Peptides 101: What They Actually Are
Ask the Experts, Part 1 of 3 Peptides are everywhere in the wellness conversation right now: whispered about in group chats, sold in slick packaging on Instagram, credited with everything from glowing skin to weight loss to "biohacked" longevity. But for many people, the word "peptide" is still just a buzzword. So we thought of starting with the base and went straight to the source. We sent the same eight questions to three doctors who work with peptides every day, Dr Haytham Salem - Hortman Clinics, Dr Tatijana Pavicic -Private Practice, and Dr Jennifer Kaur- Craft Clinic, and asked them to cut through the noise. This is Part 1 of a three-part series. We're starting with the basics: what a peptide actually is, and why lumping them in with steroids and growth hormone is one of the biggest, and most persistent, myths out there.
So, what is a peptide?
Let’s strip away the marketing, and the definition is simple. As Dr Jennifer Kaur of Craft Clinic puts it:
"A peptide is a small chain of amino acids (the building blocks of proteins) that acts as a messenger in the body, telling cells what to do."
Dr Tatjana Pavicic describes it almost the same way, but adds an important nuance: the job a peptide does depends entirely on which peptide you're talking about:
"Peptides are short chains of amino acids, the same building blocks that make up proteins, and many of them act like messengers that tell your cells to do a specific job. Depending on the peptide, that job might be making collagen, healing a wound, or controlling appetite."
Dr Haytham Salem leans on an analogy that's stuck with us:
"I usually tell people that peptides are simply tiny proteins our bodies naturally use to communicate. Think of them as text messages between cells, telling the body when to repair, recover, grow, or regulate different functions."
Notice what all three have in common: none of them describe a single substance. A peptide isn't one thing, it's a category, the same way "vehicle" describes both a bicycle and a lorry. Which brings us to the myth that trips up nearly everyone.
Myth: "Peptides are basically the same as steroids or growth hormone."
This is, according to Dr Salem, one of the most common misconceptions he hears in clinic, and it's simply not true.
"Steroids replace or mimic hormones. Growth hormone is a hormone itself. Peptides are different. Most act more like messengers, gently encouraging the body to do what it already knows how to do rather than forcing it down a particular pathway."
Dr Pavicic agrees, and offers a way to picture it:
"Peptides are not steroids, and they are not growth hormone. Peptide is simply the word for a molecule built from amino acids... Think of the word peptide the way you think of the word vehicle. A bicycle and a lorry are both vehicles, yet they do entirely different things."
She points out that the confusion usually starts because some peptides do interact with the body's growth hormone pathways, but that's a small slice of a much bigger picture:
"The weight-loss injections many people now recognise, based on ingredients such as semaglutide, are also peptides, and they act on appetite and blood sugar, not on muscle."
Dr Kaur breaks it down further with a specific example, explaining that different peptides work through entirely different biological pathways:
"For example, ipamorelin acts on the ghrelin (GHS-R1a) receptor, gently signalling the body's own growth hormone pathway. That doesn't mean it's growth hormone itself, and it doesn't behave like anabolic steroids. Some target GLP-1 receptors to help regulate appetite and blood sugar, while others influence tissue repair or immune signalling."
One thing to remember
Peptides aren't a shortcut, a steroid substitute, or a single miracle molecule. They're a huge and varied family of messengers, each with its own job. Understanding that is the first step before anyone starts asking whether a particular peptide might be right for them.
In Part 2, we're tackling the myth that "natural" automatically means "safe," the real difference between topical and injectable peptides, and why more is almost never better when it comes to dosing.
This article is for educational purposes and reflects the views of the interviewed practitioners. It is not a substitute for individualised medical advice; always speak with a licensed doctor before starting any peptide therapy.