Exploring Peptides 🧬
Research-focused peptide education: what's been studied, in what (cells, animals, humans), and what we still don't know.
No hype. No protocols. Not medical advice.
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"I'm 42, my biological age is 77," Katherine Ryan said on the Jonathan Ross Show in April.
She has said she has lupus. These tests often disagree, even on the same person, and they aren't built for one headline number. (ITV; The Conversation)
China just approved its first GLP-1 weight-loss pill: Lilly's orforglipron.
It isn't a peptide. It's a small molecule, so no empty-stomach rule like oral semaglutide (Rybelsus/Wegovy pill).
ATTAIN-1, top dose: 12.4 kg lost at 72 weeks in those who stayed on it. (Lilly China)
On semaglutide (Ozempic/Wegovy), rare GLP-1 receptor gene variants were linked to 2.4% weight loss vs 8.8% in matched non-carriers.
On tirzepatide: 13.3% vs 15.2% (not significant).
13,725 adults, retrospective records, 6-12 months. Small groups (17 and 19). (Nature Metabolism)
Lifting may be the difference on tirzepatide.
Randomized: 120 adults on it 40 weeks. Both lost ~22 kg. Lifting group lost less lean soft tissue (3.57 vs 4.67 kg). Strength +10-18% vs 6-9% drop. (Nature Medicine)
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Stopping a GLP-1 was linked to about twice the rate of myocardial infarction, stroke, or death from any cause.
80,302 people with type 2 diabetes and no prior CVD, 301 Italian clinics. Observational.
People who stop may already be sicker. Not proof stopping causes it. (Lancet)
A peptide cheat sheet just passed 177K views and 3,900 bookmarks.
Those lists usually leave this out. For TB-500, MOTS-c and KPV, FDA has not identified any human exposure data. For BPC-157: no, or only limited, safety-related information.
Hype moves faster than trials. (FDA)
101K views on the retatrutide knee-arthritis headlines.
Two Phase 3 trials in NEJM. The ~63-70% vs 38% "pain cut in half" figure is a modeled week-68 responder analysis, not a raw share of everyone randomized.
Investigational. Not approved. (NEJM manuscript)
FDA (Nov 9): GLP-1 labels get a rare eye-risk warning.
NAION: sudden, painless vision drop in one eye; can be permanent. May notice on waking.
126 trials (134,253 people): 6.4/100k person-years vs 3.8 on placebo or other diabetes drugs. Potential risk, not proven cause. (FDA)
The "myostatin blocker" headline is half right.
Bimagrumab blocks activin type II receptors, which myostatin signals through. BELIEVE, week 48: 71% of weight lost on semaglutide alone was fat. Top combo: 92%.
Catch: DXA lean mass isn't muscle. Investigational. (Nature Medicine)
Science just dedicated a special issue to what GLP-1 drugs do beyond weight loss.
Fat remodeling. Addiction. Neurodegeneration. Cancer risk. Access.
Editorial take: not a panacea, rebound is real, and many brain and cancer claims are still open. (Science, Nov 5)
Retatrutide isn't approved yet and already has a challenger.
Celltrion's CT-G32 hits GLP-1, GIP, glucagon and amylin. In obese rats it beat retatrutide on weight at the same dose and lost less lean mass.
Rats only. Human trials planned for 2027. (SCOHIA / Celltrion)
Russian labs keep modifying GHK, the copper peptide in skin cream.
Change three amino acids at the end and, in rats, anxiety, pain or depression-like signals shift. Same scaffold, different behavior.
Animal data only. Not Copper Peptide itself. (Kursk / Kurchatov)
AstraZeneca is reportedly in talks to buy Rhythm, a company built on one peptide.
Setmelanotide works on the brain's MC4R hunger pathway, not GLP-1. It's studied for rare genetic obesity where hunger signaling itself is broken.
Neither company has confirmed. (WSJ, Reuters)
USP, which sets US drug quality standards, says the six peptides in HHS's draft policy have no USP monographs, no reference standards and no official names.
In plain words: there's no agreed test for what should be in the vial. USP says the policy lacks "essential safeguards."
Viral post, 124K views: retatrutide cut knee pain 70%.
NEJM paper: on a 10-point pain scale, the top arm improved 3.6 points. Placebo improved 1.9. Real drug effect: 1.8 points.
The 70% assumes everyone stayed on the drug. Investigational, not approved. Big result, not magic.
a16z's State of Longevity report: peptide enthusiasm "has outpaced the actual evidence," and unregulated suppliers raise questions about "what is actually in the vial."
For scale: the compounded peptide market is single-digit billions. Tirzepatide alone: nearly $44B in 9 months.
684K views on this claim: retatrutide had 9 heart events vs 1 on placebo.
True but misleading: 9 is three drug groups pooled (1,749 people) vs one placebo (586). 10 events total, in a trial not built for heart safety.
Proves neither safe nor risky. The outcomes trial will.
First human dosed: an AI-assisted 9-amino-acid peptide meant to get the immune system to clear senescent "zombie" cells, per Immorta Bio's Nov 2 release.
Given Oct 29 in Mexico, in a study of advanced cancer patients.
Results so far: none. Safety and efficacy: not established.
Viral: FDA "just cleared the first human trial" of age reversal.
That was Jan 28. ER-100, from Life Bio (co-founded by David Sinclair), is an eye gene therapy for glaucoma and NAION.
Interim: 3 patients, open-label, well tolerated through day 56. Visual fields better in 2 of 3.
An investor's post about getting 100 million umbilical cord stem cells, 70 million by IV, just passed 1M views.
The human data: a 2026 review found 3 small randomized frailty trials, about 208 people. Some mobility and grip gains. None measured lifespan.
Signal, not proof.