GLP-1 Receptor Agonist

The story

1. 1983 Bell et al. sequence preproglucagon and reveal two previously unknown glucagon-like peptides
2. 1986 Mojsov and Habener show GLP-1(7-37) is the bioactive processed form
3. 1987 Three groups (Holst; Kreymann/Bloom; Drucker/Habener) independently show GLP-1 is insulinotropic
4. 1992 John Eng isolates exendin-4 from Gila monster venom — a DPP-4-resistant natural analogue
5. 1993 Nauck shows GLP-1, unlike GIP, retains insulinotropic action in type 2 diabetes
6. 2005-04-28 Exenatide (Byetta) approved — first GLP-1 receptor agonist
7. 2014-12-23 Liraglutide (Saxenda, the 3.0 mg presentation — a comparator's labelled strength) approved for chronic weight management — the class's first obesity indication
8. 2016 SUSTAIN-6 reports a 26% relative reduction in MACE with semaglutide in type 2 diabetes
9. 2017-12-05 Semaglutide (Ozempic) approved for type 2 diabetes
10. 2021-02 / 2021-06-04 STEP 1 published (−14.9% at 68 weeks); Wegovy approved for chronic weight management
11. 2022-05-13 / 2022-07 Tirzepatide (Mounjaro) approved for type 2 diabetes; SURMOUNT-1 published (−20.9% at 72 weeks)
12. 2023-11-08 / 2023-11 Tirzepatide (Zepbound) approved for obesity; SELECT published — 20% MACE reduction in obesity without diabetes
13. 2024-03-08 FDA adds a cardiovascular risk-reduction indication to Wegovy — the first for an obesity drug
14. 2024-10-02 / 2025-02-21 FDA declares the tirzepatide and then the semaglutide shortages resolved, starting the clock on compounding cutoffs
15. 2024-12-20 Zepbound approved for moderate-to-severe obstructive sleep apnoea with obesity — first drug for OSA
16. 2025-05 / 2025-07 SURMOUNT-5 published: tirzepatide −20.2% vs semaglutide −13.7% at 72 weeks, head to head
17. 2025-09-18 OASIS 4 published — the trial behind the oral approval. Once-daily oral semaglutide produced an estimated mean weight change of −13.6% to week 64 vs −2.2% on placebo (difference −11.4 percentage points, 95% CI −13.9 to −9.0), n=307
18. 2025-12-22 Wegovy tablets approved under NDA 218316 — first oral GLP-1 for weight management. Original submission ORIG 1, submission class Type 3 — New Dosage Form; approved tablet strengths 1.5 / 4 / 9 / 25 mg, sponsor Novo Nordisk. Those strengths name the approved presentation, a regulatory product record rather than an exposure. ⚠️ This is a different application from the oral semaglutide tablets under NDA 213051 (RYBELSUS, and the OZEMPIC-branded oral tablets at 1.5 / 4 / 9 mg), which are indicated for type 2 diabetes only and carry no weight-management indication. The trial behind this approval is published and is the row above
19. 2026-02-24 Novo Nordisk announces a US list-price cut to $675/month for Wegovy, Ozempic and Rybelsus, stated as effective 2027-01-01. ⚠️ Per sponsor announcement — a company statement of pricing intent, not a completed event

What it does

• body weight
• HbA1c
• ApoB
• blood pressure

What the evidence shows

Semaglutide cut major adverse cardiovascular events by a fifth in people who were overweight or obese and had heart disease but no diabetes — the first demonstration anywhere that treating obesity pharmacologically prevents heart attacks and strokes (SELECT, n=17,604; HR 0.80, 95% CI 0.72–0.90) — and randomized head-to-head trials inside the class have settled the weight question rather than leaving it to cross-trial arithmetic, with tirzepatide beating semaglutide in obesity (SURMOUNT-5, −20.2% vs −13.7%) and in type 2 diabetes (SURPASS-2). Behind those sit double-digit phase 3 programmes for both molecules, further cardiovascular outcome trials measuring hard events rather than surrogates (SUSTAIN-6, n=3,297; SURPASS-CVOT, n=13,299), hard-endpoint trials in chronic kidney disease, heart failure with preserved ejection fraction, obstructive sleep apnoea and steatohepatitis, and approved US and EU labelling for the indications this file discusses. The single biggest limitation is structural rather than methodological — no efficacy row in this file comes from a trial that neither manufacturer paid for. Every randomized figure here was produced by Novo Nordisk or Eli Lilly, with company employees among the authors, so a company's registry posting, its press release and its published paper about one trial are one entity and one source, not three; the independent material in the file is mostly about harms rather than effects. The thinnest parts of an otherwise thick record are long-term body composition, durability beyond about four years, and the transfer from pivotal trials that ran 40–72 weeks with supervised titration, structured lifestyle support and BMI entry criteria to real-world use that is indefinite, unsupervised, often outside those BMI criteria and, for a still-material fraction, supplied as compounded or gray-market material of unverified strength.

