Oxyntomodulin: natural gut hormone behind dual weight-loss drugs
A hormone released after meals that suppresses appetite and boosts calorie burning; the natural blueprint for newer obesity drugs like survodutide and retatrutide, but not itself an approved drug.
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.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
Oxyntomodulin (also called glucagon-37, or OXM) is a 37-amino-acid gut hormone released after meals from L cells of the small intestine. It is the natural pharmacological prototype for the modern "dual agonist" obesity drug class — it activates two receptors at once, the GLP-1 receptor (the same target as semaglutide) and the glucagon receptor. The combination produces appetite suppression plus a small increase in energy expenditure, the dual mechanism that drug developers later engineered into longer-acting analogs such as cotadutide, survodutide, mazdutide, and the glucagon arm of retatrutide. OXM itself has never been approved as a drug: its half-life is on the order of minutes, and at the receptor it is roughly 10–100× less potent than the selective endogenous agonists glucagon and GLP-1 (Pocai, Molecular Metabolism 2014; Lafferty et al., Frontiers in Endocrinology 2021).
OXM is one of several peptides cleaved from the proglucagon precursor (GCG gene). Tissue-specific processing decides which fragments are released: pancreatic alpha cells use prohormone convertase 2 and release the 29-residue glucagon; intestinal L cells use prohormone convertase 1/3 and release glicentin, OXM, GLP-1 and GLP-2 together into the portal circulation in proportion to the meal (Lafferty et al. 2021; Gasbjerg et al., Physiological Reviews 2026). Structurally, OXM is the full 29-residue glucagon sequence (HSQGTFTSDYSKYLDSRRAQDFVQWLMNT) with an 8-residue C-terminal extension from the proglucagon "IP-1" region (KRNRNNIA in human, mouse and rat); that C-terminal tail is what adds GLP-1 receptor activity to glucagon's intrinsic GCGR activity and gives OXM its dual profile. The stored 37-letter sequence is a free-acid peptide — unlike GLP-1(7-36)-amide, OXM is not C-terminally amidated, and unlike the engineered analogs (cotadutide, survodutide, retatrutide) it carries no fatty-acid acylation or other half-life-extending modification, which is the principal reason its circulating half-life is so short.
History
Through the 1960s and 1970s, gut extracts contained a glucagon-like immunoreactivity ("enteroglucagon") that differed in molecular weight and bioactivity from pancreatic glucagon but resisted clean chemical characterization. Bataille and colleagues at INSERM in Paris, working with Tatemoto and Mutt at the Karolinska Institute, finally resolved the molecular identity: they isolated a 37-residue peptide from porcine jejuno-ileum and sequenced it as glucagon(1-29) with an 8-residue C-terminal extension (Bataille et al., FEBS Letters 1982). The name "oxyntomodulin" came from its original assayed activity — inhibition of acid secretion from the oxyntic (acid-secreting) cells of the stomach. Follow-up work established that OXM and glicentin (proglucagon 1–69) were distinct intestinal proglucagon products, and that OXM, not glicentin, carries the bulk of the bioactivity.
The modern therapeutic chapter was driven primarily by Stephen Bloom's group at Imperial College London in the early 2000s. They first showed in humans that intravenous OXM acutely suppresses appetite and reduces food intake at a test meal, and then ran the foundational four-week randomized controlled trial: subcutaneous OXM administered three times daily before meals produced 2.3 ± 0.4 kg mean weight loss in overweight and obese volunteers, compared with 0.5 ± 0.5 kg on placebo, with energy intake at the study meal reduced by roughly 25–35% (Wynne et al., Diabetes 2005). A crossover follow-up established that OXM also increases resting energy expenditure (Wynne et al., International Journal of Obesity 2006), demonstrating the dual mechanism — appetite suppression plus raised energy expenditure — that distinguishes dual agonism from selective GLP-1 agonism.
Parallel preclinical work characterized the receptor dependence of these effects. Peripheral OXM in rats reduces food intake and body weight gain, and co-administration of the GLP-1 receptor antagonist exendin(9-39) abolishes the food-intake reduction, locating the satiety component at GLP-1R (Dakin et al., Endocrinology 2001). The glucagon-receptor side of the molecule contributes separately to thermogenesis and hepatic fat oxidation (Scott et al., Peptides 2018). These findings reframed OXM as the natural pharmacological proof-of-concept for "balanced GLP-1/glucagon co-agonism" — a strategy that the pharmaceutical industry then engineered into longer-acting analogs with extended half-lives, culminating in cotadutide (MEDI0382, AstraZeneca), survodutide (BI 456906, Boehringer Ingelheim, Phase 3), mazdutide (Innovent, approved in China), and the GCGR arm of retatrutide (LY3437943, Eli Lilly, Phase 3) (Lafferty et al. 2021; Gasbjerg et al. 2026).
