Thought experiment, and I'm curious where this lands.

Say a lab gets funding to run one properly designed human trial on one research peptide. One compound, one year, real controls, real endpoints, published either way. They can only pick one.

Which one is the best use of that money?

I don't mean which one you find most exciting. I mean which one would change the most if somebody finally ran the trial. Which gap is costing us the most.

My pick: BPC-157

Not because I think it's the strongest compound. Because it's the biggest gap between how much it gets used and how little human data exists.

A 2025 systematic review screened 544 articles on it, and the human clinical trials are still basically absent. It just went through an FDA advisory panel where the agency's own scientists said there wasn't enough human safety data, and the panel recommended it anyway, 8 to 6.

So we've got a compound that's everywhere, with a huge animal literature, no real human trials, and a regulatory decision pending. One good trial would settle more arguments than anything else on the list.

Two other candidates I considered

LL-37. It has human randomized trials, all topical. Injectable use has no published human pharmacokinetics. One well-designed injectable study would close a gap that thousands of people are currently guessing at.

Epitalon. All the human outcome data belongs to Epithalamin, the extract. The synthetic has never had a human trial of its own. That's a clean, answerable question.

Your pick

Name one compound and say what the trial would settle. That second part is the interesting one.

And if you think the money is better spent proving one of these doesn't work, say that too. Negative results are worth as much and get funded a lot less.

For research use only. Not for human or veterinary consumption. This post is educational and is not medical advice.

Full doses and bloodwork are in the pinned cheat sheet.

Join the Discord.

Sermorelin gets treated like the weak option in the GH peptide conversation. Fair on potency. Completely misses what makes it interesting this year.

What it is

Sermorelin is GRF(1-29). Your natural GHRH is 44 amino acids long, and sermorelin is the first 29 of it. That's the shortest piece that still fully activates the pituitary GHRH receptor and triggers a GH release.

So it's not an analog trying to imitate GHRH. It's the working end of the real thing.

The regulatory history is the story

	Sermorelin	CJC-1295 no DAC	Ipamorelin
Ever FDA approved	Yes, 1997, as Geref	No	No
Why it left the market	Business, 2008. Not safety	Never on it	Never on it
Compounding footing	Strongest in the class	Flirted with Category 2 in 2024	Flirted with Category 2 in 2024

That's the part people skip. Sermorelin was approved by FDA in 1997 for pediatric GH deficiency. EMD Serono pulled it in 2008 because a niche peptide couldn't compete economically with entrenched growth hormone products. It was not withdrawn for safety.

Prior approval, non-safety withdrawal, established safety profile. In a year where the whole conversation is about what compounding pharmacies can legally use, that history gives sermorelin the cleanest position of any GH secretagogue.

Now the honest part about the data

The adult evidence is thin. The clinical case basically rests on one study from 1997: 19 elderly subjects, 16 weeks, single blind. Lean mass went up about 1.26 kg in the men, not in the women. No fat loss. No change in bone density.

Compare that to tesamorelin, which has an 816 patient Phase III program behind it. That gap is not subtle, and anybody telling you sermorelin is as proven as tesamorelin is wrong.

Where it earns its spot

Clean selectivity. No cortisol, no ACTH, no prolactin elevation.

It also leaves the somatostatin feedback brake intact, so the stimulus stays pulsatile instead of sustained. That's a gentler signal, and it tends to be better tolerated by people who run into edema on tesamorelin.

The simple split: if visceral fat is the research target, tesamorelin has the data. If the question is recovery support, or legal clarity matters, sermorelin is the one with the paperwork.

Two questions.

Does prior FDA approval change how you weigh a compound, or is only the trial data worth anything to you?

And is a gentler pulsatile signal a feature or just a weaker one?

For research use only. Not for human or veterinary consumption. This post is educational and is not medical advice.

Full doses and bloodwork are in the pinned cheat sheet.

Join the Discord.

VIP stands for Vasoactive Intestinal Peptide, which is one of the worst names in this whole space. It's named after the first thing anybody noticed it doing, back when that's how naming worked. Neither word describes what it's mostly studied for now.