Overall evidence strength: High certainty

• STEP 1 — Wilding et al. (2021) — semaglutide at its weight-management maintenance dose in obesity without diabetes (2021) Randomized controlled trial

  People taking weekly semaglutide lost about 15% of their body weight over sixteen months, against about 2% on placebo, and half of them lost 15% or more — an effect several times larger than any previously approved weight-loss drug. What it does not show is what happens after the trial ends, whether the loss is durable, or what the weight is made of; the trial ran 68 weeks, everyone received lifestyle counselling, and body composition was measured only in a small sub-study.

  Source PMID 33567185

• SELECT — Lincoff et al. (2023) — cardiovascular outcomes in obesity **without** diabetes (2023) Randomized controlled trial

  This is the most consequential trial in the class, because it is the one that measured deaths and heart attacks rather than kilograms. Over roughly three and a half years, semaglutide reduced the combined rate of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke by about a fifth in people who were overweight or obese and had heart disease but not diabetes — the first demonstration that treating obesity pharmacologically prevents cardiovascular events. It does not show that the benefit comes from the weight loss itself (the trial cannot separate weight loss from direct drug effects), and it enrolled only people with established cardiovascular disease, so it says nothing about primary prevention in healthy people.

  Source PMID 37952131

• SUSTAIN-6 — Marso et al. (2016) — the cardiovascular safety trial that found benefit (2016) Randomized controlled trial

  A trial designed only to rule out harm found benefit instead — a 26% lower rate of cardiovascular death, heart attack or stroke — and simultaneously produced the class's most awkward safety signal, a near-doubling of diabetic retinopathy complications, which the investigators attributed to the speed of glucose lowering rather than to the drug. Because it was powered for non-inferiority, the efficacy result is formally exploratory.

  Source PMID 27633186

• SURPASS-2 — Frías et al. (2021) — tirzepatide vs semaglutide in type 2 diabetes (2021) Case series (uncontrolled)

  The first head-to-head inside the class, and tirzepatide won on both glucose and weight — but the comparator was semaglutide at its diabetes maintenance dose, not the higher weight-management dose, so this trial does not settle which drug produces more weight loss in obesity. The trial was also open-label, which matters for subjective and behaviour-mediated endpoints.

  Source PMID 34170647

• SURMOUNT-1 — Jastreboff et al. (2022) — tirzepatide in obesity (2022) Randomized controlled trial

  Tirzepatide produced average weight loss of about 21% at the highest dose over 72 weeks, with 57% of that group losing at least a fifth of their body weight — territory previously reached only by bariatric surgery. As with STEP 1, this is a supervised trial with structured escalation and lifestyle support; and the DXA sub-study that answers the muscle question covered only 160 of the 2,539 participants.

  Source PMID 35658024

• SURMOUNT-5 — Aronne et al. (2025) — tirzepatide vs semaglutide in obesity, head to head (2025) Case series (uncontrolled)

  Given properly matched obesity doses of both drugs, tirzepatide produced roughly half again as much weight loss as semaglutide — 20.2% versus 13.7% — and a substantially larger waist reduction. This is the trial that settles the "which one works better for weight" question for these two molecules; it does not settle which is better on cardiovascular outcomes, where semaglutide has the SELECT evidence and tirzepatide does not. It was open-label, which is a real limitation for a trial whose primary endpoint is behaviour-sensitive.

  Source PMID 40353578

• Also in the record, in one line each

  - SURPASS-CVOT (Nicholls et al., 2025; n=13,299): tirzepatide was non-inferior but not superior to dulaglutide for cardiovascular death, MI or stroke in type 2 diabetes with atherosclerotic disease (12.2% vs 13.1%; HR 0.92, 95.3% CI 0.83–1.01; P=0.09 for superiority). Tirzepatide has no placebo-controlled cardiovascular outcome trial. DOI 10.1056/NEJMoa2505928

  Source PMID 40934115

Who it's for, who should skip

Cardiometabolic risk with elevated body fat or glucose. Constraints are cost, the injection format, and the need to pair with resistance training and adequate protein — otherwise a meaningful share of the weight lost is lean mass.

