Semaglutide: Ozempic/Wegovy weight-loss & diabetes drug
A prescription drug that mimics a natural fullness hormone, telling the brain you're full; lowers blood sugar and causes significant weight loss. FDA-approved.
- Class
- GLP-1 receptor agonist
- Status
- FDA-approved prescription drug (Ozempic 2017, Rybelsus 2019, Wegovy 2021, Wegovy MASH 2025, Oral Wegovy late 2025); also authorized in EU, UK, Canada, and Australia
- Best-supported effect
- ~15% mean body-weight reduction at 2.4 mg weekly over 68 weeks (STEP-1); HbA1c reduction in type 2 diabetes (SUSTAIN); 20% relative MACE reduction in adults with overweight/obesity and established CV disease (SELECT)
- Main caveat
- Benefits are tied to ongoing therapy — STEP-4 and STEP-1 extension data show roughly two-thirds of lost weight is regained within a year of discontinuation. GI adverse events are common, and the EVOKE / EVOKE+ Phase 3 readout in early Alzheimer's disease was negative.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
FDA-approved drug — commercial manufacture documented
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FDA-approved — Phase 3 efficacy and receptor activity established
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What this is
Semaglutide is a prescription medication that mimics GLP-1, a natural gut hormone that signals fullness after eating. Sold under the names Ozempic and Rybelsus (type 2 diabetes) and Wegovy (weight management), it is FDA-approved and one of the most widely prescribed peptide drugs in medicine. It is a 31-residue modified GLP-1 analog developed by Novo Nordisk; two chemical changes extend the half-life from minutes (native GLP-1) to roughly one week — an aminoisobutyric acid substitution at position 2 that blocks enzymatic cleavage, and a C-18 fatty diacid side chain at position 26 that enables reversible albumin binding. The raw stored sequence (HAEGTFTSDVSSYLEGQAAKEFIAWLVRGRG) represents the bare amino acid backbone; neither the fatty diacid chain nor the modified residue at position 2 appears in this one-letter rendering.
History
Semaglutide was developed by Novo Nordisk as a structural successor to liraglutide, designed to extend GLP-1 receptor agonism from once-daily to once-weekly dosing. The FDA approved Ozempic for type 2 diabetes in December 2017 following the SUSTAIN trial program. Rybelsus — the first oral GLP-1 agonist — received approval in September 2019, enabled by co-formulation with the absorption enhancer SNAC. Wegovy, at the higher 2.4 mg dose for chronic weight management, followed in June 2021. In March 2024 Wegovy's label was extended to include reduction of major adverse cardiovascular events in adults with overweight or obesity and established cardiovascular disease, based on the SELECT trial. In August 2025 the FDA granted accelerated approval for a MASH (non-cirrhotic, stage 2–3 fibrosis) indication, and an oral 25 mg Wegovy tablet was approved in late 2025.
What it does
In simple terms, semaglutide tells the brain you are full, slows the rate at which food leaves the stomach, and prompts the pancreas to release insulin when blood sugar rises — but only when blood sugar is actually elevated, which limits the risk of hypoglycemia on its own. The practical result is reduced appetite, lower food intake, weight loss, and improved blood sugar control. Large Phase 3 trials also demonstrated cardiovascular and kidney-protective effects that extend beyond what weight loss alone explains (Wilding et al., NEJM 2021; McGuire et al., NEJM 2025).
