This is the most comprehensive peptide reference guide for performance athletes, bodybuilders, and enhanced lifters available today. Designed to educate, clarify, and empower, this resource covers everything from peptide classes and mechanisms to protocols, safety, and advanced stacking strategies. Bookmark this — it’s the FitScience peptide bible.
📖 Table of Contents
🔬 What Are Peptides?
Peptides are short chains of amino acids that act as messengers in the body. They regulate processes like tissue repair, hormone release, fat breakdown, cognition, and more. Unlike anabolic steroids, peptides offer targeted signaling with far fewer systemic risks.
🧠 How Peptides Work: GH Axis, Receptors, and Beyond
Peptides often bind to specific receptors — like GHRH, GHRP, melanocortin, or kisspeptin receptors — to initiate biological cascades.
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GHRH peptides (e.g., CJC-1295) trigger the release of growth hormone via pituitary stimulation.
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GHRP peptides (e.g., Ipamorelin) stimulate GH by blocking somatostatin (GH inhibitor).
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IGF peptides (e.g., IGF-1 LR3) directly stimulate muscle growth, repair, and glucose uptake.
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Mitochondrial peptides like MOTS-c improve endurance, insulin sensitivity, and energy metabolism.
This specificity allows for stacking without compounding side effects — when done right.
📚 Peptide Classifications
| Category | Example Peptides | Primary Use |
|---|---|---|
| GH Secretagogues | MK-677, CJC-1295, Ipamorelin | GH release, recovery, fat loss |
| Healing Peptides | BPC-157, TB-500, GHK-Cu | Soft tissue & wound repair |
| IGF Axis Peptides | IGF-1 LR3, PEG-MGF | Muscle growth, nutrient uptake |
| Neuro Peptides | Selank, Semax, Cerebrolysin | Mood, cognition, neuroprotection |
| Mitochondrial Peptides | Humanin, MOTS-c | Metabolic health, endurance |
| Anti-Aging/Aesthetic | Epitalon, GHK-Cu, Thymosin Alpha | Longevity, collagen, sleep |
| Sexual Function | PT-141, Kisspeptin-10 | Libido, arousal |
🧬 Full Peptide Database
| Peptide | Primary Use | Typical Dose | Half-Life | Suppression Risk |
|---|---|---|---|---|
| BPC-157 | Tendon/Gut Healing | 250–500 mcg/day | 4–6h | None |
| TB-500 | Soft Tissue Repair | 2–5 mg/week | 6–8h | None |
| CJC-1295 DAC | Long GH Release | 2 mg/week | 5–8 days | None |
| CJC-1295 no DAC | Short GH Pulse | 100–200 mcg/day | 30 min | None |
| Ipamorelin | GH Pulse + Sleep | 200–300 mcg/day | 2–3h | None |
| MK-677 | Oral GH Boost | 10–25 mg/day | 24h | None |
| IGF-1 LR3 | Muscle Growth | 20–40 mcg/day | ~20h | Mild |
| PEG-MGF | Muscle Repair | 200 mcg 2x/week | 2–3h | None |
| GHRP-2 | GH Release | 100–300 mcg/day | 15–60 min | Mild |
| GHRP-6 | GH Release + Appetite | 100–300 mcg/day | 30–60 min | Mild |
| Hexarelin | GH Pulse | 100 mcg/day | 60–90 min | Moderate |
| Fragment 176-191 | Fat Loss | 250–500 mcg/day | 2–3h | None |
| AOD-9604 | Fat Loss | 500 mcg/day | Short | None |
| Tesamorelin | Visceral Fat Loss | 1–2 mg/day | 1–2h | None |
| Thymosin Beta-4 | Soft Tissue Regeneration | 2–5 mg/week | ~6h | None |
| Thymosin Alpha-1 | Immune Support | 1.6 mg 2x/week | ~2h | None |
| GHK-Cu | Skin/Collagen Repair | 100–200 mcg/day | Short | None |
| Epitalon | Anti-aging | 5–10 mg/day | Short | None |
| MOTS-c | Mitochondrial Support | 5–10 mg/day | 6h | None |
| Humanin | Longevity | 2–5 mg/day | Short | None |
| Selank | Mood/Cognition | 250–500 mcg/day | Short | None |
| Semax | Cognitive Enhancement | 200–500 mcg/day | Short | None |
| DSIP | Sleep Support | 100 mcg before bed | Short | None |
| Cerebrolysin | Neuroprotection | 5 mL/day IM | Short | None |
| PT-141 | Sexual Arousal | 1.75 mg as needed | 2–4h | None |
| Kisspeptin-10 | LH/FSH Stimulator | 100 mcg 2–3x/week | Short | None |
| Oxytocin | Bonding/Libido | 10 IU as needed | Short | None |
| Tymosin-α1 | Immune Modulation | 1.6 mg/week | ~2h | None |
| Follistatin 344 | Muscle Growth | 100–200 mcg/day | Unknown | Unknown |
