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Peptides for Biohackers: A Comprehensive Guide

Biohacking has moved from basement experiments and self-quantification apps into mainstream health culture. And at the center of the movement's latest obsession sits a class of molecules that the body already makes: peptides.

Biohacking has moved from basement experiments and self-quantification apps into mainstream health culture. And at the center of the movement's latest obsession sits a class of molecules that the body already makes: peptides.

Short chains of amino acids, peptides act as molecular signals that tell your cells what to do. They control tissue repair, metabolism, immune defense, sleep architecture, and cognitive performance. The reason biohackers care about them is simple: as you age, your body produces fewer of these signals, and the ones it does produce become less effective. Peptide therapy is an attempt to restore what time has taken away — or push performance beyond baseline.

But the hype has outpaced the evidence in some cases. Injectable peptides are now a multibillion-dollar gray market, with U.S. customs data showing imports of hormone and peptide compounds from China roughly doubling to $328 million in the first three quarters of 2025 [1]. Online advertising of unauthorized peptide formulations grew nearly eightfold from 2022 to 2024 [1].

This guide breaks down the peptides biohackers actually use, what the research says about each one, and where the science ends and speculation begins.

Table of Contents

What Makes Peptides Different from Other Biohacks {#what-makes-peptides-different-from-other-biohacks}

Most biohacking tools work from the outside in. Cold plunges trigger a stress response. Supplements provide raw materials. Wearables track outputs. Peptides work differently — they communicate directly with your cells using the same language your body already speaks.

Each peptide targets a specific receptor or signaling pathway. BPC-157 binds to growth factor receptors involved in tissue healing. Semaglutide activates GLP-1 receptors that regulate appetite and blood sugar. Semax boosts BDNF (brain-derived neurotrophic factor) in the hippocampus. This specificity is what makes peptides attractive to biohackers who want targeted effects rather than broad systemic changes.

The precision cuts both ways, though. Because peptides target defined pathways, stacking the wrong ones can create unpredictable interactions. And because most peptides require injection — oral bioavailability is poor for many of them — the barrier to entry is higher than popping a supplement.

Recovery and Tissue Repair Peptides {#recovery-and-tissue-repair-peptides}

BPC-157

BPC-157 (Body Protection Compound-157) is probably the most discussed peptide in biohacking circles, and for good reason. It is a 15-amino-acid peptide derived from a protective protein found in human gastric juice.

What the research shows: A 2025 systematic review in HSS Journal analyzed 36 studies on BPC-157 in orthopedic medicine. Thirty-five were preclinical (animal models), and one was a small human retrospective study. In animal models, BPC-157 improved functional, structural, and biomechanical outcomes in muscle, tendon, ligament, and bone injuries. It appears to work by boosting growth hormone receptor expression, promoting angiogenesis (new blood vessel formation), and reducing inflammatory cytokines [2].

The single human study was a retrospective chart review: 7 of 12 patients with chronic knee pain reported pain relief lasting more than 6 months after intra-articular BPC-157 injection [2]. A 2025 pilot safety study gave two healthy adults intravenous BPC-157 infusions up to 20 mg with no adverse events observed [3].

The biohacker angle: BPC-157 is popular for accelerating recovery from training injuries, gut issues, and tendon problems. Many users report faster wound healing and reduced joint pain.

Reality check: The preclinical data is strong, but human evidence is thin. The FDA classified BPC-157 as a Category 2 bulk drug substance in 2023, meaning compounding pharmacies cannot legally produce it for human use [2].

TB-500

TB-500 is a synthetic fragment of thymosin beta-4, a 43-amino-acid protein your body naturally produces. Where BPC-157 tends to work locally at the site of injury, TB-500 is thought to act systemically — supporting broader recovery through improved circulation, reduced inflammation, and enhanced cell migration [4].

What the research shows: Preclinical studies demonstrate that TB-500 promotes tissue organization and new blood vessel growth. It increases the protein actin, which is fundamental to cellular movement and repair. In animal models of cardiac injury, thymosin beta-4 has shown the ability to reactivate dormant cardiac progenitor cells [4].

