Featured image: A clinical-research illustration representing two-year weight retention with tirzepatide and semaglutide. Original visual created for GLP-1 Reviews.
Last Updated: August 21, 2026
Article type: Clinical Evidence / Comparison
Primary keyword: tirzepatide vs semaglutide
Suggested slug: tirzepatide-vs-semaglutide-2-year-real-world-weight-retention-regain-2026
Meta description: New 2026 data compares tirzepatide vs semaglutide on two-year weight retention, regain, trial efficacy, dosing, and long-term treatment planning.
The latest real-world evidence adds an important dimension to the tirzepatide vs semaglutide discussion: what happens after the first year of weight loss when patients continue treatment?
In a large Epic Research Cosmos cohort of 25,213 U.S. adults without diabetes, most people who had lost at least 5 pounds during year one and stayed on treatment carried most of that result into a second year. At month 24, 53.1% of semaglutide users and 52.9% of tirzepatide users remained within a narrow band of their year-one weight. Substantial regain: defined as regaining at least 25% of the weight lost during year one: was reported in 14.9% of semaglutide users and roughly 8% of tirzepatide users.Epic Research, Aug. 13, 2026
The result is not a simple declaration that one medicine is universally better. It shows that both treatments can support continued weight control among people who remain on therapy, while the real-world pattern of regain is gradual and partial for most continuing users.
The two medicines at issue are tirzepatide (Mounjaro, Zepbound) and semaglutide (Ozempic, Wegovy). SURMOUNT-5 provides the controlled head-to-head efficacy context: after 72 weeks, tirzepatide produced a mean weight reduction of 20.2%, compared with 13.7% for semaglutide. The Epic findings extend the question from initial loss to longer-term retention.
Key findings from the new two-year data
- 25,213 adults without diabetes were studied after remaining on a GLP-1 medication for at least one year and losing at least 5 pounds during that first year.Epic Research
- At 24 months, 53.1% of semaglutide users and 52.9% of tirzepatide users remained within a narrow band of their year-one weight.
- An additional 31.9% of semaglutide users and 39.3% of tirzepatide users continued losing weight beyond their year-one measurement.
- Regaining at least 25% of year-one weight loss occurred in 14.9% of semaglutide users and approximately 8% of tirzepatide users.
- Returning fully to baseline weight was uncommon: 1.5% for semaglutide and no more than 1% for tirzepatide in the study’s continuing-user population.
- In SURMOUNT-5, tirzepatide reduced body weight by 20.2% at 72 weeks, compared with 13.7% for semaglutide, a difference of 6.5 percentage points.NEJM/PubMed
- The Epic study followed patients only while they remained on treatment. It therefore describes retention among continuing users, not the expected result after stopping medication.
Headline statistic
At 24 months, substantial regain affected 14.9% of continuing semaglutide users versus approximately 8% of continuing tirzepatide users: but more than half of both groups remained near their year-one weight.
Source: Epic Research Cosmos cohort, published August 13, 2026.
Two-year Epic retention data: what the percentages measure
The Epic Research analysis is useful because it measures a question that randomized trials often do not answer directly: how weight changes during a second year of treatment in routine practice.
The study included adults who met several conditions:
- They were at least 18 years old.
- They did not have diabetes.
- They were starting a GLP-1 medication for the first time in the study framework.
- They stayed on the same active ingredient without a prescription gap of more than 60 days.
- They had weight measurements near treatment initiation and near the one-year mark.
- They lost at least 5 pounds during the first year.
The researchers then tracked weight at monthly checkpoints from months 13 through 24. The analysis grouped patients according to whether they maintained their year-one weight, lost additional weight, regained at least 25% of their year-one loss, or returned to baseline.
This definition matters. “Maintained weight loss” did not mean that every patient preserved every pound lost. It meant that the patient’s weight stayed within a narrow band of the year-one measurement. Similarly, “substantial regain” did not mean a full return to starting weight. It meant that at least one-quarter of the year-one loss had been regained.
That makes the data more clinically realistic. Weight naturally fluctuates with hydration, illness, menstrual cycles, travel, dietary changes, activity, and measurement conditions. A patient can regain several pounds without losing the entire benefit of treatment.
Epic Research 24-month outcomes
| Outcome at month 24 | Semaglutide | Tirzepatide |
|---|---|---|
| Maintained weight within a narrow band of year-one weight | 53.1% | 52.9% |
| Lost additional weight after year one | 31.9% | 39.3% |
| Regained at least 25% of year-one weight loss | 14.9% | Approximately 8% |
| Returned fully to baseline weight | 1.5% | No more than 1% |
Source: Epic Research, Cosmos EHR cohort, published August 13, 2026. The study followed patients only while they remained on medication.
