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Zepbound Weight Loss Results: SURMOUNT-1 Dose-Stratified Data

Zepbound weight loss results by dose from SURMOUNT-1: 5mg 15%, 10mg 19.5%, 15mg 20.9% at 72 weeks, plus milestone responder rates and SURMOUNT-2/4/5 data.

Zepbound KwikPen autoinjector on a clinical surface with a measuring tape and weight scale in soft teal lighting.

Zepbound Clinical Outcomes

Zepbound Weight Loss Results: SURMOUNT-1 Dose-Stratified Data

Zepbound weight loss results from SURMOUNT-1, the FDA-approval anchor trial, came in at 15.0% (5mg), 19.5% (10mg), and 20.9% (15mg) mean body weight reduction over 72 weeks in 2,539 adults with obesity. This page walks through the dose-by-dose data, the percentage of patients who hit each milestone, and how the obesity-only outcomes (SURMOUNT-1) compare to the type 2 diabetes population (SURMOUNT-2) and the head-to-head data versus semaglutide (SURMOUNT-5).

For compound-wide context across all tirzepatide brands, see the compound-level tirzepatide weight loss data. For the patient-journey calendar of dosing weeks, see the Zepbound dosing schedule. This page is part of the complete tirzepatide guide.

Key Takeaways

  • SURMOUNT-1 (n=2,539, 72 weeks) mean body weight loss by dose: 15.0% on 5mg, 19.5% on 10mg, 20.9% on 15mg. Placebo arm lost roughly 3.1%.
  • Per-dose ≥5% responder rates: 85.1% on 5mg, 88.9% on 10mg, 90.9% on 15mg, versus 34.5% on placebo (Lilly HCP clinical data page).
  • 57% of 15mg patients lost at least 20% of body weight over 72 weeks, a threshold previously associated with bariatric surgery outcomes.
  • SURMOUNT-2 (type 2 diabetes population, 15mg): 13.4% mean body weight reduction at 72 weeks. Smaller magnitude than obesity-only SURMOUNT-1, still clinically meaningful.
  • SURMOUNT-4 maintenance data: patients continuing tirzepatide lost an additional 5.5% during a 52-week extension; patients switched to placebo regained a mean of 14.0% body weight.
  • SURMOUNT-5 head-to-head (vs semaglutide, 72 weeks): tirzepatide 20.2% mean loss vs semaglutide 13.7%; 32% of the tirzepatide arm reached the ≥25% threshold versus 16% on semaglutide.

20.9%

Mean body weight loss at 15mg, 72 weeks (SURMOUNT-1)

57%

Of 15mg patients lost at least 20% of body weight

90.9%

Of 15mg patients hit the ≥5% responder threshold

2,539

Adults enrolled in SURMOUNT-1 anchor trial

What Does Zepbound Achieve? The SURMOUNT-1 Trial in 3 Numbers

SURMOUNT-1 is the pivotal trial that earned Zepbound its FDA approval for chronic weight management in November 2023. The trial enrolled 2,539 adults with obesity (BMI of 30 or above), or with overweight (BMI 27 to 30) plus at least one weight-related comorbidity, and randomized them across three tirzepatide dose arms and a placebo arm. Importantly, SURMOUNT-1 excluded participants with type 2 diabetes; that population was studied separately in SURMOUNT-2.

The primary endpoint was the percentage change in body weight from baseline at week 72, roughly 17 months of weekly subcutaneous injection. The three headline numbers from the New England Journal of Medicine publication: 15.0% mean body weight loss at 5mg, 19.5% at 10mg, and 20.9% at 15mg. The placebo arm lost about 3.1% over the same period, which is the typical attrition-adjusted result for a structured lifestyle intervention arm in obesity trials.

Dose-Stratified Results Table

The combined table below pairs the SURMOUNT-1 mean body weight reduction with the per-dose responder rates published on the Lilly HCP clinical data page. For absolute pound figures, the trial's mean baseline body weight was roughly 230 lbs; absolute lb conversions use a 200-lb reference person for round-number readability.

