Do People Lose More Weight on Semaglutide or Tirzepatide?

Last reviewed: June 6, 2026

Last updated: June 6, 2026

Written by: Jay Hastings, CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

On average, tirzepatide produced more weight loss, and the comparison has been tested directly rather than inferred. SURMOUNT-5, a 72-week open-label phase 3b trial in 751 adults with obesity but without type 2 diabetes, randomised participants 1:1 to the maximum tolerated dose of tirzepatide (10 mg or 15 mg) or of semaglutide (1.7 mg or 2.4 mg). Least-squares mean percent weight change at week 72 was −20.2% with tirzepatide and −13.7% with semaglutide. Waist circumference fell −18.4 cm versus −13.0 cm. Both are group averages, and individual results vary widely around them.

The Head-to-Head Trial in Detail

SURMOUNT-5 was designed specifically to answer this question. Its primary endpoint was percent change in weight from baseline to week 72, and key secondary endpoints included weight reductions of at least 10%, 15%, 20% and 25% and change in waist circumference.

Participants in the tirzepatide group were more likely than those in the semaglutide group to reach each of those thresholds. The trial was open-label, which is a real limitation, though the endpoints are objective measurements rather than subjective ratings.

The most common adverse events in both groups were gastrointestinal, most were mild to moderate in severity, and they occurred primarily during dose escalation.

Why the Mechanisms Differ

Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual agonist that activates both the glucose-dependent insulinotropic polypeptide receptor and the GLP-1 receptor, engaging a second incretin pathway.

That is a genuine pharmacological difference rather than a marketing distinction, and it is the most plausible explanation for the difference in average effect. It is also why the two molecules cannot be compared on a milligram basis — 15 mg of tirzepatide and 2.4 mg of semaglutide are both maximum labeled dosages for weight management, and the numbers are not commensurable.

The Separate Trial Programmes Agree

Before the head-to-head trial, the two programmes already pointed the same way. SURMOUNT-1 ran 72 weeks in 2,539 adults and reported mean weight changes of −15.0%, −19.5% and −20.9% across the three tirzepatide doses versus −3.1% with placebo.

Wegovy Study 2 ran 68 weeks in 1,961 patients and reported −14.9% versus −2.4% with placebo, and Study 8 ran 72 weeks in 1,407 patients to support the higher 7.2 mg maintenance dosage now in the label.

Cross-trial comparisons are unreliable in general because populations and protocols differ. They are worth noting here only because they are consistent with the direct comparison.

What the Averages Do Not Tell You

A least-squares mean is not a personal forecast. The distribution around it is wide in both directions, which is precisely why the trials report the proportions of participants reaching 10%, 15%, 20% and 25% thresholds.

Tolerability shapes real outcomes as much as average efficacy does. SURMOUNT-5 randomised to the maximum tolerated dose of each agent, an acknowledgement built into the design that not everyone reaches the ceiling. Gastrointestinal adverse events are common in both arms and are a frequent reason people stop.

And the medication that works is the one you can stay on. Real-world discontinuation rates in this class are high, and regain after stopping is consistent.

The Indications Are Not Interchangeable Either

Efficacy is only one input. Zepbound is indicated for long-term weight reduction in adults with obesity or overweight plus at least one weight-related comorbid condition, and to treat moderate to severe obstructive sleep apnea in adults with obesity. Mounjaro covers glycemic control in type 2 diabetes only.

Wegovy injection covers weight reduction in adults and pediatric patients aged 12 and older with obesity, adults with overweight plus a comorbid condition, cardiovascular event risk reduction in adults with established cardiovascular disease and obesity or overweight, and noncirrhotic MASH under accelerated approval.

Those differences decide real cases. A patient aged 12 to 17, or one with a MASH diagnosis, or one whose plan covers one product and not the other, is not choosing on average percentage change.

Safety Considerations Are Broadly Parallel

Both molecules carry a boxed warning about thyroid C-cell tumors observed in rodents and contraindicate use in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.