The biohacker angle: TB-500 is often combined with BPC-157 in what biohackers call the "recovery stack." The idea is to get both localized repair (BPC-157) and systemic healing support (TB-500). A small retrospective study found that 14 of 16 knee pain patients (87.5%) reported relief when BPC-157 or a combination of BPC-157 and TB-500 was used as intra-articular injections [5].

For a deeper look at combining these and other peptides, see the Peptide Stacking Guide.

Metabolic Optimization and Body Composition {#metabolic-optimization-and-body-composition}

Semaglutide and Microdosing GLP-1s

Semaglutide needs no introduction. Originally developed for type 2 diabetes, GLP-1 receptor agonists like semaglutide and tirzepatide have become household names for weight management. But in biohacking circles, the interest has shifted to microdosing — using one-fifth to one-tenth of the standard dose to capture metabolic benefits while minimizing side effects.

What the research shows: GLP-1 receptors are distributed throughout the brain, and their activation influences appetite control, glucose metabolism, cardiovascular function, mood regulation, and cognitive function [6]. Preclinical models show GLP-1 receptor agonists reduce amyloid-beta plaque deposition, dampen neuroinflammation, and support synaptic plasticity [6]. Semaglutide improved memory in Alzheimer's disease rodent models by activating the GLP-1/SIRT1/GLUT4 pathway [6].

The biohacker angle: Microdosing GLP-1s is one of the fastest-growing trends in biohacking. The logic: sustained, low-level receptor activation could maintain insulin sensitivity, reduce chronic inflammation (lowering markers like CRP and IL-6), and support brain health without the aggressive appetite suppression and muscle loss that come with full therapeutic doses [7]. Many users describe a "quieting of food noise" — the constant mental chatter about eating that fades even at low doses [7].

Reality check: Dedicated clinical trials on GLP-1 microdosing are only just beginning. Most research focuses on standard and maximum doses, so the long-term safety and efficacy of microdosing protocols remain unestablished [7].

AOD-9604

AOD-9604 is a modified fragment of human growth hormone (amino acids 177-191) that was designed to isolate the fat-burning properties of GH without the muscle-building or blood sugar effects. It received generally-recognized-as-safe (GRAS) status from the FDA as a food supplement.

What the research shows: Early clinical trials showed modest fat reduction, particularly in the abdominal region. AOD-9604 appears to stimulate lipolysis (fat breakdown) and inhibit lipogenesis (fat creation) without affecting blood sugar or IGF-1 levels. However, a Phase IIb clinical trial for obesity failed to show significant weight loss compared to placebo [8].

The biohacker angle: AOD-9604 appeals to biohackers who want a lighter touch on body composition — fat loss without the systemic effects of full GH or the appetite disruption of GLP-1 drugs. It is available in both injectable and oral forms. For a broader look at fat loss peptides, see the Best Peptides for Fat Loss guide.

Growth Hormone Secretagogues {#growth-hormone-secretagogues}

Growth hormone (GH) production drops roughly 14% per decade after age 30. Rather than injecting exogenous GH (which carries real risks), biohackers have turned to secretagogues — peptides that stimulate your pituitary gland to produce more of its own GH.

CJC-1295 + Ipamorelin

This is the most popular GH secretagogue stack in biohacking. CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) with a half-life of 5.8 to 8.1 days, meaning a single injection can sustain elevated GH levels for nearly a week. Ipamorelin is a selective growth hormone-releasing peptide (GHRP) that triggers short, pulsatile GH bursts by mimicking ghrelin.

What the research shows: A clinical study found that a single CJC-1295 injection produced dose-dependent increases in plasma GH concentrations of 2- to 10-fold for 6 or more days and IGF-I increases of 1.5- to 3-fold for 9 to 11 days. After multiple doses, IGF-I remained elevated above baseline for up to 28 days [9]. Ipamorelin's advantage over older GHRPs (like GHRP-6) is its clean side-effect profile — it doesn't spike cortisol or prolactin and avoids the intense hunger that GHRP-6 causes [10].

