A peptide is a short chain of between two and fifty amino acids linked by peptide bonds.[3] In contemporary sports and fitness culture, the term has acquired a secondary meaning as a shorthand for a class of synthetic and semi-synthetic compounds used to modulate growth, body composition, appetite, and tissue repair. The question of whether their use is compatible with natural bodybuilding — whether a peptide user is, in the vernacular, "natty" — is the subject of ongoing dispute among federations and athletes.[2]
This article catalogues 22 compounds frequently encountered in the peptide marketplace, the function each is researched for, and the verdict of the present rulebook.
List of peptides
The following table lists each entry with its function and current classification under WADA and the federations consulted.
| Current popularity⇵ | Compound⇵ | Function⇵ | Verdict⇵ |
|---|---|---|---|
| #1 | NAD+ | Boosts cellular energy production and DNA repair. Activates longevity enzymes. Improves metabolism and mitochondrial health. Cellular benefits proven, human longevity unproven. | Natty |
| #2 | Retatrutide | Triple agonist that curbs appetite and raises energy expenditure for 24% weight loss. Improves blood sugar, lowers blood pressure, and normalizes liver fat. Investigational; not FDA-approved. | Not natty |
| #3 | Tirzepatide | Dual GIP/GLP-1 agonist. Reduces appetite for up to 21% weight loss. Improves blood sugar and diabetes control. First drug approved for obstructive sleep apnea. GI side effects common. | Natty |
| #4 | Ozempic | Reduces appetite and slows digestion for 15-21% weight loss. Improves blood sugar control. Lowers heart attack and stroke risk by 20%. | Natty |
| #5 | Glutathione | The body's master intracellular antioxidant. Scavenges free radicals and supports liver phase-II detoxification. Regenerates vitamins C and E. Used for liver health, skin brightening, and anti-aging. | Natty |
| #6 | MOTS-c | Mitochondrial-derived peptide that activates AMPK to improve insulin sensitivity and reproduce exercise-like metabolic adaptations in preclinical models. Investigational and WADA-banned; no approved human use. | Not natty |
| #7 | Tesamorelin | Stimulates growth hormone release, lowering visceral abdominal fat and triglycerides. FDA-approved for HIV-associated lipodystrophy. Daily subcutaneous injection; fat reaccumulates when stopped. | Not natty |
| #8 | BPC-157 | Speeds healing of tendons, ligaments, muscles, and gut lining. Promotes new blood vessel growth and reduces inflammation. Evidence is almost entirely from animal studies. | Not natty |
| #9 | Ipamorelin | Selectively triggers growth hormone release without raising cortisol or prolactin. Human efficacy unproven: a Phase 2 trial failed and body-composition benefits remain preclinical. Subcutaneous injection. | Not natty |
| #10 | Semax | Synthetic ACTH(4-10) analogue used in Russia as a nootropic and neuroprotectant. Reported to raise BDNF without corticosteroid effects. Evidence is mostly preclinical; no FDA or EMA approval. | Not natty |
| #11 | CJC-1295 | Raises growth hormone 2-10 fold and IGF-1 for over a week per injection. Weekly subcutaneous dosing. Investigational only; cardiovascular risks and product-quality concerns. | Not natty |
| #12 | TB-500 | Speeds wound healing, muscle and tendon recovery. Reduces inflammation, improves joint mobility, minimizes scar tissue formation. | Not natty |
| #13 | Copper peptide GHK-Cu | Copper-binding tripeptide that supports skin regeneration, collagen synthesis, wound healing, and hair growth, with antioxidant and anti-inflammatory activity. Used topically in cosmetics; deeper effects remain investigational. | Not natty |
| #14 | Selank | Synthetic tuftsin analogue used as an anxiolytic nootropic. Reported to act on GABA and monoamine signalling without sedation or dependence. Registered as a medicine in Russia only. | Not natty |
| #15 | Melanotan II | Stimulates melanin production to darken skin and facilitate tanning. May also increase sexual arousal and reduce appetite. Unapproved for human use; linked to nausea and mole changes. | Not natty |
| #16 | Epithalon | Marketed as an anti-aging peptide. In preclinical studies it boosts telomerase activity, supports the body's own melatonin production, and shows antioxidant effects. Human evidence is minimal. | Not natty |
| #17 | MK-677 | Oral ghrelin receptor agonist that raises growth hormone and IGF-1. Increases lean mass, bone density, and deep sleep. Causes insulin resistance and elevated blood sugar. | Not natty |
