How Much Weight Do You Lose on Zepbound? Trial Results by Dose
In the main 72-week trial, adults without diabetes lost an average of 15.0% on 5 mg, 19.5% on 10 mg, and 20.9% on 15 mg of Zepbound, versus 3.1% on placebo. Losses ran smaller with type 2 diabetes and in real-world data.
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In the main approval trial, adults with obesity but without diabetes lost an average of 15.0% of their body weight on 5 mg of Zepbound, 19.5% on 10 mg, and 20.9% on 15 mg over 72 weeks, compared with 3.1% on placebo [1]. Those are group averages, and results vary from person to person. The numbers shift depending on the population studied: people with type 2 diabetes lost less (14.7% on 15 mg) [3], people in Japan and China lost somewhat different amounts [7][8], and real-world data at six months show smaller losses so far, around 11.15% for people who stayed on treatment [9].
Zepbound is the brand name for tirzepatide when it is prescribed for chronic weight management. Tirzepatide was previously approved in 2022 under the name Mounjaro for type 2 diabetes, and the weight-management application was built on two phase 3 trials, SURMOUNT-1 and SURMOUNT-2 [2]. Eli Lilly funded SURMOUNT-1, SURMOUNT-2, SURMOUNT-5, SURMOUNT-J, and SURMOUNT-MAINTAIN [1][3][5][7][12], as well as the real-world Truveta study [9].
What did SURMOUNT-1 find, dose by dose?
SURMOUNT-1 enrolled 2,539 adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related complication, and excluded people with diabetes. The trial ran 72 weeks, including a 20-week dose-escalation period. At the start, participants weighed 104.8 kg on average with a mean BMI of 38.0 [1].
Here are the week-72 results using the treatment-regimen estimand, which counts everyone randomized regardless of whether they stopped treatment [1]:
| Dose | Mean weight change at week 72 | Reached 5% loss |
|---|---|---|
| 5 mg | -15.0% | 85% |
| 10 mg | -19.5% | 89% |
| 15 mg | -20.9% | 91% |
| Placebo | -3.1% | 35% |
All comparisons with placebo were statistically significant [1]. Half of the 10 mg group and 57% of the 15 mg group lost at least 20% of their body weight, compared with 3% of the placebo group [1]. The FDA’s statistical review of the same data reported the difference from placebo as -16.4 percentage points for 10 mg (95% CI -17.9 to -14.8) and -17.8 points for 15 mg (95% CI -19.3 to -16.3). Week-72 data were missing for 10.5% of the 10 mg group, 9.4% of the 15 mg group, and 21.6% of the placebo group [2].
How much weight loss happens with type 2 diabetes?
SURMOUNT-2 studied 938 adults with a BMI of 27 or higher and HbA1c between 7% and 10%. They weighed 100.7 kg on average at baseline, with a mean BMI of 36.1, and were followed for 72 weeks [3].
At week 72, mean weight change was -12.8% on 10 mg and -14.7% on 15 mg, versus -3.2% on placebo. The estimated treatment differences were -9.6 and -11.6 percentage points. Between 79% and 83% of tirzepatide-treated participants lost at least 5% of their body weight, compared with 32% on placebo [3].
The contrast with SURMOUNT-1 is direct: the 15 mg dose produced -20.9% average loss in people without diabetes [1] and -14.7% in people with type 2 diabetes [3].
Does tirzepatide add to weight lost through a lifestyle program?
SURMOUNT-3 tested what happens when tirzepatide is added after a structured lifestyle effort. All 579 participants first went through a 12-week intensive lifestyle intervention, and only those who lost at least 5.0% of their weight were randomized to tirzepatide at the maximum tolerated dose (10 or 15 mg) or placebo for 72 weeks [4].
From the point of randomization, the tirzepatide group lost an additional 18.4% of body weight on average, while the placebo group gained 2.5%. The difference was -20.8 percentage points (95% CI -23.2 to -18.5). An additional 5% loss was achieved by 87.5% of the tirzepatide group versus 16.5% of the placebo group [4].
