“Peptide” describes what a molecule is made of, not what it does. GLP-1 drugs are peptides, and so are BPC-157 and GHK-Cu, even though they do completely different things.
What Makes Something a Peptide?
Amino acids are the building blocks of protein. String a few of them together and you have a peptide. String a lot together and you have a protein. There’s no hard scientific line between the two, but the FDA uses one for regulation: a chain of more than 40 amino acids is a protein.
By that rule, semaglutide and tirzepatide are peptides, and HGH, at 191 amino acids, is a protein.
Is GLP-1 a Peptide?
Yes. GLP-1 (glucagon-like peptide-1) is a hormone of about 30 amino acids that cells in your gut make after you eat. It tells your pancreas to release insulin, slows your stomach and turns down appetite.
Your own GLP-1 doesn’t last. An enzyme called DPP-4 breaks it down within a minute or two. GLP-1 drugs are peptides changed so they survive: semaglutide has one amino acid swapped to resist DPP-4, and a fatty acid that makes it stick to albumin, a protein in your blood. That’s why one shot lasts a week. The semaglutide half-life calculator shows how the level rises and falls between shots.
Is Semaglutide a Peptide?
Yes. Semaglutide is the peptide in Ozempic, Wegovy and the Rybelsus tablet. The Ozempic label calls it a GLP-1 analog with a “peptide backbone”, 94% the same as human GLP-1. The pill is the same peptide in tablet form.
Is Tirzepatide a Peptide?
Yes. Tirzepatide, the drug in Mounjaro and Zepbound, is a peptide of 39 amino acids based on the sequence of another gut hormone, GIP. It acts on both the GIP and GLP-1 receptors, which is the difference between it and semaglutide. Like semaglutide, it carries a fatty acid that lets it last a week.
Retatrutide goes one step further: a single peptide that acts on GIP, GLP-1 and glucagon receptors. How the three compare on weight loss and side effects is in semaglutide vs tirzepatide vs retatrutide.
Are Peptides Like Ozempic?
Only the GLP-1 ones. Semaglutide, tirzepatide and retatrutide all work on the GLP-1 receptor. Most of the peptides people buy for recovery, skin or energy don’t. BPC-157 is a 15-amino-acid fragment of a stomach protein. GHK-Cu is three amino acids bound to copper, and MOTS-c is a 16-amino-acid peptide made in your mitochondria. None of them is a GLP-1, and none has trial data for weight loss.
Plenty of people run both. Among Regimen users on a GLP-1, the peptides they add most are MOTS-c (18%), GHK-Cu (17%) and KLOW (14%). The GLP-1s with the strongest fat-loss evidence, and the peptides people pair with them, are in the best peptides for fat loss.
Is It a Peptide? A Quick List
Peptides
- Semaglutide (Ozempic, Wegovy, Rybelsus)
- Tirzepatide (Mounjaro, Zepbound)
- Retatrutide
- BPC-157, TB-500, GHK-Cu, MOTS-c, KPV
- CJC-1295, ipamorelin, sermorelin
Longer chains the FDA counts as proteins
- Insulin (51 amino acids)
- Tesamorelin (44 amino acids)
- HGH, or somatropin (191 amino acids)
Not peptides at all
- NAD+: a coenzyme made of two nucleotides
- MK-677 (ibutamoren): a small, non-peptide molecule taken by mouth
- Testosterone and other steroids: built on a four-ring carbon core
What each one is used for: the list of peptides.
Is NAD a Peptide?
No. NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell, made of two nucleotides joined together. There isn’t an amino acid in it. It gets called a peptide because it’s sold by the same sellers, mixed with the same bacteriostatic water and injected the same way. Among Regimen users on a GLP-1, 17% take NAD+.
Is HGH a Peptide?
It’s usually called a peptide hormone, but at 191 amino acids it’s a protein by the FDA’s definition. It’s not a steroid either. Where HGH sits next to testosterone, and how each is regulated, is in peptides vs steroids.
Is MK-677 a Peptide?
No. MK-677 (ibutamoren) acts like a growth hormone peptide, because it switches on the ghrelin receptor and raises growth hormone, but it’s a small non-peptide molecule. That’s why it works as a pill. It’s banned in tested sport, alongside the growth hormone peptides.
Does Being a Peptide Mean It’s Safe?
No. Calling something a peptide says nothing about whether it’s been tested. Semaglutide and tirzepatide are approved drugs with large trials and labels. Retatrutide is investigational. BPC-157, MOTS-c and most peptides sold online are not approved for human use and have little human data. Are peptides safe? covers what’s known about each group.
Track Your GLP-1 and Peptides in One App
Regimen is a GLP-1 tracker and a peptide tracker in one: a free medication-level chart for your GLP-1, half-life tracking for each peptide, and food noise, nausea and energy next to every dose.
Sources
- Semaglutide: Ozempic prescribing information, sections 11 and 12.1; Rybelsus and Ozempic tablets; Wegovy.
- Tirzepatide: Zepbound prescribing information, section 11; 39 amino acids: Peptides, 2024.
- Retatrutide: Coskun et al., Cell Metabolism, 2022; status: Lilly, July 23, 2026.
- GLP-1: Holst, Physiological Reviews, 2007; half-life: Müller et al., Molecular Metabolism, 2019.
- Peptide vs protein: 21 CFR 600.3(h)(6).
- Insulin: NLM MeSH. HGH: Genotropin prescribing information. Tesamorelin: Egrifta WR prescribing information.
- BPC-157: NLM MeSH. GHK: PubChem. MOTS-c: Lee et al., Cell Metabolism, 2015.
- NAD+: NLM MeSH. MK-677: Holst et al., Molecular Endocrinology, 2005; Nass et al., Annals of Internal Medicine, 2008.
- Sport: WADA 2026 Prohibited List.
- Regimen app data: compounds people logged as taken in the 30 days to October 26, 2026.
All sources checked October 26, 2026. This article is for education and tracking. It is not medical advice.
Frequently asked questions
Is Wegovy a peptide?
Yes. Wegovy is semaglutide, the same peptide as Ozempic, approved for weight loss and sold as a weekly pen and a daily tablet. The tablet carries the same peptide plus an ingredient that helps it get absorbed through the stomach.
Is retatrutide a peptide?
Yes. Retatrutide is a single peptide that acts on three receptors, GIP, GLP-1 and glucagon. It isn't approved yet: Lilly has reported large trials and plans to file for US approval in early 2027.
Are proteins peptides?
Proteins are long peptides. Both are chains of amino acids; the difference is length. The FDA calls any chain of more than 40 amino acids a protein, which is why HGH, at 191 amino acids, is a protein and semaglutide is a peptide.
Are peptides natural?
Your body makes thousands of them, GLP-1 among them. The ones sold as drugs or research compounds are made in a lab, often changed from the natural version so they last longer. Semaglutide, for example, has a fatty acid attached so it lasts a week instead of minutes.
What app tracks a GLP-1 and peptides together?
Regimen tracks GLP-1s and peptides in one app: dose logging with custom scheduling and dose titration, a free medication-level chart, half-life tracking for peptides, injection site rotation, side effects and 50+ daily markers, weight and bloodwork. Free for one compound, no time limit; Premium if you track more than one.