What it does instead

VIP is a 28 amino acid neuropeptide, and its main job is immune tolerance. Meaning it doesn't just turn inflammation down, it teaches the immune system what to leave alone.

It programs dendritic cells to make regulatory T cells. It shifts macrophages from the inflammatory state into the repair state. It keeps the gut barrier intact. And it helps keep the master circadian clock in the brain synchronized.

None of that is vasodilation.

The receptor part is where it gets good

VIP works through two receptors, and which one it hits depends on what the immune system is already doing.

Receptor	Where it shows up	What it does
VPAC1	Resting cells	Dampens inflammation that's happening right now
VPAC2	Goes up on activated T cells	Programs long term tolerance

Fire extinguisher and architect. Same molecule, two completely different jobs depending on the state of the cell it lands on. I don't know another peptide on the list that does that this cleanly.

The half-life explains the trial split

VIP has a plasma half-life of about one minute. One.

Now look at what happened in the trials.

TESICO, Phase 3, 471 people. IV aviptadil, which is synthetic VIP, in COVID ARDS. Stopped for futility.

Inhaled aviptadil, Phase 2 randomized trial, 80 people. Hospital stay 7.8 days against 10, better oxygenation, better imaging.

Same molecule. Different route. Opposite results.

With a one minute half-life, IV can't hold exposure in lung tissue long enough to matter. Inhaled puts it directly on the target. So the Phase 3 failure reads more like a delivery problem than a drug problem. Not proof, but it's the most sensible explanation on the table.

Where the evidence is decent and where it isn't

Controlled human evidence exists for pulmonary immune work: the sarcoidosis Phase II with TNF-alpha down and regulatory T cells up, hemodynamic improvement in pulmonary hypertension, and the inhaled COVID trial.

The mold illness and CIRS use, which is what most people have heard about, rests on one practitioner's cohort. Large, over 10,000 people, but no independent replication and no randomized trial. Both of those things are true at once and any real assessment has to say both.

Two questions.

Does the route explanation hold up for you, or do you read the Phase 3 failure as the drug failing?

And what other peptide do you think is stuck with a name that misleads people about what it does?

For research use only. Not for human or veterinary consumption. This post is educational and is not medical advice.

Full doses and bloodwork are in the pinned cheat sheet.

Join the Discord.

GLOW and KLOW are two of the most asked-about products in here, and most of the questions are some version of "which one." So let me break down what's in each one, what the fourth peptide in KLOW is doing, and the part about both blends that almost nobody looks at.

What's in them

	GLOW	KLOW
GHK-Cu	Yes	Yes
BPC-157	Yes	Yes
TB-500	Yes	Yes
KPV	No	Yes
Typical course	Shorter, around 4 weeks then a rest period	Longer, 8 to 12 weeks

Same three peptides in both. KLOW adds KPV.

What each one is doing

GHK-Cu. Copper peptide. It doesn't just build collagen, it tells tissue how to organize the collagen it's already making. Also antioxidant and anti-inflammatory.

BPC-157. Restores blood flow to tissue that isn't getting it, and calms inflammation without shutting it down.

TB-500. Cell migration and new blood vessel formation. It's the one that helps repair land as organized tissue instead of scar.

KPV. This is the KLOW difference. It's a tripeptide that works on NF-kB signaling, which is one of the main switches for inflammation. Where BPC-157 modulates inflammation as part of a repair program, KPV goes at the inflammatory signaling directly.

The simple way to think about it: GLOW is a repair blend. KLOW is a repair blend with a dedicated anti-inflammatory added.

The part nobody checks

Look at the ratios, not the ingredient list.

In GLOW, GHK-Cu is roughly 70% of the vial by weight. In KLOW it's a little over 60%. The three peptides everybody buys these blends for, BPC-157, TB-500, and KPV, split the rest.

So both of these are mostly a copper peptide product with repair peptides riding along. That's not a knock, GHK-Cu is the one with the longest research history of the group. But if somebody is buying KLOW mainly for the KPV, KPV is about an eighth of the vial.

And the ratio is fixed. You can't turn up the TB-500 side without turning up everything else, which matters because TB-500 in the standalone research is a bolus compound a couple times a week, not a small daily amount. Same problem I went through with the BPC and TB-500 blend.

