The Peptide World: 49 Compounds Explained

1. 5-Amino-1MQ

2. AICAR

3. AOD-9604

4. Berberine

5. BPC-157

6. Cardarine (GW501516)

7. Cerebrolysin

8. CJC-1295

9. Dihexa

10. DSIP (Delta Sleep-Inducing Peptide)

11. Epithalon

12. Follistatin 344

13. GHK-Cu

14. GHRP-2

15. GHRP-6

16. Glutathione

17. Humanin

18. IGF-1 LR3

19. Ipamorelin

20. Kisspeptin-10

21. KPV

22. Liraglutide

23. LL-37

24. Melanotan II

25. MGF (Mechano Growth Factor)

26. MitoQ

27. MK-677 (Ibutamoren)

28. MOTS-c

29. NAD+ (NMN, NR)

30. Noopept

31. Oxytocin

32. P21

33. PT-141 (Bremelanotide)

34. Retatrutide

35. Selank

36. Semax

37. Sermorelin

38. SLU-PP-332

39. SR9009 (Stenabolic)

40. SS-31 (Elamipretide)

41. TB-500 (Thymosin Beta-4)

42. Tesamorelin

43. Tesofensine

44. Thymalin

45. Thymosin Alpha-1 (TA-1)

46. Tirzepatide

47. Urolithin A

48. VIP (Vasoactive Intestinal Peptide)

49. Semaglutide

    
    

CATEGORY 1: GH AXIS AND ANABOLIC

These compounds work on the growth hormone axis, either by stimulating the pituitary to release more GH, mimicking the signals that trigger that release, or acting downstream on IGF-1 receptors to drive tissue growth and repair.

Ipamorelin

The Science: Ipamorelin is a pentapeptide ghrelin mimetic that selectively binds the GH secretagogue receptor (GHSR-1a) in the pituitary, triggering pulsatile GH release. Its key distinction from older GHRPs is its selectivity: it does not meaningfully raise cortisol, prolactin, or ACTH at therapeutic doses, making it one of the cleanest GH stimulants available. The resulting GH pulse is physiological in character, preserving the natural feedback architecture of the axis.

Plain English: Ipamorelin tells your pituitary gland to release growth hormone in a clean, controlled burst, the same way your body would do it naturally. It does this without triggering stress hormones or other unwanted signals, which is why it became the most popular starting point in this entire space.

Use This If You're Trying To: Boost your growth hormone levels. This is the one most people start with because it works well and does not cause a lot of side effects.

CJC-1295

The Science: CJC-1295 is a synthetic analog of growth hormone releasing hormone (GHRH) engineered for extended half-life through albumin binding. The DAC version incorporates a lysine linker that covalently binds to circulating albumin, extending its activity from minutes to several days. It amplifies the size of GH pulses rather than their frequency, and is almost universally stacked with a GHRP like Ipamorelin to produce synergistic GH output.

Plain English: Your body makes a signal called GHRH that tells the pituitary to release growth hormone, but that signal disappears within minutes. CJC-1295 is a modified version that lasts days instead of minutes by hitching a ride on a protein in your blood. Stack it with Ipamorelin and you get a much bigger growth hormone response than either alone.

Use This If You're Trying To: Boost your growth hormone levels and keep them elevated longer. Almost nobody uses this alone. It gets paired with Ipamorelin because the two together work much better than either one by itself.

Sermorelin

The Science: Sermorelin is a 29-amino acid synthetic peptide representing the biologically active N-terminal fragment of endogenous GHRH. It acts on pituitary somatotrophs via the GHRH receptor, stimulating GH transcription and secretion. Because it preserves the pituitary's negative feedback sensitivity, it cannot produce supraphysiological GH levels, making it one of the safest compounds in this category. It was FDA-approved as a diagnostic agent and later as a GH deficiency treatment.

Plain English: Sermorelin is a shorter version of one of your body's natural growth hormone signals. It works within your body's normal controls, so it cannot push GH higher than your body allows. That makes it the gentlest and most conservative option in this class, and it actually has FDA approval behind it.

Use This If You're Trying To: Gently raise your growth hormone levels as you get older. This is the most conservative, beginner-friendly option in this group and the one most likely to be prescribed by an actual doctor.

GHRP-2

The Science: GHRP-2 is a synthetic hexapeptide that binds GHSR-1a with high affinity, producing robust GH release from the pituitary. Compared to Ipamorelin, it has a less selective receptor profile, producing moderate elevations in cortisol and prolactin alongside GH. It also stimulates ghrelin pathways, increasing appetite. It remains one of the most potent GHRPs for raw GH output and is used where maximum GH stimulation is the priority.

Plain English: GHRP-2 is like hitting the growth hormone button hard. It gets strong results but also triggers a few side effects you do not want, including higher stress hormone levels and increased hunger. It is more powerful than Ipamorelin but less clean.

Use This If You're Trying To: Push your growth hormone as high as possible and do not mind being hungrier or dealing with some stress hormone increase as a tradeoff.

GHRP-6

The Science: GHRP-6 is a hexapeptide GHSR agonist and one of the original growth hormone releasing peptides characterized in research. It produces strong GH release but is notable for significant ghrelin pathway activation, causing pronounced hunger and, at higher doses, elevated cortisol and prolactin. Its GH output per dose is strong but its side effect profile relative to newer GHRPs has made it less favored in current practice.

Plain English: GHRP-6 was one of the first peptides of this type that people widely used. It works, but it makes you very hungry and can raise stress hormones. Newer options have largely replaced it, though it still has a large body of anecdotal experience behind it from years of community use.

Use This If You're Trying To: Raise growth hormone and intentionally increase your appetite at the same time. Some people use this specifically when they are trying to eat more and gain weight.

Tesamorelin

The Science: Tesamorelin is a stabilized synthetic analog of GHRH consisting of the full 44-amino acid sequence conjugated to a trans-2-hexenoic acid group that improves metabolic stability. It is FDA-approved under the name Egrifta for the reduction of excess abdominal fat in HIV-associated lipodystrophy. Its mechanism is GHRH receptor activation, producing pulsatile GH release that secondarily reduces visceral adipose tissue via IGF-1 mediated lipolysis. It is arguably the most clinically validated GHRH analog available.

Plain English: Tesamorelin is a modified version of your body's growth hormone signal and one of the few compounds in this entire category that the FDA has approved as a real drug. It has been proven in clinical trials to reduce deep belly fat by boosting growth hormone levels in a natural, pulsatile way.

Use This If You're Trying To: Lose stubborn belly fat specifically, while also getting the benefits of higher growth hormone. One of the few in this group with actual FDA approval.