Running it

Form

injectable

Dose

weekly injection

Titration

titrate dose gradually to limit GI effects

What to expect

• Week 1–4 (initiation) — Nausea, and to a lesser extent vomiting, diarrhoea and constipation, are most frequent during initiation and each escalation step, and are described as typically transient and mild-to-moderate. Appetite suppression appears early. (Confidence: Trial-documented)
• Week 4–20 (escalation) — Weight curves separate from placebo within the first weeks and fall steeply through escalation. STEP 1 escalated over 16 weeks; SURMOUNT-1 over 20. Most treatment discontinuation for adverse events happens in this window. (Confidence: Trial-documented)
• Week 12–28 (glycaemic effect) — In type 2 diabetes, HbA1c falls by roughly 1.9–2.3 percentage points depending on agent and dose, with most of the change established well before the 40-week endpoint. (Confidence: Trial-documented)
• Week 40–72 (approach to plateau) — Weight loss continues but decelerates; STEP 1's curve was still descending at 68 weeks (−14.9%), SURMOUNT-1's at 72 weeks (−20.9% in the highest-dose arm). Neither trial demonstrated a completed plateau. (Confidence: Trial-documented)
• Year 2 (continued treatment) — STEP 5 (n=304, 104 weeks): −15.2% vs −2.6% on placebo, with 77.1% achieving ≥5% loss — i.e. the year-1 effect was maintained, not extended much further. GI adverse events were reported by 82.2% on semaglutide vs 53.9% on placebo across two years. (Confidence: Trial-documented)
• Continued vs withdrawn (randomized withdrawal) — SURMOUNT-4: after a 36-week open-label lead-in producing −20.9%, participants continuing tirzepatide lost a further 5.5% over 52 weeks while those switched to placebo regained 14.0%; 89.5% vs 16.6% maintained at least 80% of the lead-in loss. (Confidence: Trial-documented)
• After stopping (observational extension) — STEP 1 extension (n=327): one year off treatment, participants regained 11.6 of the 17.3 percentage points lost — about two-thirds — with cardiometabolic markers reverting toward baseline in parallel. (Confidence: Trial-documented (exploratory; the extension was not randomized and analyses were pre-specified as exploratory))
• Multi-year hard outcomes — SELECT: MACE reduction of 20% sustained over a mean 39.8 months of follow-up on continuous treatment. No comparable multi-year outcome data exist for intermittent or discontinued use. (Confidence: Trial-documented)
• Long term beyond ~4 years — Essentially unmeasured in randomized trials. The longest randomized exposures in this class are SELECT (mean 34.2 months) and SURPASS-CVOT; there is no randomized evidence about a decade of continuous use, which is what chronic weight management implies. (Confidence: No data)