Dose Mean Weight Loss Mean lbs (200 lb person) ≥5% Responders ≥20% Responders
5 mg 15.0% 30 lbs 85.1% N/R
10 mg 19.5% 39 lbs 88.9% N/R
15 mg 20.9% 42 lbs 90.9% 57%
Placebo ~3.1% 6 lbs 34.5% N/R

Sources: SURMOUNT-1 (Jastreboff et al., NEJM 2022) for mean weight loss; zepbound.lilly.com/hcp/clinical-data-weight for per-dose ≥5% responder rates. N/R = not reported at this dose granularity in primary publications.

SURMOUNT-1 bar chart of Zepbound weight loss: 15% on 5mg, 19.5% on 10mg, 20.9% on 15mg.

Mean body weight reduction at 72 weeks across the three SURMOUNT-1 tirzepatide arms. Higher doses produced incrementally greater mean loss with diminishing returns above 10mg.

Track Your Zepbound Progress Week by Week

Pick your starting weight, planned titration pace, and target dose. The free pharmacokinetic calculator plots tirzepatide accumulation across the full schedule and lets you log weight against the trial averages so you can see how your trajectory compares to SURMOUNT-1.

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Zepbound Weight Loss Results by Milestone: What Percentage of Patients Hit Each Target?

Mean percentages tell only half the story. The other half is the distribution: of all the patients on a given dose, how many crossed each meaningful weight-loss threshold. This is the question most patients are actually asking when they look up Zepbound: "if I take the maximum dose, what is the chance I lose 20% of my body weight?" The SURMOUNT-1 responder data answer that directly.

At the 15mg arm over 72 weeks, roughly 91% of participants lost at least 5% of body weight, 57% lost at least 20%, and the trial reported meaningful counts of patients crossing the 25% threshold as well. For a 200-lb starting weight, those thresholds translate to 10 lbs (5%), 30 lbs (15%), 40 lbs (20%), and 50 lbs (25%). For a 250-lb starting weight, the same percentages translate to 12.5 lbs, 37.5 lbs, 50 lbs, and 62.5 lbs respectively.

The "Surgery-Level" 20% Threshold

The 20% body weight loss threshold matters because it sits in the range historically achieved by bariatric surgery. Sleeve gastrectomy and Roux-en-Y gastric bypass typically produce mean weight reductions of 25 to 30% at one year. SURMOUNT-1's 15mg arm reporting 57% of participants crossing the 20% threshold was the result that put tirzepatide into the same conversation as surgery for obesity medicine. The mean for the 15mg arm (20.9%) brushed against that threshold; the responder distribution showed it was not a fluke of averages.

The 25% Threshold (SURMOUNT-5 Head-to-Head)

The ≥25% responder rate at the maximum tirzepatide dose was further characterized in SURMOUNT-5, the 2025 head-to-head trial against semaglutide in adults with obesity. In SURMOUNT-5, 32% of the tirzepatide arm reached ≥25% body weight loss at 72 weeks, compared with 16% of the semaglutide arm. SURMOUNT-5 was funded by Eli Lilly, the manufacturer of tirzepatide; the trial design was reviewed and the primary results published in the New England Journal of Medicine.

Zepbound Weight Loss Results in Type 2 Diabetes (SURMOUNT-2)

SURMOUNT-1 excluded participants with type 2 diabetes, which made interpretation of "what should I expect on Zepbound" cleaner for the obesity indication but left an open question for the very common scenario of obesity plus T2D. SURMOUNT-2 was the follow-on trial designed to answer that question.

SURMOUNT-2 enrolled adults with both obesity and type 2 diabetes and reported the 15mg arm produced a mean 13.4% body weight reduction at 72 weeks. That is meaningful weight loss but materially less than the 20.9% mean from the obesity-only SURMOUNT-1 population. The pattern is consistent across the GLP-1 receptor agonist class: weight loss tends to be lower in patients with T2D than in patients with obesity alone, likely because diabetes alters the metabolic context in which appetite reduction translates into fat loss.