So which one

Depends on what the research question is.

If inflammation is the thing being studied, KLOW has the extra tool. If it's straight tissue repair, GLOW has the same three actives and a shorter protocol. If the question is specifically about one of the four peptides, neither blend is the right instrument, because you can't move one lever by itself.

Doses and reconstitution for both are in the pinned cheat sheet.

Two questions.

Anybody compared GLOW against KLOW on the same kind of research target? I'd want to know if the KPV made a difference you could see.

And did you know GHK-Cu was that much of the vial before reading this?

For research use only. Not for human or veterinary consumption. This post is educational and is not medical advice.

Full doses and bloodwork are in the pinned cheat sheet.

Join the Discord.

What do you like best? Was thinking the Magic Trackpad but for some reason highlighting while having to scroll was not a good experience for me on the macbook. so for the mini not sure if i should get that or a mouse.

Weight loss is the most asked-about topic here, and the confusion is always the same: people compare these like they all do the same job. They don't. Here's the full roster in plain language, what each one actually does to your body, and who should reach for it. Find yourself in the list.

Semaglutide (Ozempic, Wegovy) 
What it does: mostly works on appetite and fullness, plus it slows down how fast your stomach empties, so the main effect you feel is eating less without white-knuckling cravings all day. It's not a metabolism booster, it's a hunger reducer. Around 15% of body weight lost in trials. Weekly injection. Main side effects are nausea and constipation, worst when you raise the dose. You'll notice appetite drop in 1 to 2 weeks, real weight loss over 3 to 4 months. (It's a GLP-1, the original of this class.) Who should lean toward it: you've got weight to lose and you want the option with the longest safety record and the most people who've used it, even if it's not the strongest. A solid, cautious first choice.

Tirzepatide (Mounjaro, Zepbound) 
What it does: same appetite-killing effect as semaglutide, but it hits a second hunger pathway on top of the first, so it works noticeably stronger. People lose more on it, around 21 to 22% in trials, and when the two were tested directly against each other, it won (20.2% vs 13.7%). Weekly injection, same nausea/GI side effects, tolerated about the same. (Adds a receptor called GIP, which is why it's a "dual" agonist.) Who should lean toward it: you want the most weight loss you can actually get prescribed right now, or you tried semaglutide and it wasn't enough or stopped working. For most people serious about real weight loss with approval behind it, this is the current best pick.

Retatrutide 
What it does: same appetite suppression as the other two, but it adds a third effect, it nudges your body to burn more energy, not just eat less. So you're getting hunger reduction plus a metabolic boost at the same time, which is why it's posting the biggest numbers anyone's seen, around 24% in earlier trials and about 28% in the latest one. The catch: it's still in clinical trials and not approved, so the only way to access it is through a trial, not a prescription or a compounding pharmacy, and there's less long-term safety data. Weekly injection, and it has the most intense nausea/GI of the three. (It's a "triple" agonist, adding a hormone pathway called glucagon.) Who should lean toward it: you're chasing the absolute highest weight loss possible and you've likely already maxed out tirzepatide, and you accept that it's unapproved and less proven. Not your move if you want the safe, established route.

Liraglutide (Saxenda, Victoza) 
What it does: the older version of semaglutide. Same appetite-reducing idea, but you have to inject it every day instead of once a week, and it works less well, roughly 5 to 8% in real-world use. You build up to the full dose over about 5 weeks. Who should lean toward it: realistically only if you already have it, tolerate it well, or can't get the newer weekly options. For most people it's been replaced. Worth knowing it exists, rarely the first choice now.

Tesamorelin 
What it does: this one does NOT touch your appetite. It works completely differently, it raises your body's growth hormone, and its specific job is shrinking visceral fat, the deep belly fat packed around your organs (different from the soft fat you can pinch). It's not for dropping overall scale weight, it's for that hard, deep gut. Around 15 to 20% reduction in that deep fat over about 6 months. Daily injection, taken on an empty stomach. Side effects are mostly injection-site irritation and some water retention. Slow to show, this is a months-long play. One important note: it's FDA-approved specifically for visceral fat in people with HIV-related fat changes. For general "I want my deep belly fat gone" use, it's off-label / research-context, not a broadly approved belly-fat drug. Who should lean toward it: your weight is roughly where you want it but you've got a stubborn hard belly that won't go, or you've already lost weight on a GLP-1 and the midsection is the last holdout. You're targeting deep belly fat specifically, and it's often run alongside a GLP-1, not instead of one.