Response signs

Getting it right

• Monitoring: Monitoring | What is monitored | What the record says | Source | |---|---|---| | Weight and waist | The primary endpoints of every obesity trial in; trials measured at fixed visits across 68–72 weeks | STEP 1 · SURMOUNT-1 | | HbA1c and fasting glucose | Primary and pre-specified endpoints in the diabetes programme; in non-diabetic populations FPG and fasting insulin were pre-specified in the STEP analyses | SURPASS-2 · DOI 10.1111/dom.14890 | | Blood pressure and lipids, and the medications treating them | The STEP analyses recorded a net reduction in antihypertensive and lipid-lowering medication use — meaning existing medications may need review as weight falls | DOI 10.1111/dom.14890 | | Resting heart rate | Increases by roughly 2–4.5 bpm depending on agent, consistently across the class | DOI 10.1186/s40001-026-03933-9 | | Retinal status in people with diabetes | SUSTAIN-6 found retinopathy complications increased in participants with pre-existing retinopathy undergoing rapid glucose lowering | SUSTAIN-6 | | Gallbladder symptoms | Risk elevated across the class and roughly doubled at weight-loss doses | DOI 10.1001/jamainternmed.2022.0338 | | Body composition | Only ever measured in small sub-studies (SURMOUNT-1 DXA: 160 of 2,539). No pivotal trial monitored lean mass routinely — which is why remains partly open | DOI 10.1111/dom.16275 | | Vision changes | EMA directs immediate medical contact for sudden vision loss and discontinuation if NAION is confirmed | EMA PRAC | mitigate side effect
• General safety — what trials and labels document: Gradual escalation is the mitigation. Both pivotal obesity trials built long escalation periods into the design — 16 weeks in STEP 1, 20 weeks in SURMOUNT-1 — and both reported that gastrointestinal adverse events occurred "primarily during dose escalation" and were "mostly mild to moderate" (STEP 1; SURMOUNT-1). Approved labelling builds in the same structure and includes explicit provisions for delaying an escalation step or reducing the dose when a step is not tolerated (Wegovy PI; Zepbound PI). SURMOUNT-5 went further and defined the assigned dose as the maximum tolerated dose (DOI 10.1056/NEJMoa2416394). mitigate side effect
• General safety — what trials and labels document: Antiemetics and symptomatic management are used clinically for the nausea and vomiting that dominate the adverse-event profile. This is standard practice rather than trial-tested strategy: no randomized trial in the class has tested an antiemetic co-treatment against control, and that gap should be stated rather than papered over. mitigate side effect
• General safety — what trials and labels document: Perioperative and pre-procedure handling is formally addressed. A 2024 multisociety clinical practice guidance — jointly issued by the American Society of Anesthesiologists with gastroenterology, bariatric and obesity-medicine societies — sets out how GLP-1 receptor agonists should be handled before elective procedures under sedation or general anaesthesia, given delayed gastric emptying and aspiration risk (DOI 10.1016/j.cgh.2024.10.003; ASA news release — society announcement, describing the peer-reviewed guidance rather than adding to it, so the two are one source and not two). Anyone on these drugs facing a procedure has a documented reason to raise it in advance. mitigate side effect
• General safety — what trials and labels document: Delayed gastric emptying affects other oral medicines. Tirzepatide labelling specifically addresses reduced efficacy of oral hormonal contraceptives, and oral semaglutide has strict fasting-administration requirements for its own absorption (Zepbound PI; OASIS 1). mitigate side effect
• General safety — what trials and labels document: Resistance training and protein intake for lean-mass preservation are the standard clinical recommendation, and the honest state of the evidence is in: the only randomized human trial pairing exercise with a GLP-1 used liraglutide, and found that adding supervised exercise roughly doubled the reduction in body-fat percentage compared with either alone (S-LiTE, DOI 10.1056/NEJMoa2028198). No equivalent trial exists for semaglutide or tirzepatide, and no trial has tested a protein target. There is also a signal that free-living physical activity may drift down on treatment (DOI 10.1038/s41366-026-02141-z) — which is the argument for making activity deliberate rather than assumed. mitigate side effect
• General safety — what trials and labels document: Product provenance is a safety variable, not a cost variable. FDA has documented five- to twenty-fold overdoses arising from compounded vial-and-syringe presentations and unit/millilitre confusion, with hospitalisations (FDA, 2024-07-26). USADA separately flags "generic" GLP-1 claims, patches, gummies, sublingual drops and "research use only" labelling as markers of unapproved product (USADA). mitigate side effect
• General safety — what trials and labels document: Stopping is a decision with documented consequences. Two-thirds of lost weight returned within a year in the STEP 1 extension, and cardiometabolic markers tracked back with it (DOI 10.1111/dom.14725). mitigate side effect
• The physician conversation: Which endpoint am I actually treating: weight, HbA1c, cardiovascular risk, sleep apnoea, liver disease, or kidney disease? Semaglutide and tirzepatide have different approved indications and different outcome evidence behind them. mitigate side effect
• The physician conversation: Given my history, does the cardiovascular outcome evidence (SELECT, semaglutide) or the weight magnitude evidence (SURMOUNT-5, tirzepatide) matter more? mitigate side effect
• The physician conversation: What is the escalation schedule, and what happens if I don't tolerate a step — is the plan to hold, to reduce, or to stop? mitigate side effect
• The physician conversation: Do I have a personal or family history of medullary thyroid carcinoma or MEN2, pancreatitis, gallstones, gastroparesis, or diabetic retinopathy? The MTC/MEN2 history is a labelled contraindication (Wegovy PI; Zepbound PI); each of the others changes the risk conversation. mitigate side effect
• The physician conversation: Am I on medications whose absorption or dosing may change — oral contraceptives, insulin or sulfonylureas, antihypertensives, lipid-lowering drugs? Tirzepatide labelling addresses reduced oral-contraceptive efficacy and both labels address concomitant insulin and insulin secretagogues (Wegovy PI; Zepbound PI), and the STEP analyses recorded a net reduction in antihypertensive and lipid-lowering medication use as weight fell (DOI 10.1111/dom.14890). mitigate side effect
• The physician conversation: How will lean mass, strength and nutritional adequacy be tracked, given that no pivotal trial tracked them routinely? mitigate side effect
• The physician conversation: Do I have a procedure or surgery coming up, and what does the perioperative guidance say for my situation? mitigate side effect
• The physician conversation: What is the plan if I stop — is this framed as a chronic therapy, and what happens to my weight and my other prescriptions if it ends? mitigate side effect
• The physician conversation: Is the product I will receive an FDA-approved presentation, and if it is not, what exactly is the concentration and who verified it? mitigate side effect