What it does
Dual GLP-1R and GCGR agonism at modest potency. OXM activates both receptors but with roughly 10–100× lower potency than the selective endogenous agonists at each (GLP-1 at GLP-1R, glucagon at GCGR). Both are class B G-protein-coupled receptors that signal predominantly through Gαs/adenylyl-cyclase/cAMP. The combination produces a pharmacology no selective agonist can reproduce: GLP-1R activation contributes glucose-dependent insulin secretion, delayed gastric emptying, and appetite suppression; GCGR activation contributes hepatic glycogenolysis, hepatic fat oxidation, and increased resting energy expenditure (Pocai 2014; Graaf et al., Pharmacological Reviews 2016; Gasbjerg et al. 2026).
Appetite suppression — GLP-1R-mediated. OXM reduces food intake when administered peripherally (intraperitoneal or subcutaneous) in rodents, and reduces caloric intake in humans when administered subcutaneously before meals. The anorectic effect is blocked by the GLP-1R antagonist exendin(9-39), pinning this component on GLP-1R rather than GCGR (Dakin et al. 2001). The signal is transmitted both centrally — to hypothalamic arcuate-nucleus and brainstem satiety circuits — and via vagal afferent fibers in the gut wall.
Increased energy expenditure — GCGR-mediated. Unlike GLP-1, OXM raises resting energy expenditure. In humans, the Bloom group documented a measurable increase in energy expenditure during OXM administration (Wynne et al. 2006). In preclinical work, an OXM analog's effect on energy expenditure was abolished by glucagon-receptor antagonism, localizing this component to GCGR (Scott et al. 2018). The combination of reduced caloric intake and raised energy expenditure produces greater weight loss in preclinical models than either mechanism alone — the pharmacological rationale that drove the dual-agonist drug-discovery programs.
Glucoregulatory effects independent of weight loss. An intravenous infusion of native OXM in obese subjects with and without type 2 diabetes produced measurable changes in insulin secretion rate and glycaemic excursion during a graded glucose infusion — effects observable on the order of hours, distinct from the longer-timescale benefits of weight loss itself (Shankar et al., Diabetes 2018). This is consistent with the dual-receptor mechanism: GLP-1R activity contributes glucose-dependent insulin secretion while GCGR activity raises hepatic glucose output, with net effect depending on glycaemic context.
Why native OXM is not itself a drug. Three properties stand in the way of native OXM as a chronic therapy: low receptor potency (10–100× weaker than selective agonists), rapid degradation by dipeptidyl peptidase-4 (DPP-4 cleaves the N-terminal His¹-Ser² bond) and neutral endopeptidase, and a circulating half-life on the order of minutes. The engineered dual-agonist analogs address all three with N-terminal substitutions to resist DPP-4, fatty-acid acylation or other half-life-extending modifications, and sequence optimisation for higher potency and tuned GLP-1R/GCGR balance (Lafferty et al. 2021).
Evidence
- Human: A four-week double-blind, placebo-controlled randomized trial (Wynne et al., Diabetes 2005) reported 2.3 ± 0.4 kg weight loss on thrice-daily subcutaneous OXM versus 0.5 ± 0.5 kg on placebo (P = 0.0106), with reduced energy intake (25–35%) at the test meal. A crossover follow-up (Wynne et al., International Journal of Obesity 2006) showed OXM also increases energy expenditure. A separate randomized infusion study in obese subjects with and without type 2 diabetes documented OXM's glucoregulatory effects as independent of weight loss (Shankar et al., Diabetes 2018). Human trials of native OXM are uniformly short (days to weeks) and small (tens of subjects); there is no Phase 3 program for native OXM. The clinical translation of the dual-agonist rationale has been via engineered analogs — cotadutide reached Phase 2a (Ambery et al., Lancet 2018) and Phase 3 programs are ongoing for survodutide and retatrutide.