The biohacker angle: Users report improved sleep quality (particularly deep slow-wave sleep), faster recovery from training, and gradual improvements in body composition. The combination works because CJC-1295 provides the sustained baseline elevation while ipamorelin delivers the acute pulses — "the tortoise and the hare as relay partners" [10].

Reality check: Human studies confirm that CJC-1295 and ipamorelin change hormone levels. What they don't conclusively show is whether those hormonal changes translate into meaningful improvements in muscle mass, strength, or fat loss in healthy, trained adults [10]. The FDA has flagged both peptides for safety concerns, including potential immunogenicity and, in the case of CJC-1295 specifically, risks of increased heart rate and systemic vasodilatory reactions [10]. One death occurred during Phase II clinical trials of CJC-1295 [11].

Other GH Secretagogues

PeptideTypeKey FeatureResearch Status
SermorelinGHRH analogShorter half-life, more physiological GH pulsesPreviously FDA-approved for GH deficiency in children (discontinued)
TesamorelinGHRH analogFDA-approved for HIV lipodystrophyThe only FDA-approved GHRH analog currently on the market
MK-677Ghrelin mimetic (oral)Oral bioavailability, no injection neededExtensive clinical trial data; increases GH and IGF-1 but also hunger and insulin resistance

For athletes interested in GH peptides, see Peptides for Athletic Performance and Peptides for Bodybuilding.

Cognitive Enhancement Peptides {#cognitive-enhancement-peptides}

Nootropic peptides are among the most underappreciated tools in the biohacker's kit. Unlike stimulants that borrow energy from tomorrow, peptides like Semax and Selank work by modulating neurotransmitter systems and neurotrophic factors.

Semax

Semax is a seven-amino-acid peptide analog of ACTH (adrenocorticotropic hormone) that retains the brain-growth-supporting effects of ACTH without its hormonal activity. Developed in Russia in the 1980s, Semax has been used clinically there for stroke recovery and cognitive impairment.

What the research shows: Semax rapidly increases the expression of BDNF and other neurotrophic factors in the hippocampus, which supports neuroplasticity — the brain's ability to form new neural connections [12]. It increases dopamine levels, influencing motivation and cognitive processing, without affecting cortisol [12]. An fMRI study in 52 healthy participants showed that Semax produced measurable changes in functional connectivity between the amygdala and temporal cortex regions within 20 minutes of administration [12].

The biohacker angle: Semax is administered intranasally (oral bioavailability is nearly zero). Most users cycle it in 5- to 14-day protocols, taking the 0.1% solution for cognitive support. It is not designed for continuous long-term daily use.

Selank

Selank is a synthetic peptide derived from tuftsin, a naturally occurring immunomodulatory peptide. Where Semax is the cognitive accelerator, Selank is the emotional stabilizer.

What the research shows: Selank modulates GABA-A receptors — the brain's primary inhibitory system — to reduce anxiety without the sedation, cognitive impairment, or dependency risk associated with benzodiazepines [13]. It also balances serotonin and norepinephrine activity and has immune-modulating properties through interleukin-6 induction [13].

The biohacker angle: The Semax + Selank stack is popular for what users describe as "focused calm" — cognitive drive without anxiety. Semax provides the mental energy and memory support; Selank prevents that drive from tipping into stress or overstimulation. For a broader look at cognitive peptides, see Best Peptides for Cognitive Enhancement.

DSIP

DSIP (Delta Sleep-Inducing Peptide) targets sleep architecture directly. Rather than sedation, it appears to promote the natural transition into deep, restorative slow-wave sleep. Biohackers who track sleep with devices like the Oura Ring or WHOOP often experiment with DSIP to optimize deep sleep percentages. For more on this topic, see Best Peptides for Sleep.

