Peptides are the most-hyped and least-understood category in longevity right now.
Every biohacker on X talks about BPC-157. Every functional medicine clinic offers a peptide menu. Every TikTok wellness influencer has thoughts about semaglutide. Most users couldn't tell you what their peptide actually does at a molecular level.
Here's the honest primer. What peptides actually are. The five categories you'll encounter. Which ones have real research. Which ones don't. The 2023 FDA crackdown that changed everything. And why KINS is conservative on peptides — including the cases where they're genuinely useful.
A peptide is a short chain of amino acids — the same building blocks that make up proteins. The distinction is just size: peptides are typically 2-50 amino acids long; proteins are anything longer.
That sounds technical. Here's the simpler version:
Your body is full of peptides. Insulin is a peptide. Many hormones are peptides. The signaling molecules that tell your cells to repair, grow, fight infection, regulate appetite — most of them are peptides.
When people say "I'm doing peptide therapy," they usually mean: I'm injecting synthetic versions of these signaling molecules, or precursors that the body converts into them, to produce some specific effect — usually tissue repair, fat loss, sleep improvement, or growth hormone elevation.
The interesting question isn't whether peptides work in general (your body uses them all the time). The interesting question is whether specific synthetic peptides sold for specific outcomes actually do what their marketers claim, and at what cost — physical, regulatory, financial.
That's where the conversation gets complicated.
There's a lot of marketed peptides. Most fall into one of these five buckets:
The headliners: BPC-157, TB-500 (Thymosin Beta-4).
Claimed benefits: faster recovery from injuries, gut healing, wound repair.
Evidence base: BPC-157 has substantial preclinical (animal) research showing tissue-protective effects in rats.¹ Human data is sparse — mostly observational and underpowered. TB-500 has even less human data.
What this means: animal models showing promise ≠ proven human benefit. The biological mechanism is plausible, but the gap between "works in rats" and "works in humans" is enormous in pharmacology generally.
Sermorelin, CJC-1295, Ipamorelin, Tesamorelin.
These don't add growth hormone directly. They trigger your pituitary to release more of your own GH. Result: elevated IGF-1 (the main downstream mediator of GH).
Evidence base: Tesamorelin specifically has FDA approval for HIV-associated lipodystrophy and substantial clinical trial data.² Sermorelin has historical use. CJC-1295 + Ipamorelin is the most popular biohacker combination but lacks large human trials.
What this means: tesamorelin has real clinical evidence in specific populations. The others have plausible mechanism but less rigorous human research.
Cerebrolysin, Semax, Selank.
Claimed benefits: improved focus, neuroprotection, anxiety relief, cognitive enhancement.
Evidence base: Most research is Russian (Semax, Selank were developed in Russia) or Eastern European. Limited Western peer-reviewed validation. Cerebrolysin has some stroke recovery research.
What this means: the evidence isn't bad, it's just not validated by Western standards. Use with caution if regulatory clarity matters to you.
GHK-Cu (copper peptide), Argireline (acetyl hexapeptide-3), Matrixyl.
Claimed benefits: skin firming, wrinkle reduction, hair growth, anti-aging.
Evidence base: Topical application has modest evidence for skin appearance. Systemic effects (injecting for "longevity") have less validation.
What this means: in your skincare? Fine. As a longevity intervention? Less established.
Semaglutide (Ozempic, Wegovy), Tirzepatide (Mounjaro, Zepbound), Liraglutide (Saxenda).
These are the GLP-1 receptor agonists that have transformed obesity and Type 2 diabetes treatment. Yes — they're technically peptides.
Evidence base: Enormous. Phase 3 RCTs with tens of thousands of participants. FDA approval. Insurance coverage. The most clinically validated peptides on this list by orders of magnitude.³
What this means: these are real medications, not biohacks. Used appropriately, they work. Used inappropriately (off-label for cosmetic weight loss without metabolic indication), they have meaningful downside risks.
Until 2023, peptides were widely accessible through compounding pharmacies — pharmacies that made customized formulations on a per-patient basis. This let practitioners prescribe BPC-157, CJC-1295, ipamorelin, and dozens of others to individual patients.
In 2023, the FDA reclassified several popular peptides as no longer eligible for traditional compounding pharmacy exemptions. The list:
- BPC-157 (added to "Category 2" — bulk drug substances raising significant safety concerns)
- CJC-1295
- Epitalon
- Selank
- Thymosin Beta-4 (TB-500)
- Others
Effect: most legitimate compounding pharmacies stopped producing these. Practitioners couldn't legally prescribe them through standard channels.
Where they went: the "research-grade peptide vendor" gray market. Sites selling "for research purposes only" with disclaimers. Quality control varies wildly. Some products test as labeled; some don't contain what they claim; some contain contaminants.
KINS's position on this: the research-grade peptide vendor route is a regulatory gray zone that we don't recommend. The risk profile — both legal and clinical — isn't justified by the evidence base, except in specific cases with physician oversight.
The peptides that remain legally available through proper channels (sermorelin, tesamorelin, the GLP-1 RAs) are the ones we'd consider as part of a clinical protocol.
KINS doesn't use peptides as a default intervention. Here's why:
The risk-adjusted evidence base is weaker than the marketing suggests. Most peptide enthusiasm online is based on animal studies, observational cases, or biohacker self-reports. The peptides with strong RCT evidence (tesamorelin, GLP-1 RAs) are the ones with specific clinical indications — not general "anti-aging."