MK-677 (Ibutamoren)

The Science: MK-677 is a non-peptide, orally bioavailable ghrelin mimetic and GHSR-1a agonist. Unlike peptide GHRPs that require injection and have short half-lives, MK-677 is active orally with a half-life of approximately 24 hours, producing sustained elevation of both GH and IGF-1. Its ghrelin receptor activity also stimulates appetite and can increase cortisol and prolactin at higher doses. It is one of the most studied GH secretagogues in clinical trials, including for muscle wasting and GH deficiency in elderly populations.

Plain English: MK-677 is a pill that fools your body into thinking ghrelin (your hunger hormone) is elevated, which causes your pituitary to release more growth hormone throughout the day. The big appeal is that it is taken orally, not injected. The tradeoff is increased hunger and potential water retention.

Use This If You're Trying To: Raise growth hormone without needles. This is a pill. People also use it to sleep better and hold onto muscle. The main downsides are hunger and water retention.

IGF-1 LR3

The Science: IGF-1 LR3 is a recombinant analog of insulin-like growth factor 1 with a 13-amino acid N-terminal extension and an arginine substitution at position 3. These modifications reduce binding to IGF binding proteins (IGFBPs) in circulation, extending its half-life from minutes to approximately 20-30 hours and increasing its bioavailability at tissue receptor sites. It activates IGF-1 receptors systemically, promoting satellite cell proliferation, muscle protein synthesis, and tissue hypertrophy. It operates downstream of GH and can be used independently of GH axis manipulation.

Plain English: IGF-1 LR3 is a modified version of a growth signal your body naturally makes in response to growth hormone. The modification makes it last much longer in your body. Instead of working through growth hormone first, it goes directly to your muscles and tissues and tells them to grow and repair. It is one of the most anabolic compounds on this entire list.

Use This If You're Trying To: Build muscle and recover faster by going directly to the growth signal your muscles respond to, without needing to go through growth hormone first.

Follistatin 344

The Science: Follistatin 344 is an isoform of follistatin, an endogenous glycoprotein that functions as a binding protein and inhibitor of myostatin (GDF-8) and other TGF-beta superfamily members including activin and BMP ligands. By sequestering myostatin, follistatin removes a primary brake on skeletal muscle hypertrophy. Animal models have shown dramatic increases in muscle mass with follistatin overexpression. Human data is limited, but community use is driven by the well-validated myostatin inhibition mechanism.

Plain English: Your body produces a protein called myostatin whose entire job is to limit how much muscle you can grow. Follistatin blocks myostatin. When you remove that brake, the muscle-building process accelerates significantly. Animals with follistatin overexpression develop dramatically larger muscles, which is why it generates so much interest despite limited human research.

Use This If You're Trying To: Build significantly more muscle by removing one of your body's natural limits on how much muscle you can grow.

CATEGORY 2: GLP-1 AND METABOLIC

These compounds work primarily on appetite regulation, insulin secretion, and fat metabolism. The GLP-1 receptor agonists dominate this category and represent the biggest pharmaceutical story of the last decade.

Semaglutide

The Science: Semaglutide is a GLP-1 receptor agonist with 94% homology to native GLP-1, modified with a C18 fatty acid chain via a linker to enable albumin binding and extend its half-life to approximately 7 days. It reduces appetite via hypothalamic GLP-1 receptor activation, slows gastric emptying, and enhances glucose-dependent insulin secretion while suppressing glucagon. Clinical trials (STEP program) demonstrated 15-17% body weight reduction on average. It is FDA-approved as both Ozempic (diabetes) and Wegovy (obesity).

Plain English: Semaglutide is a once-weekly injection that mimics a hormone your gut releases after eating. It tells your brain you are full, slows down how fast food leaves your stomach, and helps your pancreas manage blood sugar. The result is significant, sustained weight loss. It is the drug behind Ozempic and became a cultural phenomenon when its weight loss effects became widely known.

Use This If You're Trying To: Lose weight. This is Ozempic. It makes you feel full faster, kills cravings, and produces real, significant weight loss for most people who use it.

Tirzepatide

The Science: Tirzepatide is a dual GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptor co-agonist. It is a synthetic 39-amino acid peptide with a C18 fatty diacid modification for albumin binding and weekly dosing. The addition of GIP receptor agonism adds complementary effects on adipose tissue, pancreatic beta cells, and potentially the central nervous system. SURMOUNT trials demonstrated average weight loss of 20-22%, outperforming semaglutide head-to-head in the SURMOUNT-5 trial.

Plain English: Tirzepatide does everything semaglutide does but adds a second gut hormone signal that targets a different receptor. Having two separate appetite and metabolism signals working together produces better weight loss results than targeting just one. In clinical trials it beat semaglutide for weight loss, which is why it quickly became the most sought-after drug in this space.

Use This If You're Trying To: Lose more weight than semaglutide gives you. This one targets two appetite signals instead of one and outperformed semaglutide in head-to-head trials.

Retatrutide

The Science: Retatrutide is a triple agonist targeting GLP-1, GIP, and glucagon receptors simultaneously. The addition of glucagon receptor agonism beyond the dual agonism of tirzepatide introduces direct effects on hepatic glucose output, thermogenesis, and fatty acid oxidation. Phase 2 trials showed average weight reduction of approximately 24% at 48 weeks, the highest of any pharmacological agent in this class to date. It remains in clinical development as of early 2025.

Plain English: Retatrutide adds a third signal on top of what tirzepatide does. That third signal (glucagon) tells your liver to burn fat directly and increases your metabolic rate. Early trial results showed more weight loss than any other drug in this class. It is not yet approved but has generated enormous anticipation in both clinical and community circles.

Use This If You're Trying To: Access the most powerful weight loss drug in this class. Currently only available through research channels or clinical trials, but watched closely by everyone in the metabolic space as the likely next step beyond tirzepatide.

Liraglutide

The Science: Liraglutide is a GLP-1 receptor agonist with 97% homology to native GLP-1, modified with a C16 fatty acid attached via a glutamic acid spacer. Its half-life is approximately 13 hours, necessitating daily injection. It was the first GLP-1 agonist approved for obesity (Saxenda) and demonstrated approximately 8% body weight reduction in trials. It has since been clinically superseded by longer-acting agents but remains the established pharmacological benchmark for the class.

Plain English: Liraglutide was the original version of the GLP-1 drug class that got approved for weight loss. It works the same basic way as semaglutide and tirzepatide but requires daily injections and produces somewhat less weight loss. It was a breakthrough when it arrived and is still prescribed today, though the newer weekly drugs have largely taken the spotlight.

Use This If You're Trying To: Use a daily version of the GLP-1 drugs instead of weekly. The older, daily option that paved the way for semaglutide. Works well but requires daily injections.