Evidence
- Human: Extensive Phase 3 trial evidence across multiple programs. The STEP program (obesity; STEP-1 published Wilding et al., NEJM 2021) showed a mean 14.9% body-weight reduction at 68 weeks versus 2.4% on placebo in adults with overweight or obesity. STEP-4 (Rubino et al., JAMA 2021) demonstrated weight-loss maintenance with continuation and roughly two-thirds regain within a year of stopping. SUSTAIN-6 (Marso et al., NEJM 2016) showed a 26% relative reduction in major adverse cardiovascular events in high-risk type 2 diabetes. SELECT (Lincoff et al., NEJM 2023) extended this to a 20% relative MACE reduction in 17,604 adults with overweight or obesity but without diabetes. FLOW (Perkovic et al., NEJM 2024) reported a 24% relative reduction in kidney disease progression in type 2 diabetes with CKD. ESSENCE part 1 (Sanyal et al., NEJM 2025) showed 63% MASH resolution versus 34% on placebo, forming the basis for the 2025 MASH indication. STEP-HFpEF showed improvement in heart failure symptoms and body weight in heart failure with preserved ejection fraction. EVOKE and EVOKE+ (Phase 3, oral semaglutide 14 mg versus placebo, n=3,808, adults aged 55–85 with mild cognitive impairment or mild Alzheimer's disease) reported no slowing of CDR-SB progression at their topline readout in November 2025 — the first major negative Phase 3 result for semaglutide. The SOUL trial (oral semaglutide in high-risk type 2 diabetes, McGuire et al., NEJM 2025) demonstrated cardiovascular benefit; secondary analyses extended evidence to heart failure outcomes and durable multi-factor CV risk reduction over approximately four years. One randomized trial in adults with alcohol use disorder showed an exploratory signal for reduced alcohol consumption (not a Phase 3 efficacy program).
- Animal: Comprehensive; GLP-1 biology is among the most studied metabolic pathways. Rodent studies identified a thyroid C-cell carcinogenicity signal that underlies the drug's boxed warning; no equivalent human signal has been detected in the trialed windows.
- In vitro / mechanistic: GLP-1 receptor pharmacology and downstream cAMP/PKA/Epac2 signaling in pancreatic beta cells are well-characterized.
Known effects
- Weight loss (~15% mean body weight at 2.4 mg weekly over 68 weeks) — FDA-approved (Wegovy; STEP trials)
- Blood sugar control in type 2 diabetes — FDA-approved (Ozempic, Rybelsus; SUSTAIN, PIONEER trials)
- Reduction of major adverse cardiovascular events — FDA-approved (SELECT, SUSTAIN-6); both in T2D populations and in adults with obesity without diabetes
- Kidney disease progression slowing in T2D + CKD — Phase 3 (FLOW)
- MASH resolution (non-cirrhotic, stage 2–3 fibrosis) — FDA accelerated approval (ESSENCE, August 2025)
- Heart failure symptom improvement (HFpEF) — Phase 3 (STEP-HFpEF)
- Walking capacity improvement in T2D + peripheral artery disease — Phase 3 (STRIDE)
- Reduction of Parkinson's disease risk (class-level, GLP-1 agonists) — Observational; a meta-analysis of 82 studies reports a roughly 30% lower risk association for GLP-1 receptor agonists as a class; this is not a semaglutide-specific causal finding
- Alzheimer's disease modification — Contradicted at Phase 3 level; EVOKE / EVOKE+ were negative
Safety signals
Nausea is the most common adverse event — reported in approximately 40–44% of participants across Phase 3 trials, typically transient and attenuating within the first several weeks. Vomiting (~24%), diarrhea (~30%), constipation (~24%), and abdominal pain (~20%) were also common in trials. Aggregate gastrointestinal adverse events in STEP-1 affected 74.2% of the semaglutide group versus 47.9% on placebo (Wilding et al., NEJM 2021).
Acute pancreatitis is rare (less than 1%) but documented; risk is elevated in those with a prior history. Gallbladder events (cholecystitis) occurred in approximately 1.6% of trial participants, with higher incidence at higher doses and during periods of rapid weight loss. Acute kidney injury has been reported rarely, typically associated with dehydration secondary to GI adverse events. Hypoglycemia risk rises substantially when semaglutide is combined with insulin or insulin secretagogues; labeling addresses downward titration of the concomitant agent.