SURMOUNT-1 vs SURMOUNT-2 at the 15mg Arm

Trial Population 15mg Mean Weight Loss Duration
SURMOUNT-1 Obesity, no T2D 20.9% 72 weeks
SURMOUNT-2 Obesity + Type 2 Diabetes 13.4% 72 weeks

One important regulatory note: Zepbound is FDA-approved for obesity, not for type 2 diabetes. The tirzepatide molecule is the same in both brands, but the T2D indication is held by Mounjaro. Patients with both conditions typically receive Mounjaro under the T2D label; physicians may prescribe across labels at their discretion under standard practice.

SURMOUNT-1 responder rates on 15mg Zepbound: 91% lost over 5%, 57% lost over 20%.

SURMOUNT-1 responder rates at the 15mg dose. The ≥20% threshold sits in territory previously associated with bariatric surgery outcomes.

Week-by-Week Pace: When Do Zepbound Results Appear?

The 20.9% headline is the result at week 72, not week 12. The pace of weight loss across the 72-week trial was uneven by design, because the dose itself is built up over the first 16 to 20 weeks rather than being given at full strength from day one. A rough timeline based on the SURMOUNT-1 trajectory and the FDA-mandated titration schedule:

  • Weeks 1 to 4 (2.5mg starter): the gastrointestinal adaptation phase. Weight loss is minimal and not the goal of this phase; the goal is tolerability.
  • Weeks 5 to 12 (5mg first therapeutic dose): the first dose that produces meaningful loss. SURMOUNT-1 participants on active doses typically reached roughly 6 to 8% loss by the 12-week mark.
  • Weeks 13 to 36 (escalation through 10mg or 12.5mg): the steepest part of the curve for most patients. Typical loss at the 6-month mark falls in the 10 to 16% range for those reaching the higher doses on schedule.
  • Weeks 52 to 72 (maintenance): the loss curve flattens. The maximum mean values (15.0%, 19.5%, 20.9%) are the 72-week endpoint, not a moving plateau.

For the full patient-journey calendar covering each step, the maintenance decision points, and missed-dose rules, see the Zepbound dosing schedule. The schedule page covers the timeline; this page covers the outcomes that the timeline produces.

Long-Term Maintenance: What Happens After 72 Weeks (SURMOUNT-4)

SURMOUNT-4 was designed to answer the question of what happens to weight after the 72-week SURMOUNT-1 endpoint. The trial took patients who had completed an open-label tirzepatide lead-in and then randomized them to either continue tirzepatide for an additional 52 weeks or switch to placebo while keeping the same lifestyle support.

The results were directional and consistent with the GLP-1 class. Patients who continued tirzepatide lost an additional 5.5% body weight during the 52-week extension period. Patients who switched to placebo regained a mean of 14.0% body weight over the same 52 weeks. The framing this produces is straightforward: tirzepatide manages an underlying biology, and the biology returns when the medication stops, similar to how blood pressure medication manages blood pressure as long as it is taken.

Chronic Condition, Chronic Treatment

The FDA label does not define an upper time limit on Zepbound treatment. The drug is approved for chronic weight management, meaning treatment continues as long as the medical indication is met. SURMOUNT-4 is the trial evidence that the weight-loss benefit persists with continued treatment and reverses substantially when treatment is discontinued.

Real-World Outcomes vs Trial Outcomes

The SURMOUNT-1 averages are derived from a controlled trial with structured support, regular study visits, and high adherence by design. Real-world outcomes commonly fall short of the trial averages, and a handful of factors explain most of the gap.

  • Adherence: SURMOUNT-1 had high study-protocol adherence; real-world weekly injection adherence is materially lower, especially during the titration phase when nausea is most prominent.
  • Dose reached: not every patient tolerates 15mg, and some plateau at 5mg or 10mg by choice or by side-effect burden. Mean real-world weight loss therefore weights toward the lower-dose arms.
  • Lifestyle co-interventions: SURMOUNT-1 included structured nutrition and physical activity counseling; the typical community prescription comes with less intensive lifestyle support.
  • Individual metabolic variation: response distributions are wide. Some patients exceed the trial mean; some fall well below it. Genetic factors, baseline metabolic rate, and prior weight history all contribute.