AOD-9604

The Science: AOD-9604 is a synthetic peptide fragment corresponding to amino acids 176-191 of the human growth hormone sequence, with the addition of a tyrosine residue at the N-terminus. Unlike full-length HGH, AOD-9604 does not bind the GH receptor or stimulate IGF-1 production. Its mechanism of fat reduction appears to involve direct stimulation of beta-3 adrenergic receptors in adipose tissue and inhibition of lipogenesis via pathways independent of insulin. It offers lipolytic effects without anabolic or insulin-sensitizing activity.

Plain English: Scientists isolated just the fat-burning region of the growth hormone molecule. AOD-9604 is that region, separated out. It does not affect blood sugar or muscle tissue; it only targets fat cells directly, which makes it theoretically useful without the systemic risks of full growth hormone.

Use This If You're Trying To: Burn body fat without affecting your hormones, blood sugar, or muscle tissue. It only targets fat cells.

Berberine

The Science: Berberine is an isoquinoline alkaloid that activates AMPK (AMP-activated protein kinase), the master energy-sensing enzyme of the cell. AMPK activation inhibits mTORC1 while simultaneously upregulating GLUT4 translocation to improve glucose uptake. It also reduces hepatic gluconeogenesis, modulates the gut microbiome toward short-chain fatty acid-producing species, and inhibits mitochondrial complex I. It demonstrates meaningful reductions in fasting glucose, HbA1c, and LDL in clinical trials and is frequently compared mechanistically to metformin.

Plain English: Berberine is a plant compound that activates one of your body's most important energy sensors, essentially a switch that tells your cells to handle fuel more efficiently. It helps your muscles take up blood sugar better, lowers your liver's sugar output, and improves your gut bacteria composition. People often call it "nature's metformin" because its effects are similar to that common diabetes drug.

Use This If You're Trying To: Improve blood sugar and metabolism with something you can buy without a prescription. People call it "nature's Ozempic" which is an overstatement, but it does work for blood sugar and cholesterol.

5-Amino-1MQ

The Science: 5-Amino-1-methylquinolinium (5-Amino-1MQ) is a small molecule inhibitor of nicotinamide N-methyltransferase (NNMT), an enzyme expressed primarily in adipose tissue and the liver that methylates nicotinamide and thereby depletes the available pool of SAM and NAD+. By inhibiting NNMT, 5-Amino-1MQ raises intracellular NAD+ and SAM levels, increasing metabolic rate in adipocytes and reducing lipid accumulation. In animal models it has demonstrated fat mass reduction without changes in food intake.

Plain English: There is an enzyme in fat tissue that acts as a metabolic brake by depleting a key energy molecule. 5-Amino-1MQ blocks that enzyme, which causes fat cells to burn more energy on their own and accumulate less fat. In animal studies, subjects lost fat without eating less. It is a small molecule but lives entirely within the peptide community because it is sold and discussed in the same channels.

Use This If You're Trying To: Speed up your metabolism at the cellular level, particularly inside fat cells. Often stacked with other metabolic compounds rather than used alone.

Tesofensine

The Science: Tesofensine is a triple monoamine reuptake inhibitor that blocks the reuptake of serotonin, dopamine, and norepinephrine in the presynaptic cleft. Originally developed for Parkinson's and Alzheimer's disease, its weight loss properties were discovered incidentally during those trials. It reduces appetite via central adrenergic and dopaminergic mechanisms and increases resting metabolic rate via sympathomimetic activity. Phase 2 trials showed approximately 10% body weight reduction over 24 weeks, with growing interest in combining it with GLP-1 agonists for additive effects.

Plain English: Tesofensine was originally being tested as a brain disease drug when researchers noticed people in the trials were losing significant weight. It works by keeping three key brain chemicals active longer than usual, which reduces appetite and speeds up metabolism simultaneously. It is now being explored both on its own and as an add-on to GLP-1 drugs to push weight loss even further.

Use This If You're Trying To: Reduce appetite and boost your metabolism through your brain chemistry rather than your gut hormones. Being explored as an add-on for people who have plateaued on GLP-1 drugs.

CATEGORY 3: STRUCTURAL AND TISSUE REPAIR

These peptides act locally and systemically to accelerate healing of connective tissue, gut mucosa, skin, and muscle. This category has the broadest community use for injury recovery and post-surgical healing.

BPC-157

The Science: BPC-157 (Body Protection Compound 157) is a synthetic 15-amino acid peptide derived from a sequence found in human gastric juice. It promotes angiogenesis via upregulation of VEGF and its receptors, accelerates tendon-to-bone healing through stimulation of tenocyte and fibroblast migration, modulates the nitric oxide system, and exhibits gastroprotective effects by maintaining mucosal integrity. It has demonstrated effectiveness across a wide range of tissue types in rodent models, including gut, tendon, muscle, bone, nerve, and vascular tissue.

Plain English: BPC-157 is a peptide fragment derived from a protein naturally found in your stomach. Researchers discovered it accelerates healing in essentially every tissue type they tested, including gut lining, tendons, muscles, and nerves. It does this partly by growing new blood vessels into injured areas and recruiting repair cells to the damage site. It remains a research compound but is arguably the single most discussed healing peptide in the world.

Use This If You're Trying To: Heal faster. Tendons, ligaments, muscles, gut lining, it does not matter much. This is the go-to for injury recovery and the most popular peptide in this entire category by a wide margin.

TB-500 (Thymosin Beta-4)

The Science: TB-500 is a synthetic version of the naturally occurring 43-amino acid peptide Thymosin Beta-4, or more accurately a fragment (Ac-SDKP) believed to carry much of its biological activity. TB4 is one of the most abundant peptides in mammalian cells and functions primarily as an actin-sequestering protein. It regulates actin polymerization, reduces inflammation, promotes cell migration, and stimulates angiogenesis. Its distribution through body fluids makes it effective for injuries distant from the administration site.

Plain English: TB-500 comes from a protein your body already makes in large quantities. Its main job involves controlling a structural protein called actin that every cell uses. When you are injured, TB-500 helps repair cells navigate to where they are needed, reduces inflammation, and helps build new blood vessels. Unlike some healing peptides that only work near the injection site, TB-500 travels through your whole body's fluids to reach distant injuries.

Use This If You're Trying To: Heal injuries throughout your whole body, not just at the spot you inject. Almost always used alongside BPC-157.

GHK-Cu

The Science: GHK-Cu (glycyl-L-histidyl-L-lysine copper complex) is a naturally occurring copper-binding tripeptide found in human plasma, urine, and saliva whose concentration declines significantly with age. It activates genes involved in collagen synthesis, DNA repair, anti-inflammatory response, and antioxidant activity. It promotes TGF-beta-mediated collagen and glycosaminoglycan synthesis, upregulates tissue inhibitors of metalloproteinases (TIMPs), and has demonstrated wound-healing and skin remodeling effects in clinical studies. It is effective both topically and systemically.

