Bimagrumab_Dosage, benefits & legal status
Also known as BYM338
An experimental shot that strips fat while adding muscle.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Bimagrumab?
Plain language first. The technical label stays, but it never stands alone.Overview
By releasing that brake it builds muscle while the body sheds fat, an unusual combination being studied with GLP-1 drugs. It is still experimental.
Bimagrumab is a monoclonal antibody that blocks the activin type II receptor, a signal that normally limits muscle.
What it's used for
An unusual experimental shot that strips fat while adding muscle, by blocking a signal that limits muscle. It is being studied alongside GLP-1 drugs.
How does Bimagrumab work?
What it does in the body, and where.Bimagrumab is not a weight-loss drug in the usual sense. It changes what you lose rather than how much.
- 01It blocks the activin type II receptorThat receptor carries the signal that normally limits how much muscle you build. Blocking it releases the brake.
- 02Muscle grows while fat is lostAn unusual combination. Most weight loss, including from GLP-1 drugs, takes muscle along with fat.
- 03It is being tested alongside GLP-1 drugs, not instead of themThe interest is in pairing it with semaglutide so the weight lost is fat rather than lean tissue.
- 04Dosed by body weight, into a vein10 to 30 mg per kilogram by infusion, which is a very different proposition from a weekly self-injection.
- 05InvestigationalPhase 2 only.
Where this compound is thought to act.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
- Losing fat while gaining muscle, an unusual combination being studied alongside the GLP-1 drugsInvestigational
- Muscle-wasting conditions, where an earlier trial failed to show functional benefitInvestigational
The published record
94
Records indexed for Bimagrumab
72 in humans, 31 of them original studies.
17 registered trials, 10 with posted results.
Counted from Europe PMC indexing, not read by a person. Human means indexed under humans, which includes reviews and work on human cells. Original studies exclude reviews and lab work on human cells.Last updated 11 September 2026.
At a glance
Four things to know about Bimagrumab
Evidence
Investigational
Category
Muscle building
Common vial
Varies
Half-life
5 to 19 days, depending on concentration
How much, and do you cycle it?
The range, and whether you take breaks.10 up to 30 mg/kg per month (trial doses), monthly. Not cycled. Infused every 12 weeks in the trialsTrial dose
The dosing interval is long because the antibody lasts a long time, not because anyone is cycling it. The phase 2b trial ran 48 weeks blinded with a further 24 weeks open label.
How long does it stay in the body?
The half-life, and where the figure comes from.5 to 19 days, depending on concentrationTrial protocol
The half-life is not fixed. It runs about 19 days when blood levels are high and falls to about 5 days when clearance is at its fastest, because the antibody is consumed by the target it binds.
Source: Petricoul O, et al. Clin Pharmacokinet 2023;62:141-155, DOI 10.1007/s40262-022-01189-0
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Bimagrumab is dosed by body weight: 10 to 30 mg/kg per month.
Only mg/kg dose in the library. The calculator has no body-weight input, so it cannot produce a draw for this compound.
Dosed by body weight, into a vein, not as a flat amount. Phase 2 used 10 or 30 mg per kg.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Bimagrumab keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.This compound is in clinical trials and is not sold in a standard vial, so there is no common vial size to show. Trial doses are given as prepared by the study, and the reconstitution calculator does not apply. Dosed by body weight and given by infusion in trials, so no vial size applies.
Who should avoid it
- No formal contraindications established
- Pregnancy
Stop and get help
- Severe upper stomach pain, which can signal pancreas inflammation
- Signs of an allergic reaction such as face or throat swelling, hives, or trouble breathing
Common effects
- Muscle spasms, in roughly half to two thirds of people at higher doses
- Diarrhea in about four in ten
- Acne or skin eruptions
- Falls, in older trial participants
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Bimagrumab approved?
And where the numbers on this page come from.No. Bimagrumab is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteInto a vein or under the skin
- CheckedSeptember 2026
What has happened recently
We have not yet written a full regulatory note for this compound. The status above is current as of the date shown.
You can compare this against the whole library, or read how to check a seller.
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
- Reviewed8 September 2026
What else is like Bimagrumab?
Others in Muscle building, side by side.If you're weighing Bimagrumab, it's worth reading Ipamorelin + CJC-1295 (no DAC) blend, IGF-1 LR3, and IGF-1 DES in the same class.
An experimental shot that strips fat while adding muscle.
- Dose
- 10 up to 30 mg/kg per month (trial doses)
- How often
- Monthly
The popular growth-hormone combo in one shot, for muscle, recovery, and sleep.
- Dose
- ~0.1 mg CJC-1295 per dose (the ipamorelin follows your ratio)
- How often
- Daily, often at night
A powerful muscle-builder that also drops blood sugar hard.
- Dose
- 0.02 up to 0.05 mg per day (start low, increase slowly)
- How often
- Daily, cycled
A short-acting muscle-builder that works right where you inject it.
- Dose
- 0.05 up to 0.15 mg per dose (start low, increase slowly)
- How often
- Around training
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- Why Does My Peptide Injection Itch or Welt
Injection-site irritation, a histamine reaction, or a true allergy, and how to tell them apart.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
Sources
- Heymsfield et al., effect of bimagrumab vs placebo on body fat mass in type 2 diabetes, JAMA Network Open(2021)Phase 2, 75 patients over 48 weeks. Fat mass fell and lean mass rose against placebo. Only 58 of 75, 77.3 percent, completed. Eight adverse events led to discontinuation in the bimagrumab group and none in placebo.
- BELIEVE, bimagrumab plus semaglutide alone or in combination for obesity, a randomized phase 2 trial, Nature Medicine(2026)Combination reached up to 17.8 kg weight reduction against up to 14.2 kg for semaglutide alone, and preserved lean mass where semaglutide alone reduced it. The reason this compound is discussed at all is muscle preservation, not weight loss.
Last reviewed 8 September 2026
Beyond these, 94 records are indexed. Browse the records