GLP-1 weight loss results vary widely by drug: in the pivotal trials, tirzepatide produced up to about 20.9% mean weight loss, semaglutide about 14.9%, and liraglutide about 8%, over roughly 12 to 18 months. Those are among the largest reductions ever recorded for weight-management medicines, but the figure you can expect depends on the drug, the dose, how long you stay on it, and whether you pair it with diet and activity. This page is a single reference for the average GLP-1 weight loss results by drug in 2026, drawn from the trials that earned each one its approval, so you can compare them side by side.
GLP-1 weight loss results by the numbers (2026)
- ~20.9%: mean weight loss with tirzepatide (15 mg) over 72 weeks in SURMOUNT-1, the highest recorded for an approved weight drug.
- ~14.9%: mean weight loss with semaglutide (2.4 mg) over 68 weeks in STEP-1.
- ~8%: mean weight loss with liraglutide (3 mg) over 56 weeks in SCALE.
- ~3x: how much more weight tirzepatide's top dose took off versus older liraglutide.
- Most of it returns: trials of stopping show much of the lost weight comes back, so results depend on continued use.
The GLP-1 results index: every drug, by trial
The table below is the core of this index. It lists each major GLP-1 (and dual GIP/GLP-1) medication, the trial program behind its results, the top studied dose, the mean weight loss reported, and the trial duration. Figures are trial averages; individual results vary, and weight-management doses differ from diabetes doses of the same molecule.
| Medication | Active ingredient | Pivotal trial | Top dose | Mean weight loss | Duration |
|---|---|---|---|---|---|
| Zepbound | Tirzepatide | SURMOUNT-1 | 15 mg | ~20.9% | 72 weeks |
| Mounjaro | Tirzepatide | SURMOUNT / SURPASS | 15 mg | ~15–21%* | 72 weeks |
| Wegovy | Semaglutide | STEP-1 | 2.4 mg | ~14.9% | 68 weeks |
| Ozempic | Semaglutide | SUSTAIN / STEP | 2.0 mg | ~6–15%* | 40–68 weeks |
| Saxenda | Liraglutide | SCALE | 3.0 mg | ~8% | 56 weeks |
| Rybelsus | Semaglutide (oral) | PIONEER | 14 mg | modest (diabetes dose) | 26–52 weeks |
| Compounded | Semaglutide / tirzepatide | mirrors branded molecule | varies | expected to track the brand | ongoing |
*Ranges reflect that the diabetes versions (Ozempic, Mounjaro) were studied largely in people with type 2 diabetes, where weight loss tends to be lower than in the dedicated obesity trials, and that results scale with dose. The single clearest pattern: the dual GIP/GLP-1 agonist tirzepatide leads, semaglutide follows, and the older liraglutide trails. We unpack that head-to-head in semaglutide versus tirzepatide.
GLP-1 results index
Average weight loss by drug
Mean weight loss in each drug's pivotal obesity trial, over 56 to 72 weeks.
Tirzepatide: the highest results recorded
Tirzepatide (Zepbound for weight, Mounjaro for diabetes) set the current ceiling for GLP-1 weight loss results. In SURMOUNT-1, the 72-week obesity trial, the 15 mg dose produced about 20.9% mean weight loss, the 10 mg dose about 19.5%, and the 5 mg dose about 15.0%. It is a dual agonist, hitting both the GIP and GLP-1 receptors, which is the leading explanation for the edge. The trial detail is in Zepbound clinical trial results, and the mechanism in how tirzepatide works.
Semaglutide: the benchmark
Semaglutide (Wegovy for weight, Ozempic for diabetes) was the drug that redefined what a weight medicine could do. In STEP-1, the 68-week trial, the 2.4 mg weekly dose produced about 14.9% mean weight loss, roughly double the older drugs of its day. At the lower diabetes doses sold as Ozempic, weight loss is smaller, which is why the brand you take and the dose matter as much as the molecule. See how semaglutide works for weight loss and the real-world picture in weight loss on semaglutide.
Liraglutide and the older results
Liraglutide (Saxenda) is the daily, first-generation GLP-1 for weight, and its SCALE trial showed about 8% mean weight loss over 56 weeks. That was impressive when it arrived, but the once-weekly drugs that followed roughly doubled it, which is why liraglutide is now the lowest line on the index. It remains a valid option, particularly where a daily dose or specific tolerability profile fits.
Why your results may differ from the trial average
Trial averages are a starting point, not a promise. Real-world GLP-1 weight loss results depend on reaching and tolerating the higher doses, staying on the drug long enough (the trials ran 12 to 18 months), and pairing it with adequate protein, activity, and muscle preservation. They also depend on continuation: stopping tends to reverse much of the loss, which we cover in weight regain after stopping. For setting an expectation that fits you, see realistic weight loss goals on GLP-1 and real patient outcomes in GLP-1 before and after results. What each route costs to get there is in our companion GLP-1 Cost Index.