Plain English: GHK-Cu is a tiny three-amino acid peptide that naturally exists in your blood and skin, and its levels decline as you age. It acts as a repair signal, switching on genes involved in rebuilding collagen, healing wounds, and reducing inflammation. Applied to skin it improves texture and reduces visible aging. Injected systemically it has broader healing and anti-inflammatory effects throughout the body. The copper in its structure is essential to how it works.

Use This If You're Trying To: Improve your skin, reduce signs of aging, or support healing with something that has a very strong safety record. Works both in a cream and as an injection.

KPV

The Science: KPV is a tripeptide (Lysine-Proline-Valine) corresponding to the C-terminal sequence of alpha-MSH, which retains the parent peptide's anti-inflammatory activity without its melanogenic effects. It acts on melanocortin receptors (primarily MC1R and MC3R) expressed on immune cells and intestinal epithelium, downregulating NF-kB and reducing production of pro-inflammatory cytokines including TNF-alpha and IL-6. Its small size allows for oral delivery and localized gut action.

Plain English: KPV is a tiny three-amino acid fragment taken from one of your body's natural anti-inflammatory hormones. In your gut, it binds to receptors on immune and intestinal lining cells and tells them to calm down an overactive inflammatory response. Because it is so small, it can potentially be taken orally and act directly in the gut without being fully destroyed in digestion, which makes it particularly interesting for inflammatory bowel conditions.

Use This If You're Trying To: Calm down gut inflammation. Popular with people dealing with IBS, Crohn's, or leaky gut who want something that works directly in the digestive tract.

MGF (Mechano Growth Factor)

The Science: MGF is a splice variant of the IGF-1 gene produced locally in skeletal muscle in response to mechanical damage or stretch. Its unique N-terminal peptide (the MGF E-domain) activates a distinct receptor from the classic IGF-1 receptor, promoting satellite cell activation and proliferation. This is the critical initial step in muscle repair: satellite cells are muscle stem cells that must be recruited before regeneration can proceed. MGF sits upstream of the repair cascade and is distinct from systemic IGF-1 in its local, transient expression pattern.

Plain English: When you damage a muscle, your body produces a special local signal called MGF that wakes up the muscle's own repair cells (satellite cells). These satellite cells are dormant stem cells sitting in your muscle tissue, and MGF is what gets them activated and moving toward the damage site. Without satellite cell activation, proper muscle repair cannot begin. MGF specifically targets that first step, making it most relevant immediately after injury or intense training.

Use This If You're Trying To: Speed up muscle repair right after a hard training session or injury. It specifically activates the repair process in the first hours after damage occurs.

CATEGORY 4: MITOCHONDRIAL AND REDOX

These compounds target the mitochondria directly or support cellular antioxidant systems. This is the fastest-growing research frontier on this list and contains some of the least clinically available but most scientifically compelling compounds.

SS-31 (Elamipretide)

The Science: SS-31 (D-Arg-Dmt-Lys-Phe-NH2) is an aromatic-cationic tetrapeptide that selectively concentrates at the inner mitochondrial membrane by binding cardiolipin, a phospholipid essential for inner mitochondrial membrane structural integrity and electron transport chain organization. By stabilizing cardiolipin-cytochrome c interactions, SS-31 improves electron transport chain efficiency, reduces electron leak and superoxide production, and restores mitochondrial membrane potential. It has completed Phase 2 trials for mitochondrial myopathy and shown striking results in heart failure and ischemia-reperfusion models.

Plain English: SS-31 is a small peptide that travels directly to the powerhouses of your cells (mitochondria) and sticks to a critical structural fat molecule on the inner membrane. When that membrane is damaged by aging or disease, energy production becomes inefficient and leaks damaging free radicals. SS-31 stabilizes that membrane, making energy production cleaner and more efficient. It has shown remarkable results in clinical trials for heart disease and muscle-wasting conditions.

Use This If You're Trying To: Fix low energy at the cellular level. If you are tired in a way that sleep does not fix, this targets the actual machinery inside your cells that produces energy.

MOTS-c

The Science: MOTS-c is a 16-amino acid peptide encoded within the mitochondrial 12S rRNA gene, making it one of a small class of mitochondria-derived peptides with hormonal functions. It translocates to the nucleus under metabolic stress, where it activates AMPK and regulates gene expression related to glucose and fatty acid metabolism. It improves insulin sensitivity, increases exercise capacity, and extends lifespan in animal models. Circulating levels decline with age, suggesting a role in metabolic aging.

Plain English: MOTS-c is a hormone-like peptide that comes directly from your mitochondria, which is unusual because most hormones are made elsewhere. When your cells are under metabolic stress, MOTS-c travels to the cell nucleus and switches on genes that improve how your body handles blood sugar and burns fat. It essentially mimics some of the metabolic benefits of exercise, and its levels naturally drop as you get older, which may be one reason metabolism slows with age.

Use This If You're Trying To: Get some of the metabolic benefits of exercise, improve how your body handles blood sugar, and support healthy aging at the cellular level.

Humanin

The Science: Humanin is a 21-amino acid peptide encoded in the mitochondrial 16S rRNA region. It binds to a tripartite receptor complex including gp130, CNTFR, and WSX-1 and activates STAT3 and MAPK pathways to produce cytoprotective and anti-apoptotic effects. It protects neurons against amyloid-beta toxicity, reduces insulin resistance, decreases systemic inflammation, and its circulating levels correlate inversely with age and age-related disease. Offspring of centenarians have been found to have measurably higher circulating humanin levels.

Plain English: Humanin is a small peptide that your mitochondria produce as a cellular survival signal. It protects neurons from damage, keeps inflammation low, and helps your body manage blood sugar. Your body naturally produces less of it as you age, and people who live to 100 (or whose parents did) tend to have higher levels. Researchers believe it may be one of the molecular reasons some people age better than others.

Use This If You're Trying To: Protect your brain, reduce inflammation, and support the kind of cellular resilience associated with people who live longer and healthier lives.

NAD+ (and precursors: NMN, NR)

The Science: NAD+ (nicotinamide adenine dinucleotide) is an essential coenzyme involved in redox reactions across the electron transport chain, as a substrate for sirtuins (SIRT1-7) which regulate gene expression, DNA repair, and metabolic homeostasis, and for PARPs involved in DNA damage response. NAD+ levels decline approximately 50% between age 40 and 60. Supplementation with precursors NMN or NR raises tissue NAD+ levels and has demonstrated benefits in animal aging models, with promising signals in human trials for muscle function and cardiovascular markers.

