Page last checked 2026-09-07

Goal

Peptides for muscle growth

These six peptides have not established a muscle-building benefit. Most studies measured hormones; one hexarelin study measured lean mass and found no significant change.

Source for this answer

Source: Based on 6 compound guides · checked 2026-09-07

Four compounds have human hormone studies. IGF-1 LR3 and PEG-MGF have no human dosing study in the records used here.

Muscle size, strength and recovery need their own measurements. A rise in growth hormone does not by itself show that a person gains muscle.

At a glance

Compounds covered

FDA-approved for this goal

Being tested for this goal

Reported use only

Start with the outcome

What result do you mean by muscle growth?

Bigger muscles, more strength, faster recovery and better athletic performance are different outcomes. Choose the one you want to understand before comparing the studies.

No established muscle-building benefit

Bigger muscles

Four compounds changed or tested growth hormone in people. A 16-week hexarelin study measured lean mass and found no significant change. The other cited studies do not show muscle gain.

No human performance outcome

More strength or athletic performance

The studies cited here do not show improvements in strength, power, endurance or athletic performance. A hormone reading cannot fill in those outcomes.

A different evidence question

Recovery after training or injury

The ipamorelin trials studied bowel function after surgery, not workout recovery. Injury and tissue-healing studies are covered on the recovery page.

Compare the recovery evidence

No direct comparison in these sources

Safer than anabolic steroids

No study in these sources compares any of the six with an anabolic steroid. Sparse or missing data cannot show a safer alternative.

Six compounds, and what each study actually measured

Compare the outcome each study measured. Hormone changes, body composition and strength answer different questions.

◆ 6 compounds coveredsources shown in each row

Compounds people take for this purpose, why they use them, what human research has measured, and where the evidence comes from.
Compound	What people take it for	What research shows	Evidence
Ipamorelin	Offered for muscle gain because it stimulates growth-hormone release.Measured in a human study	Human studies measured hormone release and bowel function after surgery. The two completed bowel-surgery trials did not beat placebo on their main outcome. Those outcomes do not show muscle growth.	Human trialDose from a human trial · no FDA label
CJC-1295	Sold for muscle growth, often paired with ipamorelin.Measured in a human study	The cited human studies measured growth hormone and IGF-I. One found no significant difference between responses to 60 and 90 mcg/kg. The studies used the long-acting form with a drug-affinity complex, not the form sold as no-DAC.	limited human dataDose from a human trial · no FDA label
Hexarelin	Sold for muscle growth and recovery because it stimulates growth-hormone release.Measured in a human study	A 16-week study measured lean body mass and found no significant change from baseline. Its growth-hormone response fell from 19.1 to 10.5 mcg/L·h and recovered after stopping. A separate short study raised growth hormone without changing IGF-I.	limited human dataDose from a human trial · no FDA label
Sermorelin	Offered by wellness clinics for changes in body composition.Measured in a human study	Its largest trial ran in 110 children with growth-hormone deficiency, where height velocity rose from 4.1 to 8.0 cm/yr at six months. The one adult study ran 14 days in men of about 68, and only the 1 mg arm raised growth hormone above their own baseline.	limited human dataDose from a human trial · no FDA label
IGF-1 LR3	Discussed for muscle growth in bodybuilding use.Reported use only	The sources here describe a reagent used to grow cells, along with animal research. They do not include a human dosing study or establish a muscle-building benefit in people.	no human dose shown to workDose reported in the literature only
PEG-MGF	Sold for muscle repair and growth after training.Reported use only	The cited human research measured growth-factor signals in muscle samples; participants were not given PEG-MGF. Experiments giving the peptide used cells or animals. Those results do not show a human muscle-building dose.	no human dose shown to workDose reported in the literature only

4 rest on a human study that measured something in this goal. 2 rest on reported use alone, with no study behind them.

A hormone rise does not show muscle growth

CJC-1295 studies measured increases in both growth hormone and IGF-I. Hexarelin studies also measured these hormones, with different results. A hormone reading alone cannot tell how much muscle someone gained.

The 16-week hexarelin study did assess body composition. It found no significant change in lean body mass, total body fat or bone density compared with baseline. That is a measured result, not an absence of measurement.

The growth-hormone response weakened during repeated hexarelin dosing and recovered four weeks after treatment stopped. These findings do not show a muscle-building schedule.

What would establish a muscle-building benefit?

A useful trial would compare changes in muscle or lean mass between groups while accounting for diet and training. Strength and physical function would need separate measurements.

The available sources do not show that these six compounds improve muscle growth. Cell and animal results for IGF-1 LR3 and PEG-MGF cannot supply a human treatment dose.

Where to go next

The 10 goal categories, side by side

Nothing here ranks anything: a reason to prefer one compound is a reason to sell it.

What PEG-MGF is, how it is used, and what has been studied

PEG-MGF is a pegylated igf-1 splice-variant peptide (research compound).

How hexarelin differs from the rest of its class

No published human dosing schedule was found for hexarelin.

How IGF-1 LR3 differs from the rest of its class

No published human dosing schedule was found for IGF-1 LR3.

Testosterone: the page beside the pitch

The kisspeptin study was a hormone experiment.

Which skin claims have a trial

No established dose for a skin-care injection — see which popular claims still have no human evidence.

How ipamorelin differs from the rest of its class

No published human dosing schedule was found for ipamorelin.

How CJC-1295 differs from the rest of its class

No published human dosing schedule was found for CJC-1295.

Every purpose covered this way is listed on the index of goals people buy peptides for.

Questions readers ask

Which peptides are best for muscle growth?

These studies do not show a best option for muscle gain. A 16-week hexarelin study measured lean mass and found no significant change. Most other studies measured hormones.

Are peptides safer than steroids?

The studies cited here do not compare these peptides with anabolic steroids. Missing safety data cannot establish that one is safer.

What are the downsides of taking peptides?

Risks depend on the compound and preparation. These six records leave important questions about muscle-building benefits and long-term safety unanswered. Hormone effects do not establish a safe regimen.

Do peptides really work for muscle building?

These studies do not establish a muscle-building benefit. Growth-hormone readings changed in some studies, while the 16-week hexarelin study found no significant change in lean mass.

11primary sources, each with the day we read it — open the documents used on this page