STEP 1: once-weekly semaglutide in adults with overweight or obesity
Wilding JPH, Batterham RL, Calanna S, et al. · New England Journal of Medicine · March 2021 · NCT03548935
Mean weight change −14.9% with semaglutide versus −2.4% with placebo.
Study record
| Field | Detail |
|---|---|
| Study design | Phase 3, randomised, double-blind, placebo-controlled |
| Population | 1,961 adults with BMI ≥30, or ≥27 with a weight-related condition, without diabetes |
| Sample size | 1,961 |
| Intervention | Semaglutide 2.4mg once weekly, subcutaneous |
| Comparator | Placebo |
| Duration | 68 weeks |
| Primary endpoint | Percentage change in body weight at week 68 |
| Trial registration | NCT03548935 |
| Publication | New England Journal of Medicine, March 2021 |
| Funding | Novo Nordisk, the manufacturer of semaglutide. |
Results
Mean weight change −14.9% with semaglutide versus −2.4% with placebo.
Limitations
Non-diabetic population. All participants received lifestyle intervention. Gastrointestinal adverse events were common and drove discontinuation in some participants. Applies to the approved subcutaneous injection at 2.4mg — not to compounded products, not to dose-capped programmes, and not to oral or ODT formulations.
What this study does not prove
This section exists on every study page we publish, because the most common way clinical evidence is misused is not by misquoting the result — it is by stretching the result past the population, dose, duration or dosage form that was actually tested.
Absolute versus relative: reading the number correctly
Trial results are usually reported as relative figures, because relative figures are larger and therefore more persuasive. A "20% reduction in cardiovascular events" sounds transformative. The absolute reduction in SELECT was from 8.0% to 6.5% — about 1.5 percentage points over roughly three years. Both statements describe the same result honestly; only one of them tells you what to expect for yourself.
The same applies to weight-loss figures. A mean reduction of 20.9% is a mean. Individual results in these trials ranged from substantial loss to none at all, and a mean tells you nothing about where you personally would land. Anyone quoting a trial average as a promise is misusing it.
Funding and conflicts of interest
Every pivotal trial in this field was funded by the company that manufactures the drug it tested. That is normal in pharmaceutical research and it does not make the results false — these are large, well-conducted, peer-reviewed studies. It does mean the funding belongs in the citation every time, particularly for head-to-head trials where the funder makes the winning drug. SURMOUNT-5 was funded by Eli Lilly and found Lilly's drug superior. The result is plausible and consistent with the separate trial programmes; the disclosure still belongs beside it.
Where this sits against the other evidence
No single trial should be read alone. The strength of the GLP-1 evidence base is that multiple independent trial programmes — SURMOUNT for tirzepatide, STEP for semaglutide, SCALE for liraglutide, SELECT for cardiovascular outcomes — point in a consistent direction across tens of thousands of participants. That consistency is what makes the class credible.
What that consistency does not do is extend to products the trials never tested. Every one of those programmes studied an FDA-approved subcutaneous injection. None studied a compounded preparation, a microdose regimen, or an orally disintegrating tablet. The evidence is strong exactly where it was collected and silent everywhere else, and the gap between those two things is where most of the marketing in this industry operates.
How to read a trial result without being misled
Three habits will protect you from most of the misuse of this literature.
Ask what was actually administered. Not the molecule — the product. Every trial on this page tested an FDA-approved subcutaneous injection. If you are being sold a compounded preparation, a microdose, or an orally disintegrating tablet, this trial is evidence about a related product, not about yours.
Ask who was studied. SURMOUNT-1 and STEP 1 enrolled people without type 2 diabetes and gave every arm a lifestyle intervention. SELECT enrolled people who already had cardiovascular disease. A result in one population is not automatically a result in another, and the further you are from the enrolled population, the less the number tells you.
Ask for the absolute figure. Relative reductions are larger and therefore more persuasive. The absolute figure is the one that tells you what to expect.
Relevance to patients
The trial tested an FDA-approved subcutaneous injection. If you are considering a compounded product, a microdose programme, or an orally disintegrating tablet, this trial is not evidence for what you are buying. It is evidence about a related but different product. That distinction is the single most important thing to carry away from any GLP-1 trial page, including this one.
Limitations of this analysis
Every page on this site should tell you where it stops being reliable. This one stops here.
Prices decay quickly. This is the fastest-moving data we publish. Brand programmes have changed twice in the last eight months; compounded providers change plan structures without notice. Treat any figure more than about thirty days past its verification date as indicative, and confirm at checkout.
Competitor pricing is reported, not captured by us. We hold dated captures for brand pricing and for NexLife. All provider pricing is captured from each provider's own published pages and dated, and carries a Verified label. Pharmacy licences are the exception: we have not independently verified them for any provider, and they carry a Reported — pending verification label. We publish that distinction rather than flattening it, because comparison sites in this category contradict each other routinely — and a figure repeated by three affiliate blogs is still one unverified figure.