- Animal: Peripheral OXM reduces food intake and body weight gain in rats; the anorectic component is GLP-1R-dependent and abolished by exendin(9-39) (Dakin et al., Endocrinology 2001). An OXM-based analog increases energy expenditure via the glucagon receptor in rodent models (Scott et al., Peptides 2018). The same dual-receptor preclinical pharmacology underwrote the medicinal-chemistry programs that produced cotadutide, survodutide, mazdutide and retatrutide.
- In vitro / mechanistic: The cloning of the human glucagon receptor (MacNeil et al., Biochemical and Biophysical Research Communications 1994) and the broader characterisation of class B GPCR pharmacology of GLP-1R and GCGR (Graaf et al., Pharmacological Reviews 2016) provide the receptor framework. Comprehensive reviews of proglucagon-derived-peptide pharmacology and the dual-agonist drug class are available (Pocai, Molecular Metabolism 2014; Lafferty et al., Frontiers in Endocrinology 2021; Gasbjerg et al., Physiological Reviews 2026).
Myths and misconceptions
- "Oxyntomodulin is just a weaker form of glucagon." OXM contains glucagon(1-29) but its receptor profile is qualitatively different, not merely weaker. Glucagon is a potent, selective GCGR agonist with minimal GLP-1R activity; OXM activates both GCGR and GLP-1R, and its anorectic effect is GLP-1R-mediated — an effect glucagon alone does not produce. The 8-residue C-terminal extension shifts the pharmacology rather than just attenuating it (Pocai 2014; Dakin et al. 2001).
- "OXM and glicentin are the same molecule." Both are intestinal proglucagon products and co-secreted from L cells, but they are distinct: glicentin is the larger proglucagon 1–69 fragment (containing OXM at its C-terminal end plus a 32-residue N-terminal "GRPP" extension), while OXM is the 37-residue bioactive product. Glicentin has minimal GCGR or GLP-1R agonist activity. Older "enteroglucagon" immunoassays detect both, which is a persistent source of confusion in the historical literature (Lafferty et al. 2021).
- "The anorectic effect of OXM is glucagon-receptor-mediated." It is not. The food-intake reduction is GLP-1R-mediated: GLP-1R antagonism abolishes it, and GLP-1 receptor knockout mice do not respond. GCGR activation by OXM primarily drives the energy-expenditure component, not the satiety component (Dakin et al. 2001; Scott et al. 2018).
- "Cotadutide, survodutide and mazdutide are just oxyntomodulin with a longer name." They are engineered peptide analogs that borrow OXM's dual-receptor pharmacology but differ substantially in sequence, acylation, half-life and receptor balance. Native OXM has a minutes-scale half-life and requires thrice-daily injection; cotadutide is once-daily; survodutide and mazdutide are once-weekly. The chemistry is what makes chronic dosing practical (Lafferty et al. 2021).
Common questions
How does OXM differ from approved GLP-1R agonists like semaglutide? Approved GLP-1R agonists (semaglutide, liraglutide, dulaglutide) are selective for GLP-1R. OXM activates both GLP-1R and GCGR — adding the glucagon-receptor-mediated energy-expenditure component that the selective agonists do not produce. The engineered dual agonists (cotadutide, survodutide, mazdutide) and the triple agonist retatrutide (GLP-1R/GCGR/GIPR) are the clinical-grade descendants of OXM's natural dual pharmacology, designed for higher potency and much longer half-life than native OXM.
Why isn't OXM itself a drug? Three reasons: it has low intrinsic receptor potency (roughly 10–100× weaker than the selective endogenous agonists), it is degraded rapidly by DPP-4 and neutral endopeptidase, and its circulating half-life is on the order of minutes. Chronic dosing in humans would require multiple injections per day — which is what the original Wynne et al. 2005 protocol used. The engineered analogs solve all three problems and are practical for once-daily or once-weekly dosing.
How does OXM relate to GLP-1 and GLP-2? All three are cleaved from the same proglucagon precursor by L cells of the distal small intestine and colon, and all three are co-secreted postprandially. GLP-1 is the primary incretin and satiety signal (acts at GLP-1R); GLP-2 is the intestinotrophic hormone (acts at GLP-2R, with an approved drug analog teduglutide for short bowel syndrome); OXM is the dual-acting member that signals at both GLP-1R and GCGR.
