A physician’s primer on the most-discussed compounds in longevity medicine.
If you’ve spent any time on longevity podcasts, biohacking forums, or the social media feeds of fit people in their forties and fifties, you’ve heard about peptides. The pitch is usually some combination of “fountain of youth,” “off-label miracle,” and “what the pros are using.” That framing is exciting. It’s also, in our experience, mostly wrong.
This article is what we wish more patients heard before their first call — the boring, accurate version. It is general education, not medical advice, and it does not describe how we dose or sequence anything for our own patients.
A peptide is a short chain of amino acids — the same building blocks that make up every protein in your body. Proteins are typically large (insulin is technically a peptide hormone, but most proteins have hundreds of amino acids). Peptides are smaller, usually fewer than fifty residues. Your body already produces thousands of them. They act as signals: telling cells to grow, repair, sleep, release hormones, calm inflammation, or behave a certain way.
Therapeutic peptides — the kind we prescribe — are synthetic versions of those naturally occurring signals, or close analogs designed to bind the same receptors. Insulin, GLP-1, oxytocin, parathyroid hormone, and dozens of FDA-approved drugs are peptides. So this is not a fringe idea. It is mainstream pharmacology with a sexier marketing wrapper in the longevity space.
These drugs restore and amplify the gut-to-brain-to-pancreas signal that tells your body it’s well-fed — with downstream benefits on heart, kidney, and brain that go far beyond appetite.
It helps to group the most-asked-about compounds by what they actually do, rather than by hype:
The GLP-receptor agonists — semaglutide, tirzepatide, retatrutide. These are FDA-approved for type 2 diabetes and obesity, and they are reshaping cardiometabolic medicine. The cardiovascular outcome data is real. The weight loss is real. The cancer-survival, kidney, and cognition signals are early but interesting. We cover this family in its own article.
BPC-157 and TB-500 (thymosin beta-4) are the two most-asked-about compounds in this category. Both have strong preclinical literature for tendon, ligament, and gut tissue repair. Human evidence is thinner, mostly small or anecdotal. They are not FDA-approved. They are also not, as the internet sometimes suggests, magic.
CJC-1295, ipamorelin, sermorelin, tesamorelin. These compounds nudge your pituitary to release a more youthful pulse of growth hormone. They are not the same as injected human growth hormone, and the side-effect profile is generally milder. The effects most patients notice — better sleep depth, recovery, body composition — track with that mechanism.
Thymosin alpha-1 (immune modulation), selank and semax (Russian-developed nootropic peptides), cerebrolysin (a peptide-mix studied in stroke recovery). The literature here ranges from solid (thymosin alpha-1 in chronic infection) to genuinely speculative.
Most therapeutic peptides outside the FDA-approved metabolic family are not stocked at your corner pharmacy. They are made to order by 503A state-licensed compounding pharmacies — the same kind of pharmacy that compounds bioidentical hormones, custom dermatologic creams, and pediatric dosage forms. A licensed physician writes the prescription; the compounding pharmacy prepares it under USP <797> sterile-compounding standards.
Compounded does not mean unregulated. It means individualized. The trade-off is that compounded products do not carry FDA approval for the specific indication, which is why responsible practices use them under physician supervision, with informed consent, lab monitoring, and conservative dosing.
You won’t find specific dose ranges, cycling windows, or stacking sequences here. That’s deliberate. Those decisions are clinical and individualized — and we reserve our actual protocols for our Transcend members, who are evaluated, monitored, and supported throughout treatment. Publishing dosing guides on the open internet is, in our view, irresponsible — both for patients (who deserve evaluation first) and for the field (which already has too much hype and not enough rigor).
Our members get the full library: peptide stacks, cycling windows, dose ranges, lab-monitoring schedules and what to do when results plateau. Reviewed and adjusted by Drs. Sylvia and Michael Harris.
Start with a Foundations telehealth visit ($79, no commitment). We’ll do a real history, review labs, and talk honestly about whether peptides make sense for your goals — or whether the foundations need work first. Sometimes the most useful thing a physician can tell you is “not yet.”