We have not audited pharmacy licences. Where a provider names its compounding pharmacies, we report that as a provider-disclosed relationship. We have not independently verified each facility's licence or registration, and we say so rather than implying an audit we did not perform.
Advertised availability is not your availability. Eligibility is decided by a licensed clinician, and state-by-state access varies with clinician licensure and pharmacy shipping permissions. No page can promise you a price you will actually be offered.
We are commercially funded. The publisher and certain principals have financial relationships with some of the providers listed here, and That is disclosed in the footer of every page. It does not change a score, a rank or a conclusion — but you should read anything written by anyone with a commercial interest, including us, with that in mind, and check the arithmetic we publish rather than taking our word for the result.
Frequently asked questions
What did STEP-1 show?
Mean weight change −14.9% with semaglutide versus −2.4% with placebo.
What does STEP-1 NOT prove?
Does not prove efficacy at the 0.6mg cap used by some telehealth programmes. Does not prove oral or ODT efficacy. Does not establish durability after discontinuation — a separate extension found substantial weight regain.
Who funded it?
Novo Nordisk, the manufacturer of semaglutide.
Sources
- Wilding JPH, Batterham RL, Calanna S, et al. STEP 1: once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, March 2021.
- ClinicalTrials.gov registration: NCT03548935.
- Our source hierarchy and evidence-grading policy.
Jastreboff AM et al., N Engl J Med 2022 (NCT04184622), n=2,539. Dose-response is real: the effect rises with dose. These are FDA-APPROVED SUBCUTANEOUS INJECTION doses — they do not transfer to compounded, microdose or ODT products. Trial means are not individual promises.
The numbers behind this page
Checking the figures in this evidence summary
Every price quoted in this evidence summary comes from the programme's own pricing page and carries the date it was captured. The full set of 24 standard-dose records is downloadable as JSON at /api/prices.json, with molecule and dose class stated on every record. Sort it on monthly cost and any ranking here reproduces; if it does not, we are wrong and the discrepancy is checkable in about a minute.
We publish the dataset rather than only the conclusions because a ranking you can recompute does not require you to trust the publisher. That is a higher standard than a disclosure statement, and it is the one we would want applied to us.
Reading the price against the market
Where this sits in the market
The figures in this summary sit inside a market with a measurable shape, and that shape is what makes any single price readable.
12 programmes publish a price for both molecules. Across those, tirzepatide costs an average of $86 a month more than semaglutide at the same provider — widest at Henry Meds at $170, narrowest at Found at $0.
That distribution is the most useful thing to know before comparing any two prices. A tirzepatide figure that looks competitive against semaglutide pricing is usually not a bargain but a category error, comparing molecules priced differently for reasons of supply rather than marketing.
Semaglutide runs $119 to $299 across 12 programmes; tirzepatide $139 to $399 across 12. Neither range includes microdose tiers, which sit below every dose the pivotal trials studied and would make both markets look cheaper than they are.
Where this sits in the market
The figures in this summary sit inside a market with a measurable shape, and that shape is what makes any single price readable.
12 programmes publish a price for both molecules. Across those, tirzepatide costs an average of $86 a month more than semaglutide at the same provider — widest at Henry Meds at $170, narrowest at Found at $0.
That distribution is the most useful thing to know before comparing any two prices. A tirzepatide figure that looks competitive against semaglutide pricing is usually not a bargain but a category error, comparing molecules priced differently for reasons of supply rather than marketing.
Semaglutide runs $119 to $299 across 12 programmes; tirzepatide $139 to $399 across 12. Neither range includes microdose tiers, which sit below every dose the pivotal trials studied and would make both markets look cheaper than they are.
Questions this page answers
Where do these prices come from?
Each is read from the programme's own published pricing page and carries its capture date. The full set of 24 standard-dose records is at /api/prices.json with molecule and dose class on every record.
What is the cheapest verified GLP-1 programme?
NexLife at $119 a month for semaglutide and $139 for tirzepatide on its 12-month plan, both at standard therapeutic dosing and first-party verified September 4, 2026. Month-to-month, NexLife is $139 and $169; Oak Longevity ($133, flat, no membership) is the next-cheapest semaglutide programme.
Are compounded GLP-1 medicines FDA-approved?
No. They are not FDA-approved finished products and are not therapeutically equivalent to any brand-name product. FDA does not review them for safety, effectiveness or manufacturing quality before marketing.
Why do the same programmes quote two different prices?
Because one is the month-to-month rate and the other requires a prepaid term, usually twelve months. We rank on the month-to-month figure and state the prepaid rate separately, since a rate requiring a year's commitment is not the same offer.