How quickly GLP-1 results appear
The headline trial figures are end-points reached over a year or more, not what you see in the first month. GLP-1 medications are titrated upward slowly, starting at a low dose and stepping up every four weeks to limit nausea, so the early weeks are about tolerance rather than maximum effect. Most people see weight start to move within the first one to two months, with the steepest loss through the middle of the course as the dose climbs toward maintenance, and a gradual flattening as the body approaches a new set point. In the obesity trials, weight was still declining at the six-month mark and only leveled off later, which is why stopping early tends to leave results on the table. A plateau is normal and expected, not a sign the drug has stopped working; it usually marks the point where intake and energy needs have rebalanced at a lower weight.
GLP-1 results versus diet and older drugs
The numbers in this index look modest as percentages until you set them against what came before. Intensive lifestyle programs, the gold standard for decades, average roughly 3% to 5% sustained weight loss, and most diets give back much of the early loss within a year or two, a pattern rooted in the body's biological defense of its weight. The first generation of weight drugs landed in a similar single-digit range. Against that backdrop, semaglutide's ~14.9% and tirzepatide's ~20.9% are a step change, three to five times the durable loss of diet alone, which is why these medications reset expectations for the field. The gap also reframes the cost question: a more effective medicine that has to be continued is a different value proposition than a cheaper one that does less, which we lay out in the companion GLP-1 Cost Index. The honest caveat is that the comparison is not perfectly fair, since the GLP-1 trials also included lifestyle support, but even the medication's added effect over placebo-plus-lifestyle is large.
Scientific References
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Jastreboff AM, Aronne LJ, Ahmad NN, et al.
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)
New England Journal of Medicine · 387(3) · 2022PMID: 35658024
NEJM - 2
Wilding JPH, Batterham RL, Calanna S, et al.
Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP-1)
New England Journal of Medicine · 384(11) · 2021PMID: 33567185
NEJM - 3
Pi-Sunyer X, Astrup A, Fujioka K, et al.
A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management (SCALE)
New England Journal of Medicine · 373(1) · 2015PMID: 26132939
NEJM - 4
Drucker DJ
Mechanisms of Action and Therapeutic Application of Glucagon-like Peptide-1
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National Institute of Diabetes and Digestive and Kidney Diseases
Prescription Medications to Treat Overweight and Obesity
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NIH
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Frequently Asked Questions
Which GLP-1 has the best weight loss results?
In trial terms, tirzepatide (Zepbound) leads with up to about 20.9% mean weight loss over 72 weeks in SURMOUNT-1, ahead of semaglutide (Wegovy) at about 14.9% over 68 weeks in STEP-1, and liraglutide (Saxenda) at about 8% over 56 weeks in SCALE. Individual results vary, and the diabetes versions tend to show less weight loss than the dedicated obesity drugs.
How much weight can you lose on a GLP-1 on average?
It depends on the drug and dose. Pivotal trials reported roughly 8% with liraglutide, ~14.9% with semaglutide, and up to ~20.9% with tirzepatide, over 12 to 18 months. Real-world results vary with how high a dose you reach and tolerate, how long you stay on it, and whether you pair it with protein, activity, and muscle preservation.
How much more weight does tirzepatide take off than semaglutide?
In their respective top-dose obesity trials, tirzepatide reached about 20.9% mean weight loss versus semaglutide's ~14.9%, so roughly 6 percentage points more. Tirzepatide is a dual GIP/GLP-1 agonist, which is the leading explanation for the gap. The two have not been compared head-to-head for weight in a single published obesity trial at the time of writing, so cross-trial comparisons should be read with care.
Do GLP-1 weight loss results last after you stop?
Largely no. Trials of stopping GLP-1 medications show that much of the lost weight returns over the following year, because the drugs work while you take them. That makes GLP-1 treatment an ongoing therapy rather than a one-time course, and it is why maintenance planning and habit change matter alongside the medication.
Why is my weight loss less than the trial average?
Trial averages assume reaching and tolerating the top dose, staying on the drug for the full 12-to-18-month period, and trial-level support. Real-world results commonly fall below the headline figure when the dose is lower, the duration is shorter, or protein and activity are not optimized. Plateaus are also normal; the average is a midpoint, with many people above and below it.
Does compounded semaglutide or tirzepatide give the same results?
Compounded versions use the same active molecules, so results are generally expected to track the branded drugs at equivalent doses. The variables are dose accuracy and quality, which depend on the pharmacy, so a credentialed 503A or 503B facility with a real prescription matters. There are no large compounded-specific outcome trials, so the branded trial figures are the best available guide.
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Where to read next
Not medical advice. This guide is for general education only. GLP-1 medications, dosing, and treatment suitability are decisions for you and a licensed clinician who knows your full medical history.