What Are Peptides? Types, How They Work and What the Science Actually Says
A plain English guide to what peptides are, what they do and why the evidence matters.
Blog · Explainers · Research
Peptide science,
Peptide science,
without the noise
Deep dives into the peptides people are searching for, the studies behind them, and the difference between promising research and established evidence.
Start here
Popular explainers
-
01
Retatrutide Explained: How the Triple Agonist Works and What the Latest Research Shows
Retatrutide may be the most talked about weight management drug you cannot currently be prescribed. It is also a good example of why promising, proven and approved are three different words.
-
02
BPC-157: What Does the Human Evidence Actually Show?
BPC-157 is not a compound without research. It is a compound with a great deal of one kind of research, in animals, and very little of the kind that matters most, in people.
-
03
Semaglutide vs Tirzepatide vs Retatrutide: What's the Difference?
The three are often described as three generations of the same drug. That is handy shorthand, but it is not quite right. They act on different combinations of receptors, and the evidence behind them is very different in kind.
-
04
GHK-Cu / Copper Peptides: What Do They Actually Do for Skin and Hair?
Copper peptides sound like something from a laboratory rather than a bathroom cabinet, but the idea is simple: bind copper to a small peptide and see whether it changes how cells behave. The honest answer depends on whether you mean an interesting ingredient, a tested formula or a proven treatment.
Latest
All posts, newest first
Can You Mix Peptides in One Syringe? Compatibility, Stability and What Never to Combine
Why combining two different peptides in one syringe can alter or destroy the compounds.
BPC-157 and Thymosin Beta-4: Why They Are Stacked for Repair
How two distinct repair mechanisms are combined in experimental tissue recovery.
Why CJC-1295 and Ipamorelin Are Stacked: GHRH and GHRP Synergy
Why targeting two separate pituitary receptors produces a synergistic growth hormone response.
How GHK-Cu Repairs Crow's Feet: What the Skin Studies Show
How a naturally occurring copper peptide rebuilds the thin skin around the eyes.
Peptide Overload: Can Peptides Shut Down Your Own Hormones, and Where Kisspeptin Fits
Why continuous peptide stimulation can shut down your hormones, and what the human kisspeptin data actually shows.
How to Release Natural HGH With Peptides
How GHRH analogues and ghrelin mimetics make the pituitary release its own growth hormone.
Peptide Dosage Guide: Doses From Human Studies
The doses used in published human trials.
Peptide Pharmacokinetics vs Pharmacodynamics Explained
Blood concentration and biological response are different pieces of peptide evidence.
Peptide Stacking: What Works With What and Why
Why researchers combine peptides and where the clinical evidence stops.
Follistatin Explained: Myostatin Inhibition and Peptide Reality
Why the biological mechanism of follistatin does not support the use of black market injectable peptides.
P21 (P021) Peptide Explained: What Does the Preclinical Evidence Actually Show?
Clarifying the origins of P21 and objectively reviewing the rodent data on neurogenesis.
MGF Explained: What Does the Evidence on Mechano Growth Factor Actually Show?
Separating the natural muscle repair biology of IGF-1Ec from the unproven synthetic peptide.
IGF-1 LR3 vs IGF-1 DES: What's the Difference and What Does the Evidence Actually Show?
How structural changes create two very different IGF-1 analogues.
ARA-290 Explained: What Do the Human Trials in Neuropathy Actually Show?
What the phase 2 human trials actually reveal about ARA-290 and nerve repair.
Cerebrolysin Explained: What Do the Human Trials in Stroke and Dementia Actually Show?
What the human clinical data actually says about the widely discussed brain peptide mixture.
Dihexa Peptide Explained: What Is It and What Does the Research Actually Show?
Why this experimental compound lacks the human evidence to support its cognitive claims.
Peptide Evidence Explained: In Vitro, Animal and Human Studies
Learn what different peptide studies can prove, and what they cannot.
Oral Peptides Explained: Why Most Peptides Are Hard to Turn Into Tablets
Why peptide tablets are difficult, and what oral semaglutide teaches us about solving the problem.
Peptide Half Life Explained: Why Some Last Minutes and Others Days
Why one peptide disappears in minutes while another remains in circulation for days.
Elamipretide (SS-31): What Does FDA Approval Actually Mean?
FDA approval is real, but it applies to one rare disease and a very specific evidence base.
How to Reconstitute Peptides: What the Process Involves and Where It Goes Wrong
Reconstitution is simple in concept, but product specific stability and sterility rules are where mistakes begin.
Mazdutide Explained: What Human Trials Show in 2026
Phase 3 data are strong, but the newest US trial adds important context.
Peptide Purity Tests Explained: HPLC, Mass Spectrometry and COAs
A 99% purity claim can be real and still leave important questions unanswered.
Survodutide Phase 3: What SYNCHRONIZE-1 Actually Found
Phase 3 is positive, but the headline 16.6% needs context.
GHK-Cu vs Matrixyl vs Argireline: Popular Skin Peptides Compared
Three famous cosmetic peptides, three different mechanisms, and a much smaller evidence base than the marketing suggests.