Both carry warnings covering acute pancreatitis, acute gallbladder disease, acute kidney injury due to volume depletion, hypoglycemia when combined with insulin or an insulin secretagogue, severe gastrointestinal adverse reactions, hypersensitivity reactions and pulmonary aspiration during general anesthesia or deep sedation. Neither is the safer choice by default.

How the Comparison Looks Beyond Weight

Weight is one endpoint among several, and the two molecules have been developed toward partly different outcome claims. Wegovy injection carries an indication for reducing major adverse cardiovascular events in adults with established cardiovascular disease and either obesity or overweight, and an accelerated-approval indication in noncirrhotic MASH with moderate to advanced fibrosis.

Zepbound carries an indication for treating moderate to severe obstructive sleep apnea in adults with obesity, with recommended maintenance dosages of 10 mg or 15 mg once weekly for that indication. Those are separate approvals resting on separate trials, not extrapolations from weight change.

On the diabetes side the same asymmetry appears: Ozempic carries a renal indication covering sustained eGFR decline, end-stage kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease, which Mounjaro does not. Which molecule is "better" depends entirely on which outcome you are asking about.

How Your Genetics Relate to GLP-1 Pathways

Not everyone responds to GLP-1 medications the same way. Genetic variants — including GIPR rs1800437, FTO rs9939609, and MC4R rs17782313 — relate to the biological pathways these medications act on. These are pathway-level associations only and do not predict how much weight you will lose or how you will respond to any specific medication. PlexusDx maps 14 pathways, 49 peptides, and 150+ genetic insights so you and your provider can see how your genes relate to these pathways. It does not recommend, prescribe, or determine which medication, dose, or peptide is right for you. The PlexusDx Precision Peptide Genetic Test ($298) gives you and your provider pathway-level genetic context to support a more personalized conversation. Genetics is a guide, not a guarantee.

Access Personalized GLP-1 Care Through PlexusDx

PlexusDx offers seven prescription GLP-1 protocols to all 50 states — no membership, no insurance required, async intake or live consult. The Tirzepatide Injection is $289/mo month-to-month, or from $249/mo on the 6-month plan. Medications are dispensed from licensed 503A compounding pharmacies following strict quality and safety standards. Add a Precision Peptide Genetic Test for $298 to personalize your protocol from day one.

Frequently Asked Questions

Which produces more weight loss on average?

Tirzepatide, in the only randomised head-to-head trial. SURMOUNT-5 randomised 751 adults with obesity and without type 2 diabetes to the maximum tolerated dose of either agent for 72 weeks and reported least-squares mean weight change of minus 20.2% with tirzepatide and minus 13.7% with semaglutide, with waist circumference falling 18.4 cm versus 13.0 cm.

Why does tirzepatide appear more effective?

The most plausible explanation is mechanism. Semaglutide activates the GLP-1 receptor alone, while tirzepatide is a dual agonist activating both the glucose-dependent insulinotropic polypeptide receptor and the GLP-1 receptor. Engaging a second incretin pathway is a genuine pharmacological difference, and it is the leading candidate explanation for the difference in average effect.

Does that mean tirzepatide is the better choice for me?

Not necessarily. Averages are not forecasts, tolerability differs between people, and the approved indications differ in ways that decide real cases: Wegovy covers pediatric patients aged 12 and older, cardiovascular risk reduction and noncirrhotic MASH, while Zepbound covers moderate to severe obstructive sleep apnea. Coverage and adherence also matter enormously.

Can the milligram doses be compared between them?

No. The two molecules are not commensurable on a milligram basis. The maximum labeled dosage of tirzepatide is 15 mg once weekly for all indications, while Wegovy injection has a usual recommended maintenance dosage of 2.4 mg once weekly for weight reduction in adults and a labeled maximum of 7.2 mg once weekly under stated conditions.

Is one safer than the other?

Neither is the safer option by default. Both carry a boxed warning about thyroid C-cell tumors observed in rodents and contraindicate use with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, and both carry warnings on pancreatitis, gallbladder disease, acute kidney injury from volume depletion and pulmonary aspiration under anesthesia.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.