Plain English: NAD+ is a molecule your cells absolutely require to produce energy and repair DNA damage. Your levels drop dramatically as you age, which many researchers believe contributes to the aging process itself. You cannot absorb NAD+ well as a direct supplement, so people take precursors (NMN or NR) that the body converts into NAD+. Raising NAD+ levels has extended lifespan in animal studies and shown early positive results in humans.

Use This If You're Trying To: Slow down the energy decline that comes with aging. NAD+ is something your body makes less of every decade and supplementing it is one of the most common starting points in longevity protocols.

MitoQ

The Science: MitoQ (mitoquinol mesylate) is a mitochondria-targeted antioxidant consisting of the ubiquinone (CoQ10) moiety linked to a triphenylphosphonium (TPP+) cation. The TPP+ cation exploits the large negative mitochondrial membrane potential to accumulate within the mitochondrial matrix at concentrations several hundredfold higher than in the cytoplasm. Once there, MitoQ cycles between its reduced ubiquinol (antioxidant-active) form and its oxidized form, neutralizing superoxide and preventing lipid peroxidation at the primary site of free radical generation.

Plain English: Regular CoQ10 supplements barely reach the mitochondria where they are actually needed. MitoQ is CoQ10 chemically attached to a positively charged molecule that acts like a magnet, pulled into the mitochondria by the electrical charge on the mitochondrial membrane. Once inside, it accumulates at concentrations hundreds of times higher than a regular supplement and acts as a powerful antioxidant exactly where free radicals are being generated.

Use This If You're Trying To: Get the benefits of CoQ10 but in a form that actually reaches your mitochondria instead of mostly passing through your body unused.

Urolithin A

The Science: Urolithin A is a gut microbiome-derived metabolite produced from ellagic acid (found in pomegranates, walnuts, and berries) by specific bacterial species. It is the only known natural compound that robustly induces mitophagy, the selective autophagy of damaged mitochondria. By clearing dysfunctional mitochondria it improves mitochondrial quality control and biogenesis. Human trials have demonstrated improvements in muscle endurance and mitochondrial biomarkers in older adults, and its production varies significantly between individuals based on gut microbiome composition.

Plain English: Urolithin A is a compound your gut bacteria make from certain plant foods, but most people's gut bacteria cannot produce it efficiently. It performs a specific and important function: it tells your cells to clear out old, broken mitochondria and replace them with new ones. This process (called mitophagy) is essential for maintaining muscle and cellular health as you age. Clinical trials in older adults have shown measurable muscle function improvements with direct supplementation.

Use This If You're Trying To: Help your body clean out old, worn-down mitochondria and replace them with fresh ones. This keeps your muscles and cells working better as you age, and it actually has human clinical trial data behind it.

Glutathione

The Science: Glutathione (GSH) is a tripeptide (gamma-glutamylcysteinylglycine) and the most abundant intracellular antioxidant in mammalian cells, maintained at concentrations of 1-10 mM in the cytoplasm. It neutralizes reactive oxygen species directly, serves as a cofactor for glutathione peroxidases, supports phase II xenobiotic detoxification in the liver, and regenerates vitamins C and E. Intracellular GSH depletion is a hallmark of oxidative stress and aging. Oral bioavailability is limited by intestinal degradation, driving use of liposomal and IV forms, as well as precursor supplementation with N-acetylcysteine and glycine.

Plain English: Glutathione is your body's master antioxidant and every cell produces it constantly to neutralize the damaging byproducts of normal metabolism. It also helps your liver detox chemicals and recycles other antioxidants like vitamin C. Levels drop with age, chronic illness, and toxic exposure. Because a regular oral supplement is poorly absorbed (your gut breaks it apart before it reaches circulation), people use liposomal or IV delivery to actually raise tissue levels.

Use This If You're Trying To: Reduce oxidative stress, support your liver, or recover from something that has depleted your body's natural defenses like illness, heavy drinking, intense training, or toxic exposure.

CATEGORY 5: NEUROTROPIC AND COGNITIVE

These compounds enhance brain-derived neurotrophic factor, stimulate neuroplasticity, provide neuroprotection, or modulate neurotransmitter systems. Many originate from Russian and Eastern European pharmaceutical research.

Semax

The Science: Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) derived from the ACTH(4-7) sequence, with a Pro-Gly-Pro extension that improves metabolic stability. It does not activate adrenal or melanocortin pathways at therapeutic doses. Its primary mechanism involves upregulation of BDNF and NGF synthesis, particularly in the hippocampus and prefrontal cortex. It also modulates dopaminergic and serotonergic tone and demonstrates neuroprotective effects in ischemia models. It was developed in Russia in the 1980s and is approved there for stroke recovery.

Plain English: Semax is a modified peptide fragment originally taken from a stress hormone, but with the stress-inducing effects removed. It increases production of BDNF, a protein often described as fertilizer for brain cells, which supports the growth and survival of neurons. People report improvements in focus, mental clarity, and stress resilience. It is delivered as a nasal spray, approved as a medicine in Russia, and widely used in biohacking communities in the West.

Use This If You're Trying To: Think more clearly, focus better, and feel less mentally drained. It does this by helping your brain grow and maintain healthy neurons, not by stimulating you like caffeine.

Selank

The Science: Selank is a synthetic heptapeptide analog of the endogenous immunomodulatory tetrapeptide tuftsin, with a Pro-Gly-Pro stabilizing extension. Its anxiolytic effects appear to involve GABAergic modulation without direct GABA-A receptor binding, resulting in anxiolysis without sedation, dependence, or withdrawal. It also upregulates BDNF, modulates brain enkephalin levels, and has demonstrated antidepressant and nootropic properties in Russian clinical studies.

Plain English: Selank is the calming counterpart to Semax, also from Russian pharmaceutical research. It relieves anxiety and promotes mental clarity but unlike common anti-anxiety drugs, it does not cause sedation, dependency, or withdrawal. It appears to interact with the brain's calming systems in an indirect way that smooths out anxiety without blunting cognition. Most users describe a state of calm focus rather than sedation.

Use This If You're Trying To: Take the edge off anxiety without getting sedated or dependent. People describe it as quieting mental noise while keeping your thinking sharp.

Dihexa

The Science: Dihexa (N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) is a small, orally active peptide analog of angiotensin IV developed at Washington State University. It potentiates HGF (hepatocyte growth factor) signaling through its receptor c-Met, driving synaptogenesis and dendritic arborization. In animal models it reversed cognitive deficits with a potency estimated to be several million times greater than BDNF by molar concentration. It appears to act by driving the formation of new synaptic connections in existing neural circuits rather than replacing lost neurons.