Video: Tirzepatide Dosing and Clinical Outcomes Overview

A clinical walkthrough of tirzepatide dosing and the outcomes data underlying the FDA approval. The medication discussed is the same molecule as Zepbound; the dose-response relationship and the SURMOUNT-1 results apply identically.

Comparing Zepbound Weight Loss Results to Other GLP-1 Medications

The cleanest comparison is SURMOUNT-5, the 2025 head-to-head trial of tirzepatide versus semaglutide in adults with obesity. SURMOUNT-5 enrolled 751 participants and ran for 72 weeks. The tirzepatide arm reached a mean 20.2% body weight reduction; the semaglutide arm reached 13.7%. At the ≥25% threshold, 32% of tirzepatide patients hit the mark versus 16% of semaglutide patients. SURMOUNT-5 was funded by Eli Lilly.

For broader context, the STEP 1 trial of semaglutide 2.4mg weekly (the dose Wegovy uses) reported a mean 14.9% body weight reduction at 68 weeks in adults with obesity. The SURMOUNT-5 head-to-head and the indirect comparison through STEP 1 both place tirzepatide at the higher end of the current weight-loss medication class. For full side-by-side detail on dose schedules, mechanism, side effects, and cost, see the Zepbound vs Wegovy comparison and the tirzepatide vs semaglutide deep dive.

Frequently Asked Questions About Zepbound Weight Loss Results

How much weight can you lose on Zepbound in a month?

In SURMOUNT-1, Zepbound users on the 15mg dose lost an average of 20.9% of body weight over 72 weeks. Averaged across the full trial that works out to roughly 3 to 5 pounds per month, but the pace is uneven by design: slower during the first 4 to 5 months of titration, faster from months 3 to 12 once therapeutic doses are reached, and slower again as the curve plateaus toward week 72.

What percentage of people on Zepbound lose 20% or more of their body weight?

In SURMOUNT-1, 57% of participants on the 15mg dose lost at least 20% of body weight over 72 weeks. That puts more than half of high-dose trial completers in a range that was previously associated almost exclusively with bariatric surgery outcomes. The 5mg and 10mg arms did not have a ≥20% responder rate individually reported in the primary publication.

How does Zepbound weight loss compare to Wegovy?

In SURMOUNT-5, the 72-week head-to-head trial in adults with obesity, Zepbound users lost an average of 20.2% of body weight versus 13.7% for Wegovy users. 32% of the Zepbound group lost at least 25% of body weight compared with 16% of the Wegovy group. SURMOUNT-5 was funded by Eli Lilly; the primary results were published in the New England Journal of Medicine in 2025.

What are Zepbound results at 3 months?

By 3 months (around week 12 of the trial), SURMOUNT-1 participants on active doses had typically lost roughly 6 to 8% of body weight. The 3-month mark sits inside the titration phase, when the first therapeutic dose (5mg) has just been reached, so the trajectory steepens after that point and continues building through 72 weeks. The 20.9% headline is the 72-week endpoint, not the 3-month checkpoint.

Can you lose 70 pounds on Zepbound?

Yes, it is possible for some individuals. A person starting at 335 pounds who reaches the 15mg arm's 20.9% mean weight reduction would lose roughly 70 pounds. Lilly reported the SURMOUNT-1 15mg arm lost an average of 48 lbs in absolute terms, against a trial-wide mean baseline weight near 230 lbs. Individual outcomes depend heavily on starting weight, dose reached, and adherence. Higher starting weights produce larger absolute pound losses at the same percentage.

How long does it take to lose 40 pounds on Zepbound?

For someone starting around 200 pounds, losing 40 pounds (20% of body weight) corresponds to the mean 15mg outcome at 72 weeks, roughly 17 to 18 months. Patients starting at higher weights reach the 40-pound milestone faster in calendar time because the percentage loss is similar but the absolute pounds are greater. Many patients report hitting 40 pounds between months 10 and 18 depending on starting weight, dose reached, and adherence.

How do Zepbound results differ by dose?