| GDF-8 Inhibitor | Myostatin Block | 50–100 mcg | Unknown | High |
| Melanotan II | Tanning/Libido | 500–1000 mcg | 1–2h | None |
| ACTH | Adrenal Stimulator | 10–20 IU | Short | Moderate |
| LR3 IGF-1 DES | Localized Growth | 20–40 mcg/day | ~1h | Mild |
| P21 | Cognitive Repair | 200 mcg/day | Short | None |
| 9-Methyl-β-carboline | Neuroregeneration | 0.5–1 mg/day | Unknown | None |
| Acetyl Hexapeptide-8 | Wrinkle Reduction | Topical | Short | None |
| Argireline | Anti-Wrinkle | Topical | Short | None |
| Snap-8 | Botox Alternative | Topical | Short | None |
| Bremelanotide | Sexual Stimulant | 1.25–1.75 mg | 2–3h | None |
| HGH Fragment | Fat Mobilization | 250–500 mcg/day | 2–3h | None |
| IGF-1 Ec (MGF) | Muscle Growth | 100–200 mcg/day | Short | Mild |
| ALCAR Peptide | Cognitive Support | 100 mg/day | Short | None |
| VIP | Pulmonary Health | 100 mcg | Short | None |
| B7-33 | Anti-fibrosis | 100 mcg/day | Short | None |
| NKCP Peptide | Cardiovascular Support | 100–200 mg/day | Short | None |
| GLP-1 Agonist | Appetite Control | 0.25–1 mg/week | Long | None |
| Exendin-4 | Insulin Sensitivity | 10 mcg BID | Short | None |
| Irisin Peptide | Thermogenesis | Unknown | Unknown | Unknown |
| 5-Amino-1MQ | NAD+ Metabolism | 50–100 mg/day | Unknown | None |
🏗 Goal-Based Peptide Stacks
Mass Building Stack
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MK-677 (25 mg/day, AM)
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IGF-1 LR3 (40 mcg post workout, IM)
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CJC-1295 DAC (2 mg/week)
Fat Loss Stack
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Fragment 176-191 (250 mcg AM & PM)
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Tesamorelin (1 mg before bed)
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Ipamorelin (200 mcg at night)
Injury Recovery Stack
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BPC-157 (250 mcg AM/PM)
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TB-500 (2.5 mg/week)
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GHK-Cu (100 mcg/day)
Longevity / Anti-Aging Stack
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Epitalon (10 mg before bed)
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MOTS-c (10 mg/day, M–F)
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GHK-Cu (topical + injectable)
🧬 Protocol Design & Scheduling
| Protocol Type | Duration | Notes |
|---|---|---|
| GH Peptides (e.g., CJC/IPAM) | 8–12 weeks | Best used 5-on, 2-off to prevent desensitization |
| Healing Peptides | 4–6 weeks | Discontinue after full recovery |
| IGF-1 LR3 | 3–4 weeks | Max 30 days to avoid downregulation |
| MK-677 | 3–6 months | No cycling needed; assess glucose |
💉 Delivery Methods
| Method | Peptides Used | Notes |
|---|---|---|
| Subcutaneous | BPC-157, CJC-1295, Fragment | Most peptides are SubQ-friendly |
| Intramuscular | IGF-1, PEG-MGF | Localized growth targeting |
| Nasal Spray | Selank, Semax, PT-141 | Useful for mood or libido stacks |
| Oral | MK-677, MOTS-c | High bioavailability analogs only |
⚠️ Peptide Safety, Legality & Monitoring
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Use only BAC water for reconstitution
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Track IGF-1, glucose, HCT when using GH analogs or MK-677
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Most peptides are not FDA-approved for human use, but are legal to purchase for research
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Buy from lab-tested, verified sources only
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Store peptides in the refrigerator after mixing
❓ Frequently Asked Questions
Do peptides require PCT?
Generally no. However, long GH exposure or IGF-1 may benefit from off-cycling.
Are peptides legal?
Yes, they are unscheduled in the U.S., but only allowed for “research purposes.” Import with caution.
What’s the best peptide for fat loss?
Fragment 176-191 + Tesamorelin = excellent combo.
Can peptides be used with SARMs?
Yes, peptide + SARM stacks are popular: MK-677 + RAD-140 or LGD-4033, for example.