Plain English: Dihexa is a small peptide that appears to be extraordinarily potent at growing new connections between brain cells. It works by activating a growth factor receptor that stimulates the brain to build new synapses, which are the connection points between neurons where learning and memory happen. Animal studies have reversed significant cognitive decline with tiny doses, which is why it has attracted intense community interest despite having no human clinical trials yet.

Use This If You're Trying To: Seriously improve memory and cognitive function, particularly if you feel like your mental sharpness has declined. Very potent in animal studies but no human trials yet.

Cerebrolysin

The Science: Cerebrolysin is a standardized mixture of low-molecular-weight neuropeptides and amino acids derived from purified porcine brain tissue via controlled enzymatic hydrolysis. Its small peptide fragments cross the blood-brain barrier and mimic the actions of NGF, BDNF, and other endogenous neurotrophins. Its mechanisms include upregulation of neurotrophin expression, reduction of amyloid precursor protein processing, protection against glutamate-mediated excitotoxicity, and promotion of neuronal survival and differentiation. It has clinical evidence supporting use in stroke recovery, Alzheimer's disease, and traumatic brain injury in European and Asian medical practice.

Plain English: Cerebrolysin is an injectable mixture of small peptide fragments derived from pig brain tissue. Those fragments cross into the brain and mimic the effects of natural growth factors that keep neurons alive, healthy, and forming new connections. It has been used clinically in Europe and Asia for decades in stroke recovery and dementia. Think of it as delivering a complex cocktail of brain growth signals in a form the nervous system can use directly.

Use This If You're Trying To: Support recovery from a brain injury, stroke, or significant cognitive decline. More of a clinical-level intervention than a general nootropic.

P21

The Science: P21 is a synthetic peptide analog of CNTF (ciliary neurotrophic factor) designed to bypass the pro-inflammatory Jak-STAT signaling that limits CNTF's clinical utility. It activates neurogenesis in the hippocampal dentate gyrus, a region critical for learning and memory formation and one of the few areas of the adult brain where new neurons continue to be generated. It increases doublecortin expression (a marker of new neurons) and has shown spatial memory improvements in rodent models.

Plain English: P21 is a peptide designed to stimulate the growth of new neurons in the hippocampus, the brain region most important for forming new memories. Most parts of your brain cannot generate new neurons after childhood, but the hippocampus is an exception. P21 appears to activate that process. Animal studies show memory improvements, and it has attracted significant interest for age-related cognitive decline, though human studies have not yet been conducted.

Use This If You're Trying To: Specifically support memory formation and learning by stimulating your brain to grow new neurons in the memory center. Still early stage with no human data.

Noopept

The Science: Noopept (N-phenylacetyl-L-prolylglycine ethyl ester) is a synthetic dipeptide nootropic and prodrug for cycloprolylglycine, a naturally occurring neuropeptide. Following oral ingestion and hydrolysis, it crosses the blood-brain barrier and modulates AMPA and NMDA glutamate receptors, enhancing synaptic plasticity. It also upregulates NGF and BDNF expression in the hippocampus and cortex. Developed in Russia, it has demonstrated improvements in cognition and anxiety in clinical trials at doses far lower than piracetam, to which it is often compared.

Plain English: Noopept is one of the most popular brain supplements in the world, originating from Russian research as a more potent alternative to piracetam (the original smart drug). It is a small peptide that your body converts into a compound that enhances the sensitivity of glutamate receptors, which are central to learning and memory. It also increases production of brain growth factors. Taken orally, it works at very low doses, and is the most discussed nootropic compound on Reddit and supplement forums globally.

Use This If You're Trying To: Sharpen your thinking and memory with something you take orally, at a very low dose, that has more community documentation behind it than almost anything else in this category.

DSIP (Delta Sleep-Inducing Peptide)

The Science: DSIP is a neuropeptide originally isolated from rabbit cerebral venous blood during slow-wave sleep induction experiments. It modulates sleep architecture by promoting delta wave (slow-wave) sleep and suppressing REM fragmentation. Beyond sleep, it has demonstrated stress-protective and antioxidant effects and regulates pituitary hormone secretion including GH, LH, and corticotropin. Its mechanism involves modulation of glutamate and opioid receptors as well as direct hypothalamic effects. Human study results have been variable and its pharmacology remains incompletely characterized.

Plain English: DSIP was discovered by studying the brains of sleeping rabbits and appears to promote the deepest, most restorative stage of sleep while also having calming and stress-reducing effects. It also interacts with hormone-releasing systems in the brain. Human research shows mixed results, which keeps it in the interesting-but-unproven category, though consistent anecdotal reports of improved sleep quality drive ongoing community interest.

Use This If You're Trying To: Get deeper, more restorative sleep. Specifically targets the deep sleep stage that is most important for physical recovery and hormone release.

CATEGORY 6: IMMUNE AND LONGEVITY

These compounds modulate immune function, support thymic output, target telomere dynamics, or act on systems that appear to regulate biological aging rate.

Thymosin Alpha-1 (TA-1)

The Science: Thymosin Alpha-1 is a 28-amino acid peptide naturally secreted by thymic epithelial cells that serves as a key regulator of T-cell maturation and immune competence. It promotes differentiation of T-cell progenitors, enhances dendritic cell function, upregulates MHC class I expression on tumor cells (increasing their visibility to cytotoxic T cells), and drives a Th1-dominant immune response. It is FDA-approved under the name Zadaxin for hepatitis B and C and is used clinically across Asia and Europe for cancer support, sepsis, and immune restoration.

Plain English: Your thymus gland produces signals that train your immune cells to function properly. TA-1 is one of the most important of those signals. It helps immature immune cells develop into effective defenders, improves the immune system's ability to recognize cancer cells, and shifts the immune response toward fighting viruses and tumors more aggressively. It is an approved drug in many countries with a meaningful body of clinical evidence behind it.

Use This If You're Trying To: Strengthen your immune system, particularly if you have a chronic infection, are recovering from illness, or feel like your immune system is underperforming. Has actual clinical approval in many countries.

Thymalin

The Science: Thymalin is a polypeptide complex extracted from bovine thymus glands, containing multiple bioactive peptide fractions. Developed in the Soviet Union by Vladimir Khavinson as part of a broader program of organ-specific peptide bioregulators, it restores thymic function and T-cell populations in aged or immunocompromised individuals, corrects neuroendocrine imbalances associated with thymic involution, and in human longevity studies conducted over decades, its use was associated with significant reductions in mortality in elderly subjects.