SS-31 vs MOTS-c: How the Mitochondrial Peptides Differ
Two mitochondrial peptides, two very different evidence records.
Thymosin Alpha-1: What Do the Human Trials Actually Show?
Decades of human research, promising early signals, and two large trials that changed the picture.
AOD-9604 peptide explained: what is it and what has research found?
A fat loss peptide that reached large human trials, then failed the test that mattered most.
What Are Peptides? Types, How They Work and What the Science Actually Says
A plain English guide to what peptides are, what they do and why the evidence matters.
Retatrutide Explained: How the Triple Agonist Works and What the Latest Research Shows
What retatrutide is, why it is getting attention and what current trials actually show.
BPC-157: What Does the Human Evidence Actually Show?
A clear look at the gap between BPC-157 hype, animal research and the very limited human data.
Semaglutide vs Tirzepatide vs Retatrutide: What's the Difference?
A straightforward comparison of how these three metabolic drugs work and what separates them.
GHK-Cu / Copper Peptides: What Do They Actually Do for Skin and Hair?
A plain English look at what copper peptides are, how GHK-Cu is used and what the evidence says for skin and hair.
Peptides for Weight Loss: What Does the Evidence Actually Support?
Which weight loss peptides have real human evidence and which claims run ahead of the science.
TB-500 Explained: Thymosin Beta-4, TB-500 and the Evidence People Often Confuse
An evidence led guide to what TB-500 is, how it relates to thymosin beta-4 and where confusion often starts.
BPC-157 vs TB-500: What's the Difference and What Does the Evidence Show?
A clear side by side look at how these two recovery peptides differ and what the evidence actually supports.
Peptides for Injury Recovery: What Do We Actually Know About BPC-157 and TB-500?
What current research says about injury recovery peptides, tissue repair and the evidence behind the claims.
CJC-1295 + Ipamorelin: What Is the Combination and Has It Actually Been Studied?
A straightforward guide to why CJC-1295 and ipamorelin are paired and what the human research actually shows.
The Wolverine Stack: What Are BPC-157 and TB-500, and Does the Combination Work?
Why BPC-157 and TB-500 are sold together, and the trial that would settle it has not been done.
GHK-Cu for Hair Growth: What Does the Research Really Show?
The hair study everyone cites tested a different copper peptide, and the newest human report used three drugs at once.
Cagrilintide and CagriSema Explained: How Do They Compare With Semaglutide and Tirzepatide?
An amylin drug added to semaglutide beats semaglutide alone, but it did not keep pace with tirzepatide head to head.
CJC-1295 vs Ipamorelin vs Sermorelin vs Tesamorelin: What's the Difference?
Four growth hormone peptides that sound alike, with very different evidence behind them.
Melanotan II (MT2): What Is It, How Does It Work and What Are the Risks?
The tanning peptide that clearly works on skin, and why that is only half the story.
The GLOW and KLOW Peptide Stacks: What's Actually in Them and Is There Any Evidence?
Four interesting molecules in one vial do not add up to four evidence bases, and nobody has tested the mix.
KPV Peptide: Why Is Interest Growing and What Does the Research Actually Show?
A tiny fragment of a natural hormone with good mouse colitis data and no human studies at all.
MOTS-c: What Is the Mitochondrial Peptide and What Does the Human Evidence Show?
A peptide made by mitochondria with striking mouse results, and no completed human treatment trial.
Semax: What Is the Peptide, How Does It Work and What Evidence Exists in Humans?
Real Russian stroke research, a large animal literature, and much less behind the nootropic claims.
PT-141 (Bremelanotide): How Does It Work and What Does the Clinical Evidence Show?
The rare online peptide that became a real medicine, and why its approval is much narrower than the marketing.
How Peptides Are Actually Made
How amino acids become peptides, why purification matters and what a purity percentage really tells you.
Nothing here yet
No published post matches. Every compound already has an evidence record in the peptide directory, and the studies index is searchable too.
Evidence records matching your search
Browse by topic
Nine ways in
5 posts
Start here
What peptides are, how they work, how they are made and how to read the evidence.
8 posts
Metabolic & incretin
Semaglutide, tirzepatide, retatrutide, cagrilintide and the receptors behind them.
9 posts
Tissue repair
BPC-157, TB-500, KPV and the gap between animal healing data and human trials.
5 posts
Growth hormone axis
CJC-1295, ipamorelin, sermorelin, tesamorelin and how the axis is actually regulated.
7 posts
Dermatological
GHK-Cu, Matrixyl, Argireline, melanocortins and what skin trials really measure.
3 posts
Longevity & mitochondrial
MOTS-c, SS-31, Epitalon and the claims made for ageing biology.
4 posts
Neuroactive
Semax, DSIP and the neuropeptides discussed for cognition and sleep.
3 posts
Quality & analysis
Synthesis, HPLC, mass spectrometry, purity and what a certificate of analysis leaves out.
5 posts
Evidence & regulation
Reading trials, weighing evidence and following regulatory decisions.
Looking for a specific molecule rather than a question? The peptide directory holds the structured evidence record for all 196 compounds.