Mitochondrial and Longevity Peptides {#mitochondrial-and-longevity-peptides}

This is where biohacking intersects with longevity science. Mitochondrial decline is one of the hallmarks of aging, and several peptides target this process directly.

MOTS-c

MOTS-c is a 16-amino-acid peptide encoded by mitochondrial DNA. Your body produces it naturally, but levels drop with age — blood MOTS-c levels in young people are 11% to 21% higher than in middle-aged and older adults [14].

What the research shows: MOTS-c activates AMPK, SIRT1, and PGC-1alpha — the same signaling intermediaries that exercise and caloric restriction activate [14]. In aged mice, MOTS-c treatment substantially improved treadmill endurance and performance. It has earned the nickname "exercise mimetic" because it replicates many cellular benefits of physical activity, including improved glucose utilization and mitochondrial biogenesis [14]. A 2025 study in Experimental & Molecular Medicine found MOTS-c reduced pancreatic islet cell senescence and improved glucose intolerance in aged mice [15].

SS-31 (Elamipretide)

SS-31 takes a different approach. Instead of modulating gene expression like MOTS-c, it directly stabilizes mitochondrial membranes. A single treatment restored mitochondrial ATP production and oxidative phosphorylation coupling in aged mice to levels seen in young animals — within one hour [16]. Eight days of treatment increased whole-animal endurance capacity [16].

SS-31 has received orphan drug designations for conditions like Friedreich ataxia and Duchenne muscular dystrophy and has undergone several human clinical trials with a favorable short-term safety profile [16].

Epitalon

Epitalon is the longevity peptide most biohackers know about. This synthetic tetrapeptide (Ala-Glu-Asp-Gly) was developed at the St. Petersburg Institute of Bioregulation and Gerontology.

What the research shows: Epitalon activates telomerase, the enzyme that rebuilds telomeres — the protective caps at the ends of chromosomes that shorten with each cell division. In human fibroblast cell cultures, epitalon-induced telomere elongation was sufficient to surpass the Hayflick limit (the maximum number of cell divisions) [17]. In human clinical studies, both epitalon and its parent compound epithalamin significantly increased telomere lengths in blood cells of patients aged 60 to 80 [17]. A 2025 study in Biogerontology provided new quantitative data showing dose-dependent telomere extension across multiple cell types [18].

Beyond telomeres, epitalon acts on at least five hallmarks of aging: telomere maintenance, epigenetic regulation, oxidative stress resilience, immune recalibration, and circadian rhythm restoration [17]. It also appears to restore melatonin secretion by the pineal gland in both aged monkeys and humans [17].

For more on longevity peptides, see Best Peptides for Anti-Aging & Longevity and the profiles for Humanin and SS-31.

Immune System Peptides {#immune-system-peptides}

Thymosin Alpha-1

Thymosin Alpha-1 is a peptide hormone produced by the thymus gland — the organ that trains your immune system's T cells. The thymus begins shrinking after puberty, and by age 50, most people have significantly reduced thymic output. Thymosin Alpha-1 acts as a replacement signal, stimulating T-cell differentiation, enhancing thymic output, and modulating dendritic cell and macrophage activity [19].

What the research shows: In double-blind, placebo-controlled trials, Thymosin Alpha-1 improved influenza vaccine antibody responses in elderly subjects [20]. During the COVID-19 pandemic, it was shown to reduce mortality in elderly patients and upregulate immune activation markers on plasmacytoid dendritic cells [19]. It is one of the few peptides approved as a pharmaceutical product in over 35 countries (though not the U.S.) for hepatitis B, hepatitis C, and as a vaccine adjuvant [19].

LL-37

LL-37 is the only cathelicidin antimicrobial peptide found in humans. It punches holes in bacterial membranes and modulates immune responses. Biohackers interested in immune resilience sometimes use it alongside Thymosin Alpha-1.

For broader immune support options, see Best Peptides for Immune Support.