Measuring it

Retest HbA1c — Quarterly while titrating or not at goal, every 6 months once stable — monitor body composition, not just weight..

• HbA1c baseline
• HbA1c quarterly
• Fasting glucose baseline
• Fasting glucose on cycle
• LDL-C baseline
• LDL-C annual
• Triglycerides baseline
• Triglycerides annual

How biomarkers respond

• Resting heart rate May deteriorate · Trial durations, 12 articles — ↑ ~3.5 bpm across the class (semaglutide +3.35, 95% CI 1.69–5.01; tirzepatide +2.05, 95% CI 0.96–3.13; oral semaglutide +4.50) — Trial-documented (pairwise and network meta-analysis in non-diabetic overweight/obese populations) (DOI 10.1186/s40001-026-03933-9) Trial-documented

Safety

• GI effects (nausea, vomiting, constipation), especially during escalation common
• pancreatitis, gallbladder disease rare
• lean-mass loss without resistance training and adequate protein

Stacking & alternatives

• Escalation from Retatrutide — The next step up in the same lineage, with phase 2 loss of −24.2% at 48 weeks (a figure carried across from the `retatrutide` dossier and not separately cited in this file) but no approval anywhere and no lawful route. Read the `retatrutide` dossier alongside this one; that dossier's treats this file as its primary comparator

Pair it with

• resistance training + adequate protein (≥1.6 g/kg/day) — GLP-1s cause lean-mass loss without resistance training and adequate protein; both are needed to preserve muscle. required · ongoing

• Resistance Training
• Increase Protein Intake

Access & cost

Prescription or clinician order — typically via endocrinology or primary care.

