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Research Cluster
Performance & Body Composition Peptides
Performance peptides are used—mostly illicitly—for muscle growth, body composition, and athletic performance. All four compounds are WADA-prohibited, and none have FDA approval for performance or body composition indications.
The evidence base here is almost entirely preclinical. These compounds are widely discussed in bodybuilding and performance communities, but the gap between their biological plausibility and their human evidence is vast.
Cluster at a Glance
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4 Compounds Covered |
3 Preclinical Only |
1 It’s Complicated |
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Preclinical Only Animal models and cell culture only |
It’s Complicated Mixed evidence or classification issues |
BLUF: Bottom Line Up Front
No FDA-approved compounds. No completed Phase III trials. All four are WADA-prohibited. MGF/PEG-MGF, IGF-1 DES, and IGF-1 LR3 are insulin-like growth factor variants with different half-lives and tissue selectivity—all have preclinical data on muscle hypertrophy but effectively no controlled human evidence for performance or body composition. Follistatin’s evidence picture is complicated: it has real clinical research on myostatin inhibition but the therapeutic development has moved to gene therapy and monoclonal antibodies (anti-myostatin), not peptide administration. This cluster has the worst evidence-to-enthusiasm ratio on the site.
In This Article
Compounds in This Cluster
All 4 compounds in the Performance & Body Composition Peptides cluster, organized by mechanism and editorial function. Each grouping reflects how these compounds relate to each other scientifically—not just alphabetically.
Group 1 of 2
The IGF-1 Variants
Modified forms of insulin-like growth factor-1 with different pharmacokinetic profiles, all targeting muscle anabolism.
Group 2 of 2
The Myostatin Pathway
A protein that regulates muscle growth by inhibiting myostatin, the body's muscle growth brake.
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How These Compounds Relate
All four compounds in this cluster converge on muscle anabolism through the IGF-1/mTOR signaling axis, but they arrive there through different routes. The three IGF-1 variants (MGF, IGF-1 DES, IGF-1 LR3) are all modified forms of the same parent molecule—insulin-like growth factor-1. Their differences are pharmacokinetic: MGF is the splice variant produced naturally by exercised muscle, IGF-1 DES has enhanced receptor binding, and IGF-1 LR3 has extended duration of action. In practice, bodybuilders choose between them based on desired timing and localization of the anabolic signal.
Follistatin works upstream of the IGF-1 system by neutralizing myostatin—the protein that actively limits muscle growth. The biology is dramatic: myostatin-knockout animals develop extraordinary muscle mass. But translating this to human therapy has proven difficult. Gene therapy approaches (AAV-follistatin) have shown measurable muscle effects in clinical trials for muscular dystrophies, but injectable follistatin peptide has not demonstrated equivalent results.
The fundamental problem with this entire cluster is the gap between mechanism and evidence. The IGF-1 pathway is unquestionably involved in muscle hypertrophy. Myostatin inhibition unquestionably increases muscle mass in animals. But none of these specific compounds have controlled human data showing that injecting them produces meaningful body composition changes beyond what training and nutrition achieve alone.
| Shared Mechanism | Compounds |
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IGF-1 Receptor Agonism Activates the IGF-1R/PI3K/Akt/mTOR signaling cascade to promote muscle protein synthesis and satellite cell proliferation. |
MGF / PEG-MGF, IGF-1 DES, IGF-1 LR3 |
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Myostatin Antagonism Binds and neutralizes myostatin and activin, removing the TGF-β-mediated brake on skeletal muscle growth. |
Follistatin |
Plain English
This is the cluster the bodybuilding community talks about most—and the one with the least human evidence. Three peptides (MGF, IGF-1 DES, IGF-1 LR3) are modified versions of the same growth factor, tweaked for different durations and tissue targeting. One (Follistatin) blocks your body’s natural muscle growth limiter. The biology is real: these pathways genuinely control muscle growth. But ‘the pathway works’ is not the same as ‘injecting this peptide builds muscle in humans.’ None of these compounds have controlled human trials showing body composition changes. All are banned by WADA.
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Disclaimer: This page is for educational and research purposes only. It does not constitute medical advice, diagnosis, or treatment. The compounds discussed are subjects of ongoing scientific research and have not been evaluated by the FDA for all applications described. Consult a qualified healthcare provider before making any decisions about your health.