CJC-1295 and Ipamorelin 
What they do: also not appetite drugs. They bump up your own growth hormone in natural pulses, which helps you hold onto muscle, recover better, and slowly improve body composition. They're not real fat-loss drivers, there are no weight-loss trials behind them, and the muscle-saving benefit is more theory-from-how-GH-works than directly proven. Daily, usually before bed. Mild side effects. Who should lean toward them: you're already losing weight (usually on a GLP-1) and you're worried about losing muscle along with the fat. This is a muscle-protection and recovery add-on during a cut, not something that drives weight loss on its own.

AOD-9604 
What it does: it's a piece of the growth hormone molecule, meant to trigger fat burning directly without the other growth-hormone effects. That's the theory. In practice the human evidence is weak, one study showed about 2.6 kg lost vs 0.8 kg on placebo over 12 weeks, others showed basically nothing, and a review concluded it doesn't meaningfully work in humans. Small results at best. Daily, over 6 to 8 weeks. Who should lean toward it: honestly, almost nobody as a main tool. If you specifically want a non-appetite, direct fat-burning approach and you understand the evidence is thin and the results small, it's a minor add-on at most. Not for anyone who wants reliable, real weight loss.

5-Amino-1MQ 
What it does: a pill, not an injection. It blocks an enzyme that's overactive in fat cells, which in theory frees those cells to burn more fat and raises your cellular energy (NAD+), all without touching your appetite. In mice it caused fat loss without them eating less. The problem: there are no human weight-loss studies at all yet. Usually taken as 50 to 100 mg twice a day. Who should lean toward it: you want an oral, no-needles option with an energy/metabolism angle and no appetite effect, and you fully accept it's almost completely unproven in people. An experiment, not a dependable tool.

MOTS-c 
What it does: a peptide that acts like an "exercise signal," it switches on a pathway (AMPK) that improves how your body handles energy and stamina. In mice it improved insulin sensitivity and reduced obesity, but in humans the research is very early and about metabolic health and endurance, not weight loss. No real human weight-loss data. Who should lean toward it: someone interested in metabolic health and endurance support, not someone trying to lose weight. Don't pick this for the scale.

PYY 
What it does: a natural "I'm full" hormone your gut already makes. On its own it doesn't work well as a weight-loss drug because it doesn't last long in the body. But a 2024 study found that adding it to semaglutide beat semaglutide alone, so its real future is probably as a sidekick to a GLP-1, not a standalone. Who should lean toward it: nobody yet as a solo option. Worth watching as a future add-on to a GLP-1, not something to run by itself.

If you're stuck between two 
These are the matchups people actually get hung up on.

Semaglutide vs tirzepatide: want the stronger result and can get it? Tirzepatide, it won head-to-head. Go semaglutide only if cost, access, or a longer comfort history matters more to you than maximum loss.

Retatrutide vs tirzepatide: tirzepatide if you want approved, available, and proven. Retatrutide only if you've truly plateaued on tirzepatide and you're willing to run something still in trials for the extra few percent. For most people, tirzepatide is the answer and reta is the "maybe later" option.

GLP-1 vs tesamorelin: the one people get most wrong, because it's not either/or. Got weight to lose? A GLP-1. Weight's fine but the deep belly won't budge? Tesamorelin. Both problems? That's the case for running them together, not choosing between them.

GLP-1 alone vs GLP-1 plus a GH peptide: only add CJC/Ipamorelin or tesamorelin if muscle loss or a stubborn midsection is your specific concern. If you just want the weight down, the GLP-1 alone does the heavy lifting.

Which one are you leaning toward, and what's the goal you're actually chasing? Stuck between two? Drop them below and people can weigh in.

Seeing a lot of the same beginner questions lately so figured I’d repost this for newer people in here.

bodyhackguide.co

Has a bunch of peptide breakdowns, calculators, dosing/reconstitution stuff, and general recovery info all in one spot.