In SURMOUNT-1, mean body weight loss at 72 weeks was 15.0% on 5mg, 19.5% on 10mg, and 20.9% on 15mg. Per-dose ≥5% responder rates from the Lilly HCP clinical data page were 85.1%, 88.9%, and 90.9% respectively, against 34.5% for placebo. Higher doses produced larger mean loss with diminishing returns above 10mg; even the 5mg arm substantially outperformed placebo and most other weight-loss interventions.

What happens if you stop taking Zepbound?

SURMOUNT-4 showed that participants who stopped tirzepatide after achieving weight loss regained a mean of 14.0% of body weight within 52 weeks, while those who continued treatment lost an additional 5.5%. This is consistent with the obesity-as-chronic-condition framing: the medication manages an underlying biology while taken, and the biology returns when treatment stops. The FDA label does not define an upper time limit on treatment.

Are Zepbound results as good for people with type 2 diabetes?

Results are meaningful but smaller in magnitude. In SURMOUNT-2, which enrolled adults with both obesity and type 2 diabetes, the 15mg dose produced approximately 13.4% mean body weight reduction at 72 weeks, compared with 20.9% in the obesity-only SURMOUNT-1 population. The pattern is consistent across the GLP-1 class. Zepbound is FDA-approved for obesity (non-T2D indication); patients with T2D typically use Mounjaro, which is the same tirzepatide molecule under a different label.

Does the Zepbound calculator project future weight loss?

GLP3Planner's free Zepbound calculator models pharmacokinetic drug levels and tracks your actual weight against your injection dates and doses. It does not project a personal future weight loss number, because individual outcomes vary widely from the trial means. The tool is designed to visualize active drug levels and log progress against the SURMOUNT-1 averages, not to promise a specific outcome.

Compare Your Trajectory to SURMOUNT-1

Enter your starting weight, dose schedule, and weekly weigh-ins. The free Zepbound weight loss calculator plots your trajectory against the trial averages so you can see how your real-world response compares to the 5mg, 10mg, and 15mg SURMOUNT-1 arms.

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References

  1. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387(3):205-216. DOI: 10.1056/NEJMoa2206038. PMID: 35658024. (SURMOUNT-1 anchor trial: n=2,539, 72 weeks, 15.0% at 5mg, 19.5% at 10mg, 20.9% at 15mg, 57% ≥20% responder rate at 15mg.)
  2. Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. 2023;402(10402):613-626. DOI: 10.1016/S0140-6736(23)01200-X. PMID: 37385275. (Obesity + T2D population, 15mg arm: 13.4% mean body weight reduction at 72 weeks.)
  3. Aronne LJ, Sattar N, Horn DB, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial. JAMA. 2024;331(1):38-48. DOI: 10.1001/jama.2023.24948. PMID: 38261398. (Continued treatment +5.5% additional loss; withdrawal arm +14.0% regain over 52 weeks.)
  4. Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). New England Journal of Medicine. 2025;393:26-36. DOI: 10.1056/NEJMoa2416394. (Head-to-head: tirzepatide 20.2% vs semaglutide 13.7% at 72 weeks; 32% vs 16% reaching ≥25% loss.)
  5. Eli Lilly and Company. Zepbound (tirzepatide) Clinical Data, Safety & Study Design. zepbound.lilly.com/hcp/clinical-data-weight. Accessed 2026-05-26. (Per-dose ≥5% responder rates: 85.1% at 5mg, 88.9% at 10mg, 90.9% at 15mg, 34.5% placebo.)

Medical Disclaimer

This article is for informational purposes only and does not constitute medical advice. All trial outcomes, responder rates, and dose-specific values on this page reflect the SURMOUNT trial program (SURMOUNT-1, SURMOUNT-2, SURMOUNT-4, SURMOUNT-5) and the Lilly HCP clinical data page as cited in the references section. Individual results vary substantially from trial means. Zepbound is FDA-approved for chronic weight management in adults with obesity, not for type 2 diabetes; the T2D indication is held by Mounjaro. Always consult your prescribing clinician about treatment goals, dose selection, and continuation. GLP3Planner is an informational and calculation tool, not a medical service.

More Zepbound and Tirzepatide Guides on GLP3Planner