A lawful channel exists, so this section reports real prices. All figures are US, from manufacturers' own programmes or from published pricing reporting, and are dated — this is the fastest-moving section in the dossier. No vendor beyond the manufacturers' own direct programmes is named anywhere, and no compounded-product pricing is recorded. US list prices (wholesale acquisition cost). Lilly's published list price for a 28-day supply of Zepbound was reported in January 2026 as ranging from $499 to $1,086 depending on presentation (GoodRx, updated 2026-05-18). Novo Nordisk announced on 2026-02-24 that it will cut the US list price of Wegovy, Ozempic and Rybelsus to $675 per month, stated as effective 2027-01-01 — described as an approximately 50% reduction for Wegovy and approximately 35% for Ozempic and Rybelsus, which implies pre-cut list prices of roughly $1,350 and roughly $1,040 respectively (Novo Nordisk, 2026-02-24 — per sponsor announcement). ⚠️ This is a company statement of pricing intent, not a completed event and not a third-party confirmation; whether it takes effect. The two implied pre-cut figures are this dossier's own arithmetic from the announced percentages, not sourced prices. ⚠️ Note that Novo's release states the list-price change "does not have an impact on direct-to-patient, self-pay prices" — the two channels move independently. Manufacturer direct-to-consumer self-pay. This is where most cash-paying patients now transact, and the figures are far below list. The NovoCare rows are the manufacturer's own statements about its own prices; the LillyDirect and Ozempic rows are reported by trade press. The dates on which the manufacturer says it will revisit these prices are not printed as body prose here — because a date embedded in a table silently expires while the table goes on looking current. ⚠️ The strengths named in the table below identify which approved product presentation a price applies to — a regulatory product record, not an administered exposure and not a schedule. Every administered human quantity in this dossier lives in. Zepbound single-dose vials, 2.5 mg — $299/month (reduced from $349) — LillyDirect only — Fierce Pharma, 2025-12-01 Zepbound single-dose vials, 5 mg — $399/month (reduced from $499) — LillyDirect only — Fierce Pharma, 2025-12-01 Zepbound single-dose vials, 7.5–15 mg — $449/month (reduced from $499) — LillyDirect only — Fierce Pharma, 2025-12-01 Wegovy pen — $349/month; $199/month for the first two months for new patients — NovoCare Pharmacy, plus retail/telehealth partners — NovoCare — manufacturer's own page, self-asserted; that page's stated revisit date Wegovy HD pen (7.2 mg) — $399/month — NovoCare Pharmacy — NovoCare — manufacturer's own page, self-asserted Wegovy pill (oral semaglutide) — from $149/month — NovoCare Pharmacy — NovoCare — manufacturer's own page, self-asserted; that page's stated revisit date Ozempic — $349/month for most presentations; $499 for the 2 mg pen — NovoCare and partner channels — Fierce Pharma, 2025-12-01 With commercial insurance, Novo's savings offer advertises as little as $25/month with a $100/month maximum benefit, at participating pharmacies (NovoCare — manufacturer's own page, self-asserted). ⚠️ Every NovoCare figure in this section is the vendor describing its own prices, including the dates on which it says those prices will be revisited; none is confirmed by a third party. The Lilly and Ozempic self-pay figures below and above come from trade journalism, which is a different and independent class of source. Coverage for the obesity indication remains far narrower than for the diabetes indication, which is why the self-pay channel exists at all. The compounded picture, and why it is no longer a price comparison. During the 2022–2025 shortages, compounded semaglutide and tirzepatide were widely dispensed at a fraction of brand prices. FDA declared the tirzepatide shortage resolved on 2024-10-02 and the semaglutide shortage resolved on 2025-02-21, with compounding cutoffs of 2025-02-18/2025-03-19 (tirzepatide, 503A/503B) and 2025-04-22/2025-05-22 (semaglutide, 503A/503B) (FDA). FDA's position is that it "may still take action regarding violations of any other statutory or regulatory requirements," and its 2024 alert documents the concrete harm — five- to twenty-fold dosing errors and hospitalisations (FDA). No compounded price figure is recorded in this dossier, because doing so would function as a price comparison between an approved product and material whose identity and strength are unverified. The manufacturer self-pay prices above have moved into the same order of magnitude in any case. ---

Questions

Does semaglutide actually work for weight loss if you don't have diabetes?

Yes, and this is one of the few compounds in this library where that can be said flatly. In STEP 1 — 1,961 adults with obesity and no diabetes, randomized and placebo-controlled over 68 weeks — mean weight change was −14.9% versus −2.4% on placebo, with 50.5% losing at least 15% of body weight (DOI 10.1056/NEJMoa2032183). SELECT then showed the same drug reduced cardiovascular death, heart attack and stroke by 20% in a similar non-diabetic population with existing heart disease (DOI 10.1056/NEJMoa2307563).

Which is better, Ozempic/Wegovy or Mounjaro/Zepbound?

For weight, the head-to-head answer is tirzepatide. SURMOUNT-5 randomized 751 adults with obesity and without diabetes to maximum tolerated doses of each for 72 weeks: −20.2% with tirzepatide vs −13.7% with semaglutide (DOI 10.1056/NEJMoa2416394). For cardiovascular outcomes the answer runs the other way on current evidence: semaglutide has a positive placebo-controlled outcome trial (SELECT), while tirzepatide's outcome trial showed non-inferiority to dulaglutide without demonstrating superiority (DOI 10.1056/NEJMoa2505928). "Better" depends on which endpoint you are buying.

How long until it starts working?

Appetite effects and GI side effects appear within the first weeks, and weight curves separate from placebo early — but the labelled escalation to a maintenance dose takes 16 weeks for semaglutide and up to 20 weeks for tirzepatide, and in both pivotal trials the weight curve was still falling at 68–72 weeks (STEP 1; SURMOUNT-1). The trials are 16-month experiments, not 8-week ones.

Is the pill as good as the shot?