Plain English: Thymalin is an extract from thymus glands containing a mixture of the signaling peptides that tissue naturally produces. It was developed in Russia as part of a long-running program using organ-specific peptides to restore aging organ function. In human studies spanning decades, elderly people who received Thymalin cycles had measurably lower death rates than controls. The concept is partial restoration of the thymus's ability to maintain immune competence that declines with age.

Use This If You're Trying To: Restore immune function that has declined with age and reduce the long-term health risks that come with a weakening immune system.

Epithalon

The Science: Epithalon (Ala-Glu-Asp-Gly) is a synthetic tetrapeptide analog of epithalamin, a natural polypeptide produced by the pineal gland. Its most studied mechanism is induction of telomerase activity in somatic cells, theoretically decelerating telomere shortening. It also restores melatonin secretion in aged pineal gland tissue, regulates the hypothalamic-pituitary axis, and has demonstrated antioxidant, anti-tumor, and life-extension properties in animal studies. Khavinson's research group has published the most extensive body of work on it, including some human data suggesting improved biomarkers of aging.

Plain English: Epithalon is a four-amino acid peptide derived from research on the pineal gland. Its most discussed mechanism is activating telomerase, an enzyme that rebuilds the protective caps on your chromosomes that shorten every time your cells divide. Shorter telomeres are associated with cellular aging. It has also been shown to restore melatonin production in older animals. It is the most discussed longevity peptide in the biohacking community and the subject of more published research than almost anything else in this category.

Use This If You're Trying To: Slow down aging at the cellular level. This is the most popular longevity peptide in the biohacking community and the most discussed compound in this entire category.

VIP (Vasoactive Intestinal Peptide)

The Science: VIP is a 28-amino acid neuropeptide synthesized throughout the central and peripheral nervous systems as well as immune cells. It acts on VPAC1 and VPAC2 receptors to produce smooth muscle relaxation (vasodilation, bronchodilation), regulation of circadian rhythms via the suprachiasmatic nucleus, and potent anti-inflammatory effects via suppression of TNF-alpha, IL-6, and IL-12 while promoting regulatory T-cell differentiation. In the Shoemaker biotoxin illness protocol, VIP is used as a final-stage treatment to normalize neurological and inflammatory dysregulation in chronic inflammatory response syndrome (CIRS).

Plain English: VIP is a neuropeptide that your nervous system and immune cells both produce. It relaxes blood vessels and airways, helps regulate your body clock, and powerfully calms excessive immune responses. It has become particularly prominent in communities focused on chronic illness related to mold or biotoxin exposure, where it is used to help normalize a dysregulated immune and nervous system. It sits at an unusual intersection of immune regulation, neurology, and chronic illness treatment.

Use This If You're Trying To: Address chronic inflammation that has not responded to other approaches, particularly if it is connected to mold exposure, chronic illness, or a dysregulated immune system.

LL-37

The Science: LL-37 is a 37-amino acid cathelicidin-derived antimicrobial peptide, the only human cathelicidin, cleaved from the hCAP18 precursor by serine proteases in neutrophils and epithelial cells. It kills a broad spectrum of bacteria, fungi, and enveloped viruses via direct membrane disruption and also functions as an immunomodulatory signaling molecule. It promotes wound healing through chemoattraction of immune cells, stimulates angiogenesis, and modulates toll-like receptor signaling. It is dysregulated in multiple conditions including rosacea (overexpressed) and atopic dermatitis (underexpressed).

Plain English: LL-37 is your body's own naturally produced antibiotic peptide, one of the frontline defenders your immune cells release to kill bacteria, fungi, and viruses by punching holes in their membranes. Beyond killing pathogens, it also signals wound-healing and immune cells to mobilize and helps build new blood vessels in healing tissue. Interest in the peptide community focuses on its potential for wound healing, skin conditions, and antibiotic-resistant infections where conventional antibiotics have failed.

Use This If You're Trying To: Fight infections that are hard to treat, support wound healing, or strengthen the part of your immune system that responds first to threats.

CATEGORY 7: SEXUAL HEALTH AND MELANOCORTIN

These compounds act on the melanocortin system or related hormonal pathways to influence libido, arousal, skin pigmentation, and sexual function through central nervous system mechanisms.

PT-141 (Bremelanotide)

The Science: PT-141 is a cyclic heptapeptide melanocortin receptor agonist with activity at MC1R, MC3R, MC4R, and MC5R. Unlike phosphodiesterase inhibitors that work peripherally through vascular mechanisms, PT-141 activates MC4R in the hypothalamus to increase dopaminergic firing in the mesolimbic pathway, producing central arousal and libido enhancement. It is FDA-approved as Vyleesi for hypoactive sexual desire disorder (HSDD) in premenopausal women. Its mechanism is entirely central, meaning it works in the brain rather than the genitals.

Plain English: Most arousal drugs work by increasing blood flow to sexual organs. PT-141 is completely different: it works in the brain by activating dopamine pathways that generate sexual desire and motivation. It was FDA-approved to treat low sexual desire in women, which is notable because almost no drugs exist for that indication. Men use it off-label as well. Rather than addressing a mechanical issue, it actually increases the desire and drive for sex at the neurological level.

Use This If You're Trying To: Increase your desire for sex, not just the physical mechanics of it. This works in your brain on the want-to, not in your body on the can.

Melanotan II

The Science: Melanotan II (MT-II) is a cyclic synthetic analog of alpha-MSH with non-selective binding across melanocortin receptors (MC1R-MC5R). MC1R activation produces melanogenesis by stimulating melanocyte production of eumelanin. MC4R activation produces the central libido-enhancing and appetite-suppressing effects. MT-II is the precursor from which PT-141 was derived: researchers noticed profound libido effects incidentally during tanning research and developed PT-141 specifically to isolate the MC4R-mediated sexual effects while reducing melanogenic activity.

Plain English: Melanotan II was originally studied as a way to produce a tan without sun exposure, by activating the cells that make skin pigment. Researchers testing it noticed unexpectedly strong sexual arousal as a side effect and realized it was also activating a different receptor in the brain. That discovery eventually led to the development of PT-141 as a dedicated libido drug. MT-II itself is still widely used for both purposes and is not FDA-approved, carrying more side effects than PT-141 including nausea and spontaneous erections.

Use This If You're Trying To: Get both a tan and a libido boost from a single compound. Carries more side effects than PT-141 and is not FDA approved.

Oxytocin

The Science: Oxytocin is a 9-amino acid nonapeptide produced in the hypothalamic paraventricular and supraoptic nuclei and released from the posterior pituitary. It acts on oxytocin receptors distributed throughout the brain, reproductive organs, and cardiovascular system. It mediates uterine contraction, milk ejection, pair bonding, trust, and social recognition, and modulates amygdala reactivity to reduce fear and social threat perception. In sexual contexts it is released during orgasm in both sexes and amplifies the affiliative and arousal components of intimate experience. Intranasal delivery bypasses systemic clearance to achieve CNS concentrations.