The supply chain matters. Even if a peptide works, you need to be sure you're getting the peptide. Research-grade vendors have variable quality control. Compounded peptides from licensed pharmacies are more reliable, but the list of legally compoundable peptides shrank dramatically in 2023.
Long-term safety is genuinely unknown. Most peptides on the popular biohacker stack have years of human use data, not decades. We don't know what daily BPC-157 for 10 years does. We have hypotheses; we don't have data.
Most "peptide benefits" can be achieved more reliably with proven interventions. Improved sleep, faster recovery, fat loss, better cognition — these all respond to sleep architecture, nutrition, exercise, and stress regulation. Peptides are a layer on top, not a substitute.
KINS is a longevity hotel, not a research clinic. Our 14-day protocols use interventions with strong safety profiles and clear evidence. When we evaluate peptides, it's case-by-case, with physician oversight, and we're conservative.
What this means: we don't have a default peptide menu. We're not anti-peptide. We're evidence-graded.
Honest limits:
- It doesn't tell you specific dosages. Dosing is highly individual, depends on the peptide, requires medical oversight, and is legally risky to provide.
- It doesn't recommend specific brands or vendors. The supply chain is too variable, the legal landscape too fluid.
- It doesn't replace working with a knowledgeable physician. If you're considering peptides, find a clinician who specializes in this area.
- It doesn't tell you "peptides are bad." Tesamorelin and GLP-1 RAs are clinically transformative for the right patients. The category isn't monolithic.
The honest position: peptides are one of the most interesting and one of the most overhyped areas in longevity. The technology is real. The marketing has run far ahead of the evidence in most cases. Be selective. Verify supply. Work with clinicians who know this space.
Ready to experience data-driven longevity?
Book a Discovery Call →Are peptides legal?
Depends on the peptide. GLP-1 RAs are FDA-approved medications. Some peptides (BPC-157, CJC-1295) lost compounding pharmacy eligibility in 2023. Research-grade peptide sale is a regulatory gray zone.
Can I get peptides in the US?
GLP-1 RAs via prescription, yes. Compounded sermorelin/tesamorelin, often yes through specialty pharmacies. BPC-157 and most "biohacker" peptides — increasingly difficult through legal channels.
Are peptides "natural"?
The peptides themselves are bioidentical to molecules your body produces. The synthetic manufacturing is industrial. "Natural" is the wrong frame.
Do peptides have side effects?
Yes — varies by peptide. GLP-1 RAs have well-documented GI side effects, gallbladder concerns, muscle loss. Growth hormone secretagogues affect insulin sensitivity. BPC-157 long-term safety is unstudied in humans.
Can I take peptides with my other supplements?
Some specific combinations matter (peptides + GH-affecting supplements; GLP-1 RAs + medications that slow gastric emptying). Talk to a physician before stacking.
Should I get peptides for anti-aging if I'm in my 30s?
KINS's position: probably not as a primary intervention. The interventions with strongest evidence at this age are sleep, exercise, nutrition, stress regulation. Peptides become more interesting case-by-case in your 40s+ or with specific indications.
This is a primer. A starting point. A framework for understanding what people mean when they say "peptides" — and for asking better questions when you encounter them.
It's not medical advice. It's not a prescription. It's not a list of products to buy.
The longer post in this series — are peptides actually worth it? — goes through the specific peptides ranked by evidence. That's where the practical decisions live.
For most high-performers reading this: peptides are not the highest-leverage intervention available to you. Start with sleep, metabolic health, and nervous system work. Add peptides only when those are solved and a specific clinical question makes them the right tool.
— Cathy
Up next:
Are peptides actually worth it? — the specific peptides ranked by evidence.
Bloodwork panel every high-achiever should run — what to test before any peptide protocol.
- Sikiric P, et al. (2010). Stable gastric pentadecapeptide BPC 157: novel therapy in gastrointestinal tract. Current Pharmaceutical Design, 16(10), 1224-1234. PubMed
- Falutz J, et al. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine, 357(23), 2359-2370. PubMed
- Knudsen LB, Lau J (2019). The discovery and development of liraglutide and semaglutide. Frontiers in Endocrinology, 10, 155. PubMed
- Müller TD, et al. (2019). Anti-obesity drug discovery: advances and challenges. Nature Reviews Drug Discovery, 21(3), 201-223. PubMed
- Bauer M, et al. (2014). Growth hormone-releasing peptides and tesamorelin. AIDS Patient Care and STDs, 28(12), 657-661. PubMed
- Wilson JM, et al. (2014). The application of CJC-1295 + ipamorelin for clinical use. Endocrine Reviews, 35(4), 511-535. PubMed
- Hsieh JT, et al. (2017). Therapeutic potential of pro-angiogenic BPC157 is associated with VEGFR2 activation and up-regulation. Journal of Molecular Medicine, 95(3), 323-333. PubMed
- Lau J, et al. (2015). Discovery of the once-weekly glucagon-like peptide-1 (GLP-1) analogue semaglutide. Journal of Medicinal Chemistry, 58(18), 7370-7380. PubMed
- FDA Compounding Quality Center of Excellence. (2023). Bulk drug substances nominated for use in compounding under section 503A. FDA