The headline comparison is close in the maintenance category: 53.1% versus 52.9%. The larger difference appears in the distribution of other outcomes. A greater share of tirzepatide users continued losing weight after the first year, while the proportion experiencing substantial regain was lower.
However, these figures should not be interpreted as a randomized comparison. The groups may have differed in treatment dose, access, adherence, baseline weight, duration of therapy, prescribing patterns, and other factors that EHR data cannot fully control.
What SURMOUNT-5 adds to the retention story
Epic Research shows what happens among continuing users in routine care. SURMOUNT-5 shows the average weight-loss difference under a more controlled head-to-head design.
SURMOUNT-5 was a phase 3b, randomized, open-label trial involving 751 adults with obesity or overweight and weight-related health conditions who did not have type 2 diabetes. Participants received either tirzepatide or semaglutide once weekly for 72 weeks, with doses increased during a structured escalation period.
The trial compared maximum tolerated doses:
- Tirzepatide: 10 mg or 15 mg weekly.
- Semaglutide: 1.7 mg or 2.4 mg weekly.
At week 72:
- Tirzepatide produced a least-squares mean weight change of −20.2%.
- Semaglutide produced a least-squares mean weight change of −13.7%.
- The between-group difference was 6.5 percentage points.
- Waist circumference declined by 18.4 cm with tirzepatide and 13.0 cm with semaglutide.
- Tirzepatide was superior on the prespecified weight-loss thresholds of at least 10%, 15%, 20%, and 25%, as well as waist circumference.
The full study record is available through ClinicalTrials.gov’s SURMOUNT-5 record, and the primary results are summarized in the New England Journal of Medicine publication indexed by PubMed.
Trial efficacy and real-world retention are different questions
| Evidence source | Participants | Main question | Key result |
|---|---|---|---|
| SURMOUNT-5 | 751 | Which treatment produced more average weight loss over 72 weeks? | Tirzepatide −20.2% vs semaglutide −13.7% |
| Epic Research Cosmos | 25,213 overall cohort | What happened during a second year among people who stayed on treatment? | 53.1% semaglutide and 52.9% tirzepatide remained near year-one weight |
| Epic Research Cosmos | Continuing users | How common was substantial regain? | 14.9% semaglutide vs approximately 8% tirzepatide |
Sources: NEJM/SURMOUNT-5 and Epic Research. The studies used different designs and should not be treated as interchangeable.
The distinction is important for patients. A medicine can produce greater average weight loss during the first 12 to 18 months, while individual maintenance outcomes still vary considerably. The Epic study suggests that both medicines can support continued control into a second year for patients who remain on therapy, but it does not establish that tirzepatide prevents regain for every patient.
Why continuation matters
The strongest practical message from the Epic data is that retention was observed among people who continued taking the medication.
Patients were censored from the analysis after a gap of more than 60 days between prescriptions or dispenses. That means the 24-month results do not describe everyone who started treatment. They describe patients who remained engaged with therapy long enough to be measured at later checkpoints.
This creates an important limitation but also reflects how long-term treatment works in practice. If medication is helping control appetite and food intake, stopping it may remove part of that support. If side effects, cost, supply problems, or coverage interruptions cause a treatment gap, the patient’s weight trajectory may change.
The Epic researchers specifically noted that later checkpoints are enriched for people who tolerated and responded to treatment. In research terms, this creates a form of survivor bias. In practical terms, it means the study cannot tell a first-time patient exactly what will happen after two years.
It does show that continued treatment can be associated with:
- Stable weight after the initial loss.
- Additional weight reduction beyond year one.
- Gradual, partial regain for a minority of continuing users.
- Rare full return to baseline among the patients still being followed.
What gradual regain means for patients
Regain is not automatically treatment failure.
A patient who regains 5 or 10 pounds after losing 50 pounds may still have achieved a substantial health benefit. The more clinically relevant questions are:
- How much weight was regained?
- Over what period?
- Was medication taken consistently?
- Was the patient still at a maintenance dose?
- Did side effects limit treatment?
- Did medication access or cost cause an interruption?
- Were sleep, stress, activity, nutrition, or another medical condition changing?
The Epic data shows gradual regain beginning after the one-year mark, but it does not identify the cause for each patient. EHR records generally do not capture all dietary changes, exercise patterns, sleep disruption, menopause-related changes, emotional stress, or medication adherence.