Plain English: Oxytocin is often called the bonding or love hormone because your brain releases it during hugging, intimacy, and orgasm. It creates feelings of trust, connection, and attachment. Intranasal oxytocin (delivered through the nose to reach the brain more directly) is used in communities focused on relationship intimacy, social anxiety reduction, and enhancing the emotional quality of sexual and social experiences. It does not increase physical arousal the way PT-141 does but rather enhances the emotional bonding and pleasure dimensions of connection.

Use This If You're Trying To: Feel more emotionally connected during intimacy, reduce social anxiety, or enhance the bonding experience in relationships. This is not about physical arousal, it is about emotional depth and connection.

Kisspeptin-10

The Science: Kisspeptin-10 is the shortest bioactive fragment of the kisspeptin family of neuropeptides encoded by the KISS1 gene. It acts on GPR54 (KISS1R) receptors in the hypothalamus to stimulate pulsatile GnRH secretion, which drives LH and FSH release from the pituitary, making it the master upstream regulator of the reproductive hormone axis. Kisspeptin neurons integrate signals from estrogen, testosterone, leptin, and metabolic status to calibrate GnRH output. It has been investigated clinically for infertility treatment and for restoring LH pulsatility and endogenous testosterone production in males.

Plain English: Kisspeptin sits at the very top of the hormone cascade that controls reproductive function in both men and women. It sends a signal that triggers GnRH release, which then triggers LH and FSH, which then control testosterone and estrogen production. It is the upstream master switch of your sex hormone system. Researchers are exploring it as a treatment for infertility and low testosterone because it works with the body's own hormonal control architecture rather than bypassing it.

Use This If You're Trying To: Support your body's own natural testosterone or estrogen production by working at the very top of the hormonal chain rather than replacing hormones directly.

CATEGORY 8: NUCLEAR RECEPTOR AND ENDURANCE

These small molecules activate nuclear receptors or metabolic sensors that regulate mitochondrial biogenesis, fatty acid oxidation, and exercise adaptation. None are technically peptides but they live entirely within this community.

Cardarine (GW501516)

The Science: Cardarine is a PPARdelta agonist that upregulates genes involved in fatty acid oxidation, mitochondrial biogenesis, and glucose sparing in skeletal muscle. It shifts fuel utilization toward fat oxidation even at high exercise intensities, dramatically enhancing endurance capacity in animal models. It also raises HDL and reduces LDL, triglycerides, and insulin resistance. Development was abandoned by GlaxoSmithKline after carcinogenicity findings in long-term rodent studies.

Plain English: Cardarine activates a switch in muscle cells that tells them to burn fat for fuel even during intense exercise, instead of switching to carbohydrates as muscles normally do at higher intensities. This dramatically increases endurance because fat stores are essentially unlimited while carbohydrate stores are not. In animal studies it turned sedentary mice into exceptional endurance performers. The reason it was never approved as a drug is that long-term animal studies found it accelerated cancer growth, which caused the pharmaceutical company to stop development entirely.

Use This If You're Trying To: Dramatically improve your endurance and your body's ability to burn fat during exercise. Be aware that this one has serious unresolved cancer concerns from animal studies that have never been fully answered.

SR9009 (Stenabolic)

The Science: SR9009 is a synthetic Rev-erb alpha and Rev-erb beta agonist. Rev-erb proteins are nuclear receptors that function as core components of the circadian clock and regulate transcription of genes involved in lipid and glucose metabolism, mitochondrial biogenesis, and inflammatory response. Activation of Rev-erb suppresses BMAL1 expression, reducing gluconeogenesis, lipogenesis, and inflammation while increasing mitochondrial content in skeletal muscle. In animal studies it increased exercise capacity and reduced obesity even in sedentary animals. Its oral bioavailability in humans remains actively debated.

Plain English: SR9009 targets proteins that control your body's internal clock and are deeply connected to how your cells decide when to burn fat or store it. By activating these proteins, it pushes metabolism toward fat burning and mitochondria building throughout the day. Animal studies showed significant endurance improvements and fat loss even without exercise. Whether it works the same way orally in humans is debated, which has not stopped its widespread community use.

Use This If You're Trying To: Burn fat and improve endurance without the cancer concerns attached to Cardarine. Whether it actually works well orally in humans is still debated.

AICAR

The Science: AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide) is a cell-permeable analog of AMP that activates AMPK by mimicking the cellular low-energy state. AMPK activation inhibits anabolic processes while upregulating fatty acid oxidation, glucose uptake via GLUT4 translocation, and mitochondrial biogenesis via PGC-1alpha upregulation. It was notably found on WADA's banned substance list after research demonstrated it could increase running endurance in sedentary mice without training.

Plain English: AICAR fools your cells into thinking they are low on energy, which activates a master energy-sensing molecule called AMPK. When AMPK switches on, your cells start burning fat, building more mitochondria, and pulling sugar from the blood more efficiently. Essentially the metabolic things that happen during exercise happen inside your cells even without physical activity. WADA banned it in competitive sports after studies showed it could significantly improve endurance in animals that did not exercise at all.

Use This If You're Trying To: Trigger the same kind of metabolic adaptations your body makes in response to endurance training, even when you are not training. WADA banned it in sport for exactly that reason.

SLU-PP-332

The Science: SLU-PP-332 is a synthetic agonist of estrogen-related receptors alpha, beta, and gamma (ERRalpha, ERRbeta, ERRgamma), a class of orphan nuclear receptors that regulate mitochondrial biogenesis, oxidative metabolism, and energy homeostasis in skeletal muscle and cardiac tissue. Unlike PPARdelta agonists, ERR agonism specifically increases the proportion of slow-twitch, fatigue-resistant type I muscle fibers and dramatically upregulates genes of the electron transport chain. In rodent studies published in 2023, it increased treadmill endurance by approximately 70% in untrained mice.

Plain English: SLU-PP-332 is one of the newest and most talked-about compounds in this space. It activates a set of receptors in muscle cells that instruct them to convert toward the slow-twitch, endurance-optimized fiber type and build more mitochondria. In mouse studies from 2023, untrained animals given SLU-PP-332 ran approximately 70% further than untrained controls with no additional exercise. It represents a genuinely novel mechanism compared to older endurance compounds and is currently generating significant research and community interest.

Use This If You're Trying To: Access the newest and most talked-about endurance compound in the space. A 2023 study showed it increased running endurance by about 70% in untrained animals. Human data does not exist yet but the interest is enormous.