Closer than the marketing framing of "pills are weaker" suggests, but the comparison has to be dose-matched. The higher of the two oral strengths studied in the OASIS programme produced −15.1% at 68 weeks in OASIS 1, alongside −2.4% on placebo — squarely in the territory of the injectable's weight-management dose (DOI 10.1016/S0140-6736(23)01185-6). The presentation approved on 2025-12-22 is the Wegovy tablet, under NDA 218316 (original submission ORIG 1, approved 2025-12-22, submission class Type 3 — New Dosage Form; approved strengths 1.5 / 4 / 9 / 25 mg), and its trial is published: in OASIS 4 (n=307, randomized 2:1, 71 weeks) the estimated mean weight change to week 64 was −13.6% versus −2.2% on placebo (difference −11.4 percentage points, 95% CI −13.9 to −9.0; P<0.001), with gastrointestinal adverse events in 74.0% versus 42.2% (DOI 10.1056/NEJMoa2500969 · PMID 40934115 · NCT05564117). ⚠️ These figures replace the approximate ones this file carried until 2026-08-29. Those — roughly −17% and roughly −14% on two different analyses — came from Novo Nordisk's announcement, which was then the only source for the trial. The peer-reviewed report supersedes them and they are not restated here. ⚠️ The approval event itself was carried by the sponsor's announcement alone until 2026-08-29 and is now sourced to Drugs@FDA — NDA 218316, ORIG 1, approved 2025-12-22 — so nothing in this answer depends on the announcement any more. Do not confuse the products. The obesity indication on an oral semaglutide product belongs to WEGOVY tablets under NDA 218316. The other oral semaglutide tablets — RYBELSUS, and the OZEMPIC-branded oral tablets at 1.5 / 4 / 9 mg, both under NDA 213051 — are indicated on the current label for type 2 diabetes glycaemic control and cardiovascular risk reduction in type 2 diabetes only, with no weight-management indication. "An oral semaglutide pill" is therefore not one thing: which application the tablet sits on determines what it is approved to treat. What no oral form has is an equivalent of SELECT run on the oral formulation. Note also the absorption constraint: oral semaglutide must be taken fasting with a small sip of water and nothing else for at least 30 minutes, which is a real adherence burden the injectable does not have. ⚠️ Where marketing outruns data most is with non-injectable, non-tablet formats — "oral drops", sublingual sprays, patches, gummies. USADA lists exactly those formats as red flags for unapproved product (USADA); no such format has published bioavailability or efficacy data.

What happens when you stop?

You regain, on the documented average, most but not all of it. In the STEP 1 extension participants regained 11.6 of 17.3 percentage points within a year of stopping (DOI 10.1111/dom.14725); in SURMOUNT-4's randomized withdrawal, people switched to placebo regained 14.0% while those continuing lost a further 5.5% (DOI 10.1001/jama.2023.24945). Cardiometabolic improvements track the weight back up.

Do they cause hair loss?

Hair shedding is a well-recognised consequence of rapid weight loss generally (telogen effluvium), and it is not on the pivotal trials' common-adverse-event lists. A disproportionality analysis of FDA's adverse-event reporting system found alopecia reported more often than expected for semaglutide (DOI 10.1111/jdv.20197). ⚠️ Disproportionality analyses detect reporting signals; they cannot estimate incidence, cannot establish causation, and are highly sensitive to media attention — which for this class was extreme. Evidence class: signal only.

Do you lose muscle, and does lifting prevent it?

About a quarter of the weight lost was lean mass in the SURMOUNT-1 DXA sub-study — the same proportion as in the placebo group (DOI 10.1111/dom.16275). Whether training prevents it has not been tested in a randomized trial with semaglutide or tirzepatide; the nearest evidence is S-LiTE, where adding supervised exercise to liraglutide roughly doubled the reduction in body-fat percentage compared with either alone (DOI 10.1056/NEJMoa2028198). See — this is the batch's most-asked question and the answer is partly open.

Is "microdosing" a GLP-1 for longevity a real thing?

It is a real practice with no trial behind it. Science News reported in March 2026 that around one in seven users microdoses, and quoted specialists stating there is no rigorous scientific data supporting it (2026-03-20). Every efficacy and safety figure in this dossier comes from trials of labelled maintenance doses in people meeting BMI entry criteria. Nothing in or transfers to a sub-label dose taken by a metabolically healthy person. ---