A modest fluctuation should be discussed during routine follow-up rather than treated as an emergency. A rapid or persistent change deserves a clinical review, particularly if it occurs alongside worsening appetite, medication interruptions, new symptoms, or changes in another condition.
Dosing and maintenance decisions should be clinical
Neither the Epic study nor SURMOUNT-5 supports self-directed dose changes.
Both tirzepatide and semaglutide are typically introduced at lower doses and increased gradually according to the prescribing information and the patient’s response. In SURMOUNT-5, dose escalation occurred at regular intervals, but participants could remain at a maximum tolerated dose rather than automatically reaching the highest dose.
Patients should not:
- Increase a dose faster than instructed.
- Take extra medication to compensate for weight changes.
- Restart at a previous dose after a prolonged interruption without asking a clinician.
- Switch between semaglutide and tirzepatide without a prescriber’s plan.
- Treat a short-term plateau as a reason to escalate immediately.
- Continue a dose that causes persistent or severe symptoms without contacting the prescribing team.
A maintenance plan may involve holding a dose, delaying an increase, adjusting the treatment schedule, addressing side effects, or evaluating another cause of weight change. The appropriate decision depends on the medicine, dose, medical history, response, and access to follow-up care.
For buyers comparing telehealth programs, the quality of ongoing support matters as much as the initial prescription. The Mochi Health review and Ro review provide examples of how GLP-1 Reviews evaluates clinical access, support, medication sourcing, and patient protections at the provider level. Those provider assessments are separate from the clinical evidence comparing the two medicines.
Side effects: frequency, duration, and severity
The most common adverse effects in SURMOUNT-5 were gastrointestinal. The NEJM abstract states that these events were generally mild to moderate and occurred primarily during dose escalation.NEJM SURMOUNT-5 results
Common symptoms associated with this medication class include:
- Nausea.
- Vomiting.
- Diarrhea.
- Constipation.
- Abdominal discomfort.
- Reduced appetite.
These symptoms often become more noticeable after starting treatment or increasing the dose, then improve as the body adjusts. That pattern is not guaranteed, and a symptom that persists, worsens, or interferes with hydration and daily activities should be reviewed with a clinician.
The official Wegovy prescribing information and Zepbound prescribing information include warnings involving severe gastrointestinal reactions, pancreatitis, and gallbladder disease.
When to contact a clinician promptly
Contact the prescribing clinician if nausea, diarrhea, constipation, or vomiting is persistent, worsening, or making it difficult to eat and drink normally. Dehydration can become clinically significant, especially when vomiting or diarrhea continues.
Seek urgent medical evaluation for:
- Severe or persistent abdominal pain, especially if it radiates to the back.
- Repeated vomiting or inability to keep fluids down.
- Severe abdominal swelling or symptoms suggesting an obstruction.
- Upper-right abdominal pain with fever.
- Yellowing of the skin or eyes.
- Dark urine or unusually pale stools.
- Signs of an allergic reaction, such as swelling of the face or throat or trouble breathing.
These symptoms do not prove that a medication caused a serious complication, but they warrant prompt evaluation. The prescribing information directs patients and clinicians to evaluate suspected pancreatitis and gallbladder disease rather than attempting to manage severe symptoms independently.
Do not compare side-effect percentages casually
Side-effect percentages from different trials are not automatically comparable. The dose, duration, population, treatment design, reporting method, and study conditions may differ.
SURMOUNT-5 is more useful for a direct comparison because both medicines were studied in the same trial population. Even then, individual tolerability varies. Some patients may tolerate semaglutide better; others may tolerate tirzepatide better. A higher average weight-loss result does not guarantee a better personal result if side effects prevent consistent treatment.
What the Epic data does: and does not: say about stopping
The Epic study does not measure weight outcomes after discontinuation. Patients were followed only while they remained on the medication.
That limitation prevents a common misreading: the study should not be used to claim that most people will maintain their weight after stopping tirzepatide or semaglutide. It also should not be used to claim that a small amount of regain during continued treatment means the patient can stop without a plan.
A discontinuation decision should account for:
- The reason treatment is being stopped.
- Whether the patient has reached a stable maintenance phase.
- Current weight and metabolic health.
- Appetite and hunger changes.
- Insurance or cash-pay access.
- Whether another treatment will replace the medication.
- The clinician’s plan for monitoring weight and related health markers.
Patients considering a switch or discontinuation should ask their prescriber how to transition safely and how often follow-up should occur. Medication should not be stopped, restarted, or combined with another GLP-1 product without medical direction.