How does Zepbound compare with Wegovy head to head?
SURMOUNT-5 directly compared the two drugs in 751 adults with obesity but no type 2 diabetes. It was an open-label trial, meaning participants and investigators knew which drug they were taking, and it ran 72 weeks. The tirzepatide arm used the maximum tolerated dose of 10 or 15 mg; the semaglutide arm used 1.7 or 2.4 mg. Eli Lilly funded the trial [5].
At week 72, the tirzepatide group lost 20.2% of body weight on average (95% CI -21.4 to -19.1), versus 13.7% with semaglutide (95% CI -14.9 to -12.6). Waist circumference fell 18.4 cm with tirzepatide versus 13.0 cm with semaglutide. The tirzepatide arm was more likely to reach losses of at least 10%, 15%, 20%, and 25%. Gastrointestinal events were the most common side effects in both arms, mostly mild to moderate and occurring mainly during dose escalation [5].
How does tirzepatide compare with CagriSema?
Novo Nordisk announced headline results on February 23, 2026 from REDEFINE 4, an open-label 84-week trial in 809 adults with obesity plus at least one comorbidity, with a mean baseline weight of 114.2 kg. It compared CagriSema 2.4/2.4 mg with tirzepatide 15 mg [6].
These are company-announced headline results from Novo Nordisk. Under the efficacy estimand, which estimates the effect if everyone adhered to treatment, tirzepatide produced 25.5% weight loss versus 23.0% for CagriSema. Under the treatment-regimen estimand, which measures the effect regardless of whether people stop treatment, the figures were 23.6% versus 20.2%. CagriSema did not meet its primary endpoint of non-inferiority to tirzepatide on weight loss [6].
The treatment-regimen estimand is the same framework behind the headline SURMOUNT-1 figures, which count people regardless of stopping treatment [1][6].
What were the results in Japan and China?
SURMOUNT-J enrolled Japanese adults with a BMI of 27 or higher plus at least two obesity-related disorders, or 35 or higher plus at least one. The modified intention-to-treat population was 225 people, followed for 72 weeks and analyzed with the efficacy estimand [7].
The reported figures are placebo-adjusted differences, not raw weight change: at week 72, tirzepatide 10 mg beat placebo by 16.1 percentage points and 15 mg by 21.1 points. At least 5% weight loss was achieved by 94% of the 10 mg group and 96% of the 15 mg group, versus 20% on placebo [7].
SURMOUNT-CN enrolled 210 Chinese adults with a mean age of 36.1, mean weight of 91.8 kg, and mean BMI of 32.3, followed for 52 weeks. Mean weight change at week 52 was -13.6% on 10 mg, -17.5% on 15 mg, and -2.3% on placebo [8].
What do real-world numbers look like?
A study using Truveta US electronic health records followed 2,396 adults without diabetes who stayed on treatment, 1,003 on tirzepatide and 1,393 on semaglutide, starting between December 2023 and June 2024. Eli Lilly funded the study [9].
At six months, the tirzepatide group had lost 11.15% of body weight on average versus 8.83% with semaglutide, an adjusted difference of -2.32 percentage points (95% CI -3.17 to -1.48). Only 42.4% of tirzepatide users had reached a dose of 10 mg or higher, compared with 67.7% of semaglutide users at 1.7 mg or higher [9].
A separate analysis of Prime Therapeutics pharmacy claims covered 33,607 commercially insured adults without diabetes. One-year persistence, meaning no more than a 60-day treatment gap, was 64.0% for tirzepatide starters in 2023 and 64.8% in the first half of 2024. Semaglutide persistence was 39.8% in 2023 and 58.6% in the first half of 2024. Across all products, persistence was 33.2% in 2021 [10].
What happens after 72 weeks, or after lowering the dose?
