Peptides, Explained.

Good morning!

More likely than not, you’ve seen the word peptide thrown around. In gyms, on your social media, even around dermatologists. Rather than giving them a simple label and forgetting about them, this week we’re taking a look at what exactly peptides are, how they work, and what they do for you (or don’t). Let’s dig in!

Key Takeaways

• Peptides are short amino acid chains that bind to cell receptors and trigger specific responses like hormone release and tissue growth.

• Because peptides are fragile, and your stomach acid so strong, you can’t reap the benefits of peptides if you eat them.

• Most peptides lack standardized production oversight, long-term safety data, and can carry risks from disrupting tightly regulated biological systems

CORE

What are Peptides?

In essence, peptides are short chains of amino acids, typically between 2-50 of them linked together. You can think of amino acids as the building blocks for your body, at the most basic level. The sequence looks something like this: amino acids form peptides, and peptides form proteins. This distinction matters because size determines function.

Like creatine, peptides are naturally occurring. Your body already makes thousands of peptides, like insulin. So is GLP-1, the compound in Ozempic and Wegovy. Growth hormone is a peptide. Oxytocin, the hormone involved in bonding and childbirth, is a peptide. They literally are hormones, enzymes (though in most cases, these are actually proteins), and signaling molecules that tell your cells what to do.

The