| #18 | 5-Amino-1MQ | Oral small-molecule NNMT inhibitor that raises NAD+ and S-adenosyl methionine to boost fat-cell energy expenditure. Studied only in rodents for fat loss; no human trials exist. | Not natty |
| #19 | IGF-1 LR3 | Long-acting IGF-1 analog studied preclinically for muscle growth and tissue repair. No peer-reviewed human evidence of benefit. Risks include hypoglycemia, joint pain, unproven cancer concerns. | Not natty |
| #20 | Delta-sleep-inducing peptide | A neuropeptide named for inducing delta EEG sleep activity in animals, though its own link to human sleep is weak and poorly characterized. Shows preclinical antiepileptic activity. | Not natty |
| #21 | Afamelanotide | Raises skin melanin by activating MC1 receptors. Approved to prevent phototoxic pain in erythropoietic protoporphyria, a rare genetic light sensitivity. Given as a subcutaneous implant. | Natty |
| #22 | Bremelanotide | FDA-approved (as Vyleesi) for low sexual desire in premenopausal women. Activates central melanocortin receptors to drive arousal. Shows preclinical promise for erectile dysfunction. Given by subcutaneous injection. | Natty |
Peptide stacks
A stack is a fixed combination of two or more peptides sold in a single vial, so one reconstitution covers every compound in it. The combinations below pair repair and remodeling compounds and are the ones encountered most often in the research marketplace. A stack inherits the strictest verdict among its components: one compound marked "not natty" marks the whole vial. Vendor names link to affiliate listings.
| Stack⇵ | Contains⇵ | Function⇵ | Verdict⇵ |
|---|---|---|---|
| Wolverine | BPC-157 + TB-500 | BPC-157 and TB-500 in one vial. Studied for angiogenesis, endothelial repair, and actin cytoskeletal remodeling in musculoskeletal recovery research. | Not natty |
| GLOW | Copper peptide GHK-Cu + BPC-157 + TB-500 | Adds GHK-Cu to the Wolverine pair. Studied for extracellular matrix remodeling and angiogenesis signaling. Common in dermal repair research. | Not natty |
| KLOW | KPV + Copper peptide GHK-Cu + BPC-157 + TB-500 | GLOW plus KPV. Studied for tissue repair signaling, inflammatory cytokine regulation, and extracellular matrix remodeling. | Not natty |
Natty status
The classification "natty" or "not natty" is not a statement about legality, but about compatibility with the rules of natural sport federations and the spirit of the WADA Code.[1]
Criteria
An entry is marked "not natty" when any of the following is true:
- The compound appears on the WADA prohibited list.[1]
- A major natural bodybuilding federation explicitly bans the substance.[2]
- The compound provides a performance advantage beyond what is achievable through diet, training, and recovery alone.
Gray areas
Therapeutic use of BPC-157 for tendon repair, or of semaglutide as a prescribed diabetes drug, occupies a contested middle ground. Practice varies by federation.[2]
Frequently asked questions
- What does 'natty' mean?
- Short for 'natural.' In fitness it refers to results achieved without anabolic steroids, growth hormone, or other prohibited performance-enhancing substances.
- Are peptides considered natty?
- Most performance-enhancing peptides are not. Therapeutic uses fall into a contested gray area.
- How is a peptide's status determined?
- By reference to WADA's prohibited list, natural bodybuilding federation rulebooks, and the intent of use.
- What is the difference between natty and enhanced?
- Natty denotes reliance on natural methods and legal staples; enhanced denotes anything reaching past the natural ceiling.
- Can peptides be used medically and remain natty?
- Therapeutic use for genuine injury is treated leniently by some federations and strictly by others.
See also
- Anabolic steroid
- Growth hormone
- Insulin-like growth factor 1
- Performance-enhancing substance
- Selective androgen receptor modulator
- World Anti-Doping Agency
References
- a b World Anti-Doping Agency. (2026). "Prohibited List 2026." Retrieved 12 May 2026.
- a b c Natural Bodybuilding Federation rulebook (2025 ed.). §4.2 Banned Substances.
- ^ Sikiric, P. et al. (2024). "Cytoprotection by BPC 157: a systematic review." PMC.
- Wilding, J. P. H. et al. (2021). "Once-weekly semaglutide in adults with overweight or obesity." NEJM, 384(11):989–1002.
- U.S. Food and Drug Administration. "Compounded peptides advisory" (2025).
External links
- World Anti-Doping Agency — official site
- PubMed — biomedical literature index
- ClinicalTrials.gov
- Examine.com
This page was last updated on September 4, 2026, at 13:25 (UTC).
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