Body-composition sub-studies consistently show that approximately 25–40% of lost weight comes from lean tissue; this is broadly comparable to other methods of equivalent weight loss.
Post-marketing surveillance has tracked severe gastroparesis (rare; subject of multidistrict litigation since 2023), early signals of suicidal ideation (not confirmed in large pharmacovigilance analyses), and diabetic retinopathy progression. Delayed gastric emptying alters the absorption of orally co-administered narrow-therapeutic-index drugs including warfarin and levothyroxine.
Label contraindications / safety exclusions:
- Personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2) — boxed warning; based on rodent C-cell tumor findings; human causal link not established in trialed windows
- Prior serious hypersensitivity reaction to semaglutide
- Active pancreatitis or history of recurrent pancreatitis
- Pregnancy (animal reproductive toxicity data; labeling describes discontinuation at least 2 months before a planned pregnancy)
- Breastfeeding (transfer into human milk not adequately characterized)
- Severe gastroparesis or significant GI motility disorders
- Pediatric use below approved age cutoffs (Wegovy approved for adolescents ≥12; Ozempic and Rybelsus not approved under 18)
Regulatory status
- US (FDA): Approved prescription drug. Ozempic (December 2017, type 2 diabetes); Rybelsus (September 2019, oral type 2 diabetes); Wegovy (June 2021, chronic weight management in adults and adolescents ≥12); Wegovy label expanded March 2024 for MACE reduction in adults with established cardiovascular disease and overweight or obesity; Wegovy accelerated approval August 2025 for non-cirrhotic MASH with stage 2–3 fibrosis; oral Wegovy 25 mg approved late 2025. No FDA-approved generic semaglutide products as of early 2026.
- EU (EMA): Ozempic, Rybelsus, and Wegovy authorized for parallel indications.
- UK (MHRA): Approved; NHS coverage of Wegovy is subject to NICE criteria.
- Canada (Health Canada): Authorized for parallel indications.
- Australia (TGA): Authorized for parallel indications.
- WADA: Not currently listed by name on the WADA Prohibited List; increasing scrutiny of GLP-1 agonists in weight-category sports is described in the literature.
- US compounding: Following removal of the FDA shortage designation in February 2025, traditional 503A pharmacy compounding of semaglutide is no longer permitted outside narrowly defined clinical circumstances. Some compounded products have used semaglutide salts (sodium, acetate) that are structurally distinct from the base peptide in the approved drugs.
Mechanism
Semaglutide is an agonist at the GLP-1 receptor, a Class B G-protein-coupled receptor expressed on pancreatic beta cells, in hypothalamic nuclei (notably the arcuate nucleus), and in the brainstem area postrema.
In pancreatic beta cells, receptor activation raises intracellular cAMP, which drives PKA/Epac2 signaling and enhances glucose-dependent insulin secretion — meaning insulin release is amplified only when blood glucose is elevated, limiting intrinsic hypoglycemia risk. The drug also suppresses glucagon secretion from pancreatic alpha cells and slows gastric emptying, prolonging post-meal satiety.
Centrally, GLP-1 receptor activation in hypothalamic and brainstem appetite-control centers reduces hunger and reward-driven eating. Brain-imaging data cited in the literature are consistent with reduced neural responses to food cues, corresponding to what users describe as quieting of "food noise."
The C-18 fatty diacid side chain at lysine 26 — linked through a γ-glutamic acid spacer that is not represented in the stored sequence — mediates non-covalent reversible albumin binding, extending half-life from minutes (native GLP-1) to approximately one week and enabling once-weekly subcutaneous dosing. The aminoisobutyric acid substitution at position 2 protects the peptide from DPP-4 cleavage.
Direct cardiovascular and renal protective effects beyond weight and glycemic improvement are described in the literature, including slower eGFR decline, reduced proteinuria, and anti-inflammatory signals in the cardiovascular system.
Open questions
- Long-term outcomes: Cardiovascular, renal, oncologic, and metabolic data beyond the approximately 5-year SELECT and SOUL windows are not yet available.
