjaro and Zepbound explains how the two brands differ.
Zepbound compared with semaglutide in SURMOUNT-5
SURMOUNT-5 was the first head-to-head obesity trial of the two molecules. It randomized 751 adults with obesity and no diabetes to the maximum tolerated strength of tirzepatide or of semaglutide for 72 weeks. Average weight change was -20.2% with tirzepatide and -13.7% with semaglutide, and waist size fell by 18.4 cm versus 13.0 cm. More people on tirzepatide reached the 10%, 15%, 20% and 25% thresholds. The trial was open-label, meaning participants knew which drug they were taking, and it was funded by Eli Lilly, which makes tirzepatide. Our article on the two molecules compared covers the wider evidence, and our sibling guide to Ozempic before and after results looks at semaglutide alone.
The timeline: when changes show
The labels describe raising the strength gradually over several months to limit stomach side effects, so the effect builds over time. In SURMOUNT-1, average weight kept falling for most of the 72 weeks; the authors wrote that the lowest-strength group reached a plateau and the two higher-strength groups were near a plateau by the end. In SURMOUNT-4, most of the loss happened in the first 36 weeks. Our guide to how long GLP-1 medicines take to work covers Zepbound timing as well.
What changes besides the number on the scale
- Body composition. The Zepbound label says tirzepatide lowers body weight with greater fat mass loss than lean mass loss. In a SURMOUNT-1 body-scan substudy, about 75% of the weight lost was fat and 25% lean mass, a split similar to diet-based weight loss; see what the scans show about muscle.
- Blood pressure and blood sugar. Systolic blood pressure fell by about 6.6 to 7.7 mmHg versus 1.0 on placebo, and more than 95% of participants with prediabetes had normal blood sugar levels at week 72, compared with 62% on placebo.
- Side effects. Nausea, diarrhea and other stomach effects were most common, mostly while the strength was being raised. Adverse events led 4.3% to 7.1% of participants to stop, versus 2.6% on placebo; see the label’s side-effect rates.
Reading before and after photos with a critical eye
Online photos are selected for impact and can be changed by lighting, posture, clothing and editing. They rarely show the starting weight, the time span or other changes such as surgery or new medicines, and some involve compounded or online products rather than the FDA-approved medicine; see our guide to compounded tirzepatide and semaglutide. Under the Federal Trade Commission’s endorsement guides, an ad showing one person’s result is likely to be read as typical, so advertisers need evidence for that or must disclose what people generally achieve. Trials also show that not everyone stays on: in SURMOUNT-1, 14.3% to 16.4% stopped the medicine early, compared with 26.4% on placebo.
Frequently Asked Questions
What do realistic Zepbound before and after results look like?
In SURMOUNT-1, average weight fell 15.0% to 20.9% over 72 weeks, depending on the strength, versus 3.1% on placebo. On the highest strength, 56.7% lost at least 20%.
How long does it take to see a difference on Zepbound?
Weight falls gradually as the strength is raised over several months. In SURMOUNT-1, loss continued for most of the 72 weeks before approaching a plateau.
Are tirzepatide results better than semaglutide results?
In the open-label, Lilly-funded SURMOUNT-5 trial, tirzepatide averaged -20.2% versus -13.7% for semaglutide at 72 weeks. Individual responses vary.
What are typical Mounjaro results?
Mounjaro is approved for type 2 diabetes. In its 40-week label trial, average weight change was -7.6 to -11.2 kg, depending on the strength.
Does everyone lose weight on Zepbound?
No. About 9% on the highest strength and 15% on the lowest did not reach a 5% loss in SURMOUNT-1, and people with type 2 diabetes lost less on average.
What happens after stopping Zepbound?
In SURMOUNT-4, people switched to placebo regained 14.0% of body weight over a year, while those who continued lost another 5.5%. Talk to a prescriber before stopping.
Peptide Labs does not sell GLP-1 medicines or any prescription drug. This article is general information, not medical advice. Read the Medication Guide that comes with a prescription, and ask a pharmacist or prescriber how this information applies to you.
Last reviewed October 2026.
Related guides: GLP-1 for Weight Loss: What the Trials Actually Showed, Mounjaro vs Zepbound: Same Tirzepatide, Different Approvals, Zepbound Side Effects: What the Latest Zepbound Label Reports.