A 176-week analysis of the SURMOUNT-1 participants who also had prediabetes, 1,032 people, found mean weight change of -12.3% on 5 mg, -18.7% on 10 mg, and -19.7% on 15 mg, versus -1.3% on placebo. By week 176, 1.3% of tirzepatide-treated participants had developed type 2 diabetes versus 13.3% on placebo [11].
SURMOUNT-MAINTAIN ran 112 weeks total. The 441 participants enrolled at study start weighed 113.8 kg on average. After a 60-week open-label period on the maximum tolerated dose, 378 participants were randomized to stay on their dose, drop to 5 mg, or switch to placebo [12].
At week 112, change from the original baseline was -21.9% for those who stayed on the maximum tolerated dose, -16.6% for those who dropped to 5 mg, and -9.9% for those who switched to placebo. Starting at week 84, participants could receive rescue tirzepatide if their weight regain exceeded 50% of lost weight; rescue therapy was received by 8% of the maximum-dose group (11 of 138), 25% of the 5 mg group (35 of 142), and 67% of the placebo group (60 of 90) [12].
How do the doses compare across multiple trials?
A network meta-analysis pooled eight randomized trials with 7,179 non-diabetic adults with obesity. It estimated differences versus placebo rather than raw weight change [13]:
| Treatment | Estimated difference vs placebo |
|---|---|
| Tirzepatide max tolerated dose | -20.90% |
| Tirzepatide 15 mg | -18.08% |
| Tirzepatide 10 mg | -14.93% |
| Semaglutide max tolerated dose | -14.40% |
| Semaglutide 2.4 mg | -11.78% |
| Tirzepatide 5 mg | -11.49% |
The same analysis found the highest odds of stopping treatment due to side effects with semaglutide at maximum tolerated dose (odds ratio 7.36) and tirzepatide at maximum tolerated dose (odds ratio 5.56) [13]. In SURMOUNT-1 itself, side effects led 4.3% of the 5 mg group, 7.1% of the 10 mg group, and 6.2% of the 15 mg group to stop treatment, versus 2.6% on placebo [1].
How much of the weight loss is fat versus lean mass?
A substudy of SURMOUNT-1 used DXA body scans at baseline and week 72 in 160 people, 124 on pooled tirzepatide doses and 36 on placebo [14].
With tirzepatide, total weight fell 21.3%, fat mass fell 33.9%, and lean mass fell 10.9%. With placebo, the changes were -5.3%, -8.2%, and -2.6%. About 75% of the weight lost was fat and about 25% was lean mass in both the tirzepatide and placebo groups, and those proportions stayed consistent across most subgroups, including sex, age, and amount of weight lost [14].
What if weight loss is slow in the first few months?
A post hoc analysis of SURMOUNT-1 looked at 1,545 tirzepatide-treated participants who took at least 75% of their assigned doses and had weight measurements at weeks 0, 12, 24, and 72. Of these, 278, or 18%, had lost less than 5% of their weight at week 12. These late responders were more often male (45% versus 30% among early responders) and heavier at baseline, 110.2 kg versus 103.6 kg [15].
Among those slow starters, 70% reached at least 5% loss by week 24 and 90% by week 72. Their mean time to reach 5% loss was 24.8 weeks. Higher doses were linked to higher proportions of people reaching weight-loss thresholds at weeks 24 and 72 [15].
All of these figures describe group averages from trials and observational data. Individual results vary, and decisions about starting, raising, or lowering a dose belong with a prescriber.
Sources
- PubMed. Tirzepatide once weekly for the treatment of obesity.
- US Food and Drug Administration. Statistical review and evaluation, clinical studies, NDA 217806, tirzepatide.
- PubMed. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial.
- PubMed. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial.
- PubMed. Tirzepatide as compared with semaglutide for the treatment of obesity.
- 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. February 23, 2026.
- PubMed. Efficacy and safety of once-weekly tirzepatide in Japanese patients with obesity disease (SURMOUNT-J): a multicentre, randomised, double-blind, placebo-controlled phase 3 trial.