- Continuation and cycling: Optimal strategies for indefinite chronic therapy — whether dose holidays preserve efficacy without triggering weight regain — are not resolved in trial data.
- Body composition: The optimal combination of resistance training, protein intake, and adjunctive pharmacology to mitigate lean-mass loss during rapid weight loss is not rigorously defined.
- Underrepresented populations: Older adults with frailty, patients with advanced CKD, and pediatric populations below current age cutoffs are underrepresented in pivotal trials.
- Neuropsychiatric signals: Post-marketing concerns about suicidal ideation are unconfirmed but warrant ongoing surveillance.
- Neurodegeneration: With EVOKE / EVOKE+ negative for early symptomatic Alzheimer's, the mechanism and clinical relevance of GLP-1 agonism in neurodegeneration — including the class-level Parkinson's-risk observational signal — remain unresolved.
- Addiction medicine: Whether the alcohol-use-disorder signal from one RCT extends to a regulatory-grade indication is unanswered.
Related peptides
- Liraglutide — the predecessor once-daily GLP-1 agonist that semaglutide was engineered to replace; same GLP-1 receptor target, shorter half-life, no dedicated obesity-dose approval
- Tirzepatide (Mounjaro, Zepbound) — dual GIP/GLP-1 receptor agonist; produces greater mean weight loss than semaglutide in head-to-head Phase 3 comparisons
- Retatrutide — triple GIP/GLP-1/glucagon receptor agonist in late-stage development; next-generation incretin approach
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Does semaglutide reduce the urge to drink by quieting a brain reward signal triggered by alcohol cues, in a way that has nothing to do with losing weight?
If true, the weekly Ozempic/Wegovy injection could become a new treatment for alcohol use disorder, helping people avoid relapse even if they are not overweight. For the 280 million people worldwide affected by alcohol addiction, a drug with this already-established safety record could be a meaningful option where very few exist today.
Does the oily side-chain on semaglutide lock the drug's receptor into a state that sends a stronger, longer "fullness" signal compared to related drugs that lack that chain?
If this mechanism is confirmed, drug designers could build next-generation weight-loss drugs by deliberately shaping that fatty side-chain rather than just tweaking how long the drug stays in the body. That could unlock treatments that work better, hit a higher weight-loss ceiling, and help the millions of people for whom current options are not effective enough.
Does semaglutide protect brain cells only when enough healthy connections still remain, meaning it could prevent Alzheimer's but cannot reverse it once the disease is already established?
If this holds, the recent failed Alzheimer's trial would not mean the drug is useless for the brain; it would mean it was tested too late. People who are genetically at risk but still cognitively normal could potentially benefit from early treatment, representing a huge unmet need where no preventive options currently exist.
Does semaglutide directly block the liver cells that form scar tissue, in a way that works even in patients who do not lose much weight on the drug?
If the drug directly halts liver scarring rather than only helping through weight loss, it could work for a much broader group, including patients with advanced liver damage currently excluded from treatment, and those with liver disease caused by alcohol rather than obesity. That would expand a newly approved treatment to far more people who currently have no good options.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.9244879484176636 | boltz-2 |
| ranking score | 0.7912138104438782 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.866 | global PDE — lower = better |
| disorder | NaN | fraction disordered |
▸3-letter notation
▸recipeboltz-2 1.0
| parameter | value |
|---|---|
| model | boltz-2 1.0 |
| weights | — |
| hardware | nvidia_nim_api |
| mlx version | — |
| python | — |
| random seed | — |
| msa strategy | none |
| diffusion samples | 1 |
| runtime | — |
| predicted by | mlx@peptide |
| predicted at | 2026-04-24 |
▸citationbibtex
@peptide{pep00016,
sequence = {HAEGTFTSDVSSYLEGQAAKEFIAWLVRGRG},
target = {glp-1r},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}