Peptide Stacking: Combining for Synergy {#peptide-stacking-combining-for-synergy}

Biohackers rarely use a single peptide in isolation. Stacking — using multiple peptides that target complementary pathways — is common practice. Here are the most popular biohacker stacks:

StackPeptidesTargetRationale
Recovery StackBPC-157 + TB-500Injury repairLocal repair (BPC-157) + systemic healing (TB-500)
GH StackCJC-1295 + IpamorelinGrowth hormoneSustained baseline (CJC-1295) + acute pulses (Ipamorelin)
Cognitive StackSemax + SelankBrain performanceCognitive drive (Semax) + emotional balance (Selank)
Longevity StackEpitalon + MOTS-cCellular agingTelomere maintenance (Epitalon) + mitochondrial support (MOTS-c)
Metabolic StackSemaglutide (microdose) + AOD-9604Body compositionGLP-1 metabolic support + targeted fat metabolism

A word of caution: Stacking is based largely on theoretical complementarity and anecdotal reports. Clinical trials studying peptide combinations are virtually nonexistent. The more peptides you combine, the less predictable the outcome. Start with one, assess your response, and add slowly. For detailed stacking protocols, see the Peptide Stacking Guide.

This is where the conversation gets uncomfortable. The biohacking community's enthusiasm for peptides has created a thriving gray market that operates largely outside regulatory oversight.

Regulatory Status

Most peptides used by biohackers — including BPC-157, TB-500, CJC-1295, Ipamorelin, Selank, Semax, and Epitalon — are not FDA-approved for any human use. GLP-1 agonists like semaglutide and tirzepatide are notable exceptions, carrying full FDA approval for specific indications. Tesamorelin is FDA-approved for HIV-associated lipodystrophy.

In 2023, the FDA moved several popular peptides to Category 2, effectively banning their production by compounding pharmacies. This pushed more buyers toward unregulated "research chemical" vendors.

Sourcing Risks

The quality of peptides from unregulated sources varies wildly. Common problems include:

  • Contamination — bacterial endotoxins, heavy metals, or other peptide fragments
  • Underdosing or mislabeling — getting less than what you paid for, or a different peptide entirely
  • Degradation — peptides are fragile molecules that degrade with heat, light, and time
  • No third-party testing — many vendors claim "99% purity" without independent verification

What Responsible Biohackers Do

  1. Work with a physician. Ideally one trained in peptide therapy who can monitor bloodwork and adjust protocols.
  2. Demand certificates of analysis (COAs) from independent, third-party labs — not the manufacturer's in-house testing.
  3. Start low and go slow. Begin with conservative doses and a single peptide before stacking.
  4. Track biomarkers. Regular bloodwork (CBC, CMP, IGF-1, inflammatory markers, hormone panels) is non-negotiable.
  5. Accept the uncertainty. For most of these peptides, you are the clinical trial.

FAQ {#faq}

Are peptides legal to buy and use? It depends on the peptide and jurisdiction. FDA-approved peptides like semaglutide require a prescription. Many others are sold as "research chemicals not for human consumption." Purchasing them is generally legal; using them on yourself exists in a gray area. Working with a licensed provider is the safest approach.

How are most peptides administered? The majority require subcutaneous injection. Some — like Semax and Selank — are administered intranasally. A few, like MK-677 and AOD-9604, are available orally. Topical application is used for GHK-Cu in skincare formulations.

How long before I notice effects? It varies by peptide and goal. BPC-157 users often report faster recovery within 1 to 2 weeks. GH secretagogue effects on sleep may appear within days, but body composition changes typically take 8 to 12 weeks. Cognitive peptides like Semax may produce noticeable effects within hours.

Can I take peptides with other supplements? Generally yes, but interactions are understudied. The biggest concern is combining multiple peptides that affect the same pathway. For example, stacking CJC-1295 + Ipamorelin + MK-677 could overstimulate GH production.

Are peptides safe? The answer depends entirely on which peptide, what dose, what source, and your individual health status. FDA-approved peptides have well-characterized safety profiles. Research peptides have animal safety data but limited human evidence. "Safe" and "FDA-approved" are different claims.