- PubMed. Tirzepatide for weight reduction in Chinese adults with obesity: the SURMOUNT-CN randomized clinical trial.
- PubMed. Comparative effectiveness of tirzepatide and semaglutide for obesity management in US clinical practice: a 6-month retrospective cohort study.
- PubMed. Trends in 1-year persistence and adherence among initiators of high-potency, weight loss-indicated glucagon-like peptide 1 receptor agonists.
- PubMed. Tirzepatide for obesity treatment and diabetes prevention.
- PubMed. Tirzepatide for maintenance of bodyweight reduction in people with obesity in the USA (SURMOUNT-MAINTAIN): a multicentre, double-blind, randomised, placebo-controlled trial.
- PubMed. Comparative efficacy and tolerability of tirzepatide versus semaglutide at varying doses for weight loss in non-diabetic adults with obesity: a network meta-analysis of randomized controlled trials.
- PubMed. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight.
- PubMed. Weight reduction over time in tirzepatide-treated participants by early weight loss response: post hoc analysis in SURMOUNT-1.
Frequently asked questions
What is the average weight loss on Zepbound 15 mg?
In SURMOUNT-1, adults with obesity but no diabetes lost an average of 20.9% of body weight on 15 mg over 72 weeks, versus 3.1% on placebo. In people with type 2 diabetes, the 15 mg average was 14.7%, and in the head-to-head SURMOUNT-5 trial the tirzepatide arm, which included 15 mg, averaged 20.2%.
How much weight do people lose on Zepbound 5 mg?
In SURMOUNT-1, the 5 mg dose produced an average weight loss of 15.0% at week 72, with 85% of participants losing at least 5% of their body weight. In the 176-week prediabetes analysis, the 5 mg group averaged -12.3%. A network meta-analysis estimated the 5 mg difference versus placebo at -11.49 percentage points.
How much weight loss happens on Zepbound with type 2 diabetes?
In SURMOUNT-2, adults with obesity and type 2 diabetes lost an average of 12.8% on 10 mg and 14.7% on 15 mg over 72 weeks, versus 3.2% on placebo. Between 79% and 83% of tirzepatide users lost at least 5% of body weight, compared with 32% on placebo.
Which produces more weight loss, Zepbound or Wegovy?
In the 72-week open-label SURMOUNT-5 trial, tirzepatide at the maximum tolerated dose produced 20.2% average weight loss versus 13.7% for semaglutide at its maximum tolerated dose. Waist circumference fell 18.4 cm versus 13.0 cm, and the tirzepatide arm was more likely to hit every loss threshold from 10% to 25%.
How long does Zepbound take to reach 5% weight loss?
In a post hoc SURMOUNT-1 analysis of participants who took at least 75% of assigned doses, 82% had lost at least 5% by week 12. Among the 18% who had not, 70% reached 5% by week 24 and 90% by week 72, with a mean time to 5% loss of 24.8 weeks.
Why do real-world results differ from trial numbers?
The Truveta real-world study measured only six months and only people who stayed on treatment, finding 11.15% average loss on tirzepatide, versus 20.9% at 72 weeks in SURMOUNT-1. Only 42.4% of tirzepatide users in that study had reached 10 mg or higher, and claims data show 64.8% of tirzepatide starters in the first half of 2024 persisted for a year.
Does weight come back after lowering the Zepbound dose?
In SURMOUNT-MAINTAIN, participants who dropped from the maximum tolerated dose to 5 mg averaged -16.6% from their original baseline at week 112, versus -21.9% for those who stayed on the maximum dose and -9.9% for those switched to placebo. Rescue tirzepatide was received by 25% of the 5 mg group versus 8% of the maximum-dose group.
How much of the weight lost on Zepbound is muscle?
In a DXA substudy of SURMOUNT-1, about 25% of the weight lost was lean mass and about 75% was fat mass, in both the tirzepatide and placebo groups. Lean mass fell 10.9% with tirzepatide versus 2.6% with placebo, and the proportions were consistent across most subgroups.
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.