Known effects
- Appetite suppression / reduced food intake — Human RCT evidence (Wynne et al., Diabetes 2005); GLP-1R-mediated
- Short-term weight loss — Human RCT, 2.3 kg over 4 weeks (Wynne et al. 2005)
- Increased energy expenditure — Human crossover RCT (Wynne et al., International Journal of Obesity 2006); GCGR-mediated
- Glucoregulatory effects independent of weight loss — Human infusion RCT in obesity ± T2D (Shankar et al., Diabetes 2018)
- Gastric acid inhibition (the historically eponymous activity) — preclinical and mechanistic
- Physiological template for the dual-agonist drug class — proof-of-concept now extended into Phase 3 by cotadutide, survodutide, mazdutide and retatrutide
Safety signals
Native OXM has been administered to humans only in short trials (days to a few weeks) at modest sample sizes; there is no long-term safety dataset for native OXM specifically. Reported adverse events in those trials have been mild — predominantly transient nausea, injection-site discomfort, and small transient increases in heart rate (Wynne et al. 2005; Shankar et al. 2018). Class-level safety considerations for sustained dual GLP-1R/GCGR agonism are being characterised through the dedicated programs for the engineered analogs (cotadutide, survodutide), not through native OXM. The chronic-exposure safety profile of native OXM is therefore unknown.
Regulatory status
- US: Native oxyntomodulin is not FDA-approved for any indication and is not a prescribable drug. It is used in research settings only.
- EU / other: No approval by the EMA or any other major regulator for native OXM.
- Engineered analogs derived from OXM's pharmacology: mazdutide is approved in China; survodutide and cotadutide are investigational (survodutide in Phase 3); retatrutide (a GLP-1R/GCGR/GIPR triple agonist) is in Phase 3. These are separate molecules with their own regulatory trajectories.
- WADA: As a peptide hormone, native OXM falls under S2 (peptide hormones, growth factors, related substances and mimetics) and would be prohibited at all times; because it is unapproved by any government health authority, S0 (non-approved substances) also applies.
Related peptides
- Glucagon — the 29-residue parent of OXM; pure GCGR agonist; FDA-approved for emergency treatment of severe hypoglycemia.
- GLP-1 / GLP-1(7-36)-amide — the other principal proglucagon-derived peptide; selective GLP-1R agonist; basis for semaglutide, liraglutide and the rest of the approved incretin drug class.
- GLP-2 — third proglucagon-derived peptide; GLP-2R agonist; basis for teduglutide (short bowel syndrome).
- Glicentin — the larger 69-residue intestinal proglucagon product that contains OXM at its C-terminal end; minimal receptor activity in its own right.
- Cotadutide (MEDI0382), survodutide (BI 456906), mazdutide — engineered long-acting GLP-1R/GCGR dual agonists derived directly from OXM's pharmacological template.
- Retatrutide (LY3437943) — a GLP-1R/GCGR/GIPR triple agonist that extends the dual-agonist concept by adding GIP receptor activity.
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.
Could the unique tail on this natural gut hormone change how it signals inside cells compared to GLP-1 and glucagon?
If true, drug developers could use this tail as a tuning knob to make safer, longer-acting weight-loss drugs with fewer side effects from receptor shutdown.
Could the small tail on this hormone tip the scales toward feeling full versus burning more calories?
If true, doctors might one day match a patient's weight-loss drug to their personal biology by tuning this tail, rather than using one-size-fits-all injections.
Might this gut hormone's weaker effect on its receptors actually be better for patients than maximum-strength drugs?
If true, future drugs could be designed to be gentler rather than stronger, potentially reducing nausea and blood sugar swings for millions of people with obesity or diabetes.
Might this natural gut hormone help slow Alzheimer's or Parkinson's disease by calming brain inflammation?
If true, people with neurodegenerative diseases could gain a new treatment option from a hormone already present in the human body, possibly with fewer side effects than current experimental drugs.
Could changing just two amino acids at the end of this hormone make it last hours instead of minutes?
If true, a minimally modified version of this natural hormone could become a practical, longer-acting weight-loss drug with fewer synthetic modifications than current alternatives.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.9403464198112488 | boltz-2 |
| ranking score | 0.8143402934074402 | boltz-2 |
▸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 | colabfold_nvidia |
| diffusion samples | 1 |
| runtime | — |
| predicted by | mlx@peptide |
| predicted at | 2026-04-25 |
▸citationbibtex
@peptide{pep10600,
sequence = {HSQGTFTSDYSKYLDSRRAQDFVQWLMNTKRNRNNIA},
target = {gcgr},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}