Best for specific patient scenarios
Best for patients prioritizing greater average weight loss in a head-to-head trial: tirzepatide
In SURMOUNT-5, tirzepatide produced a larger average reduction in body weight than semaglutide at 72 weeks: 20.2% versus 13.7%. This scenario applies to patients whose primary treatment discussion centers on average weight-loss efficacy and who are clinically appropriate for tirzepatide.
The result is a population average, not a guarantee. Tolerability, access, dose response, and adherence still matter.
Best for patients focused on maintaining a year-one result while continuing treatment: both require individualized review
The Epic study found nearly identical proportions of semaglutide and tirzepatide users: 53.1% and 52.9%: within the defined maintenance band at 24 months.
That result does not create a clear maintenance winner. It supports a more practical conclusion: long-term maintenance depends on continued treatment, tolerability, consistent access, and follow-up rather than on a single headline percentage.
Best for patients who want to understand continued-loss potential after year one: tirzepatide showed a larger continuing-loss share
At month 24, 39.3% of continuing tirzepatide users had lost additional weight beyond the year-one measurement, compared with 31.9% of continuing semaglutide users.
This is an observational finding, so it should be treated as a signal rather than a guaranteed drug effect. It may be relevant when discussing whether a patient’s weight trend has plateaued, continued downward, or begun to rise.
Best for patients who need a maintenance plan after a plateau: whichever medicine can be used consistently and monitored appropriately
A plateau is not automatically a reason to switch. A clinician may first review the current dose, duration, adherence, side effects, diet, physical activity, sleep, other medications, and medical conditions.
The more practical choice is often the treatment that a patient can access, tolerate, and continue under appropriate medical supervision.
Best for patients comparing telehealth programs: evaluate ongoing support, not just medication price
The medication comparison does not determine which telehealth provider is the right fit. Buyers should compare:
- Whether the provider offers live clinician access.
- How dose adjustments are handled.
- Whether labs are included or billed separately.
- Which medication formulations are available.
- How pharmacy fulfillment works.
- Whether support continues after the first prescription.
- What cancellation and refund terms apply.
GLP-1 Reviews publishes its provider scoring system at the official review methodology page. That methodology evaluates authenticity, clinical quality, trust, reputation, access, support, value, and consumer protection. It should not be confused with the clinical efficacy results from SURMOUNT-5 or the retention percentages from Epic Research.
Cost and access remain part of long-term retention
A patient cannot maintain treatment with a medicine that is unavailable or unaffordable.
For self-pay consumers, the total monthly cost may include:
- The medication.
- A telehealth membership.
- Consultation fees.
- Laboratory testing.
- Shipping.
- Follow-up visits.
- Supplies required for administration.
- Costs associated with a dose change.
Our Ozempic vs. Wegovy vs. Zepbound cost comparison explains why brand-name list prices, manufacturer self-pay programs, insurance coverage, and compounded pathways can produce very different totals.
Cost should be evaluated over six or twelve months rather than only during an introductory offer. A lower first-month price does not necessarily make a program more affordable if the recurring fee, medication cost, or cancellation terms are unclear.
Access interruptions can also affect weight trajectories. Before starting, ask what happens if:
- A pharmacy cannot fill the prescription.
- Insurance coverage changes.
- A prior authorization expires.
- The provider changes its medication options.
- The patient needs a lower dose because of side effects.
- A shipment is delayed.
- The patient wants to transfer care to another clinician.
Limitations of the current evidence
The new Epic data is valuable, but it has several limitations:
- It is observational. Patients were not randomly assigned to semaglutide or tirzepatide.
- It included continuing users. People who stopped treatment were no longer followed in the two-year analysis.
- The study excluded direct switchers during the first year. The results do not describe every real-world treatment pathway.
- Dose information changes the interpretation. Different doses can produce different weight trajectories, but the study does not provide a randomized dose comparison.
- Lifestyle factors were not fully captured. EHR data cannot reliably measure every change in diet, activity, sleep, stress, or adherence.
- Weight measurements vary. Measurements may occur in different clinical settings using different equipment.
- The cohort required at least 5 pounds of first-year loss. The findings do not describe people who started treatment but did not lose at least that amount.
- The population did not have diabetes. The results should not automatically be generalized to patients with type 2 diabetes.
SURMOUNT-5 has a different limitation: it was a controlled, open-label trial lasting 72 weeks, not a two-year real-world retention study. Its results answer the question of comparative weight-loss efficacy under trial conditions, while Epic answers a longer-term question among selected continuing users.