Do I need blood work before starting peptides? Yes. Baseline labs help you and your doctor track changes and catch problems early. At minimum: complete blood count, comprehensive metabolic panel, fasting insulin, IGF-1, thyroid panel, and inflammatory markers (CRP, IL-6).

The Bottom Line {#the-bottom-line}

Peptides represent a genuinely different category of biohacking tool. They speak the body's native language, target specific pathways, and — in some cases — have meaningful research behind them.

But the gap between what we know and what the market sells is wide. GLP-1 drugs have robust Phase III clinical trial data supporting their use. Thymosin Alpha-1 has decades of clinical research and pharmaceutical approval in dozens of countries. Epitalon has intriguing telomerase data from multiple human studies. On the other end of the spectrum, many popular peptides rest almost entirely on preclinical animal research and biohacker anecdotes.

The biohackers getting the most out of peptide therapy are the ones who treat it like what it is: an experiment requiring medical supervision, quality sourcing, careful tracking, and intellectual honesty about what the evidence actually supports. Training, sleep, nutrition, and stress management remain the foundation. Peptides are tools you add on top of that foundation — not substitutes for it.

References {#references}

  1. Marketplace.org. "Peptides are the new 'biohacking' trend in tech." January 2026.
  2. Vasireddi N, et al. "Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review." HSS Journal. 2025. PMID: 40756949.
  3. Lee M, Burgess A. "BPC-157 pilot safety study in healthy adults." Referenced in: "Regeneration or Risk? A Narrative Review of BPC-157 for Musculoskeletal Healing." PMC. 2025.
  4. Tyranceorthopedics.com. "Peptides BPC-157 and TB-500." Clinical overview.
  5. Hauser RA. "Intra-Articular Injection of BPC 157 for Multiple Types of Knee Pain." J Prolother. 2021. PMID: 34324435.
  6. Athanasios A, et al. "A Systematic Review of Semaglutide's Influence on Cognitive Function in Preclinical Animal Models and Cell-Line Studies." PMC. 2024. PMC11084700.
  7. Signos.com. "Microdosing GLP-1s: What It Is, Why It's Trending, and What Science Actually Says." 2025.
  8. Heffernan M, et al. "The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and humans." Endocrinology. 2001.
  9. Teichman SL, et al. "Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults." J Clin Endocrinol Metab. 2006. PMID: 16352683.
  10. Innerbody.com. "CJC-1295 + Ipamorelin | Benefits, Safety & Buying Advice." 2026 review.
  11. CJC-1295 Wikipedia entry. Phase II clinical trial information.
  12. Dolotov OV, et al. "Functional Connectomic Approach to Studying Selank and Semax Effects." Dokl Biol Sci. 2020. PMID: 32342318.
  13. Livvnatural.com. "Selank vs. Semax: Which Nootropic Peptide Is Right for You?" Clinical comparison.
  14. Merry TL, et al. "MOTS-c: A promising mitochondrial-derived peptide for therapeutic exploitation." PMC. 2023. PMC9905433.
  15. Kim SH, et al. "Mitochondrial-encoded peptide MOTS-c prevents pancreatic islet cell senescence to delay diabetes." Exp Mol Med. 2025.
  16. Siegel MP, et al. "Mitochondrial targeted peptide rapidly improves mitochondrial energetics and skeletal muscle performance in aged mice." Aging Cell. 2013. PMC3772966.
  17. Khavinson VKh, et al. "Epithalon peptide induces telomerase activity and telomere elongation in human somatic cells." Bull Exp Biol Med. 2003. PMID: 12937682.
  18. "Epitalon increases telomere length in human cell lines through telomerase upregulation or ALT activity." Biogerontology. 2025.
  19. MDPI. "Aging and Thymosin Alpha-1." Int J Mol Sci. 2025. PMC12692621.
  20. Gravenstein S, et al. "Augmentation of influenza antibody response in elderly men by thymosin alpha one." J Am Geriatr Soc. 1989. PMID: 2642497.