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 30 compounds frequently encountered in the peptide marketplace, the function each is researched for, and the verdict of the present rulebook.
Contents [hide]
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. Early studies on metabolism and mitochondrial function show mixed results. Cellular benefits proven, human longevity unproven. | Natty |
| #2 | Ozempic | Reduces appetite and slows digestion for 15-21% weight loss. Improves blood sugar control. Lowers heart attack and stroke risk by 20%. | Natty |
| #3 | Tirzepatide | Dual GIP/GLP-1 agonist for weight loss of up to about 21% and better blood sugar control. First drug approved for obstructive sleep apnea. GI side effects common. | Natty |
| #4 | HCG | Mimics luteinizing hormone to make the testes produce testosterone and to trigger final egg maturation and ovulation. FDA-approved for fertility and hypogonadism. Not effective for weight loss. | Not natty |
| #5 | 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 |
| #6 | 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 |
| #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 | 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 |
| #9 | 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 |
| #10 | KPV | Anti-inflammatory tripeptide from alpha-MSH. Dampens NF-κB inflammatory signaling and lowers pro-inflammatory cytokines in cell and animal studies. Researched for gut and skin inflammation and wound healing. | Not natty |
| #11 | 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 |
| #12 | 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 |
| #13 | 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 |
| #14 | TB-500 | Speeds wound healing, muscle and tendon recovery. Reduces inflammation, improves joint mobility, minimizes scar tissue formation. | Not natty |
| #15 | 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 |
| #16 | Cagrilintide | Long-acting amylin analogue that signals fullness and reduces body weight. Given as a once-weekly subcutaneous injection. Investigational for obesity and type 2 diabetes, alone or with semaglutide. | Not natty |
| #17 | Kisspeptin | Signals the hypothalamus to release GnRH. This drives pituitary secretion of LH and FSH, the hormones behind reproductive maturation and egg and sperm production. Studied in puberty research. | Not natty |
| #18 | Cerebrolysin | Used as a therapy after stroke, traumatic brain injury, and in dementia. Pig brain-derived peptide mixture that can include neurotrophic factors. Given by intramuscular injection or intravenous infusion. | Not natty |
| #19 | 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 |
| #20 | SS-31 | Binds cardiolipin in mitochondria, proposed to stabilize energy production and reduce oxidative stress. Has accelerated FDA approval to improve muscle strength in Barth syndrome. Investigational for other uses. | Not natty |
| #21 | 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 |
| #22 | Melanotan II | Stimulates melanin production to darken skin and facilitate tanning. May also increase arousal and reduce appetite. Unapproved for human use; linked to nausea and mole changes. | Not natty |
| #23 | 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 |
| #24 | 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 |
| #25 | AOD-9604 | Growth hormone fragment designed to promote fat breakdown without effects on growth, blood sugar, or IGF-1. A 24-week obesity trial found no significant weight loss over placebo. | Not natty |
| #26 | 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 |
| #27 | Bremelanotide | FDA-approved (as Vyleesi) for low libido in premenopausal women. Activates central melanocortin receptors to drive arousal. Shows preclinical promise for erectile dysfunction. Given by subcutaneous injection. | Natty |
| #28 | 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 |
| #29 | GHRP-6 | Stimulates the pituitary to release growth hormone by mimicking ghrelin at its receptor. Also increases appetite. May slightly raise cortisol and prolactin. Given by subcutaneous injection. | Not natty |
| #30 | 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 |
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
See also: Therapeutic use exemption
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
Categories:
Peptides |
Performance-enhancing substances |
Natural bodybuilding |
Anti-doping |
Bioactive molecules
This page was last updated on October 24, 2026, at 03:04 (UTC).
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