Conclusion: the retention conversation is more nuanced than a winner-takes-all comparison
The latest evidence changes the way patients should think about tirzepatide vs semaglutide.
SURMOUNT-5 showed greater average weight loss with tirzepatide at 72 weeks: 20.2% versus 13.7%. Epic Research then showed that among continuing users without diabetes, both medicines were associated with substantial weight retention into a second year. At 24 months, 53.1% of semaglutide users and 52.9% of tirzepatide users remained near their year-one weight.
Tirzepatide had a lower observed rate of substantial regain: approximately 8% versus 14.9% for semaglutide: and a larger share of users continued losing weight after year one. But the Epic study was not randomized, followed only continuing users, and cannot prove that tirzepatide prevents regain for every patient.
The most defensible patient-level conclusions are:
- Best for greater average weight loss in the SURMOUNT-5 population: tirzepatide.
- Best for two-year maintenance among continuing users: both showed meaningful retention, with nearly identical maintenance-band percentages.
- Best for minimizing the chance of substantial regain in this observational cohort: tirzepatide showed a lower observed rate, but the result requires cautious interpretation.
- Best for long-term treatment planning: the medicine that a patient can access, tolerate, continue, and monitor with a qualified clinician.
Weight retention is not determined by the drug name alone. It also depends on treatment continuity, dose tolerance, side-effect management, affordability, pharmacy reliability, nutrition, activity, sleep, and follow-up care.
This article is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting any medication.
FAQ: Tirzepatide vs Semaglutide and Two-Year Weight Regain
Does tirzepatide cause less weight regain than semaglutide after two years?
In the Epic Research cohort of continuing users without diabetes, approximately 8% of tirzepatide users regained at least 25% of their first-year weight loss by month 24, compared with 14.9% of semaglutide users. The study was observational and followed patients only while they remained on treatment, so it does not prove that tirzepatide prevents regain in every patient.
How much weight did tirzepatide and semaglutide reduce in SURMOUNT-5?
In the 751-person SURMOUNT-5 trial, tirzepatide reduced body weight by 20.2% at 72 weeks, while semaglutide reduced body weight by 13.7%. Tirzepatide was also superior on waist circumference and the prespecified thresholds of at least 10%, 15%, 20%, and 25% weight loss. The trial included adults with obesity or overweight without type 2 diabetes.
Does the Epic study show what happens after stopping semaglutide or tirzepatide?
No. Epic Research followed patients only while they continued taking the medication, and patients were censored after a prescription gap of more than 60 days. The study therefore describes second-year weight trends among continuing users, not weight regain after discontinuation. Patients considering stopping should discuss a transition and monitoring plan with their prescriber.
Is regaining some weight during the second year a treatment failure?
No. Partial regain does not necessarily mean treatment failure, especially if a patient retains a substantial portion of the original loss. Weight can fluctuate for many reasons, including medication interruptions, dose changes, sleep, stress, activity, diet, and other medical conditions. Persistent or rapid regain should prompt a clinical review rather than an unsupervised dose change.
Which medication is better for long-term weight maintenance?
The available evidence does not support one universal answer for every patient. Tirzepatide produced greater average weight loss in SURMOUNT-5 and had a lower observed rate of substantial regain in the Epic continuing-user cohort. However, semaglutide and tirzepatide both showed meaningful two-year retention. The most appropriate option depends on clinical eligibility, tolerability, access, cost, and the patient’s ability to continue treatment under medical supervision.
What should patients do if they develop severe abdominal pain while taking either medicine?
Patients should contact a healthcare provider promptly or seek urgent medical evaluation for severe or persistent abdominal pain, particularly if it radiates to the back or occurs with vomiting. The official prescribing information for Wegovy and Zepbound warns about pancreatitis and gallbladder disease. Do not attempt to diagnose or manage severe symptoms by changing the dose yourself.
Primary sources and data notes
- Epic Research: Most adults without diabetes maintain their GLP-1 weight loss through a second year ; published August 13, 2026.
- NEJM SURMOUNT-5 trial publication via PubMed : 751 participants, 72-week head-to-head results.
- ClinicalTrials.gov: SURMOUNT-5, NCT05822830 : study design, eligibility, dosing framework, and enrollment.
- Wegovy prescribing information : official safety and prescribing information.
- Zepbound U.S. prescribing information : official safety and prescribing information.
Corrected 9 October 2026. We removed 2 generated images from this article. Generated images on this site no longer show certifications, organisations, products, prices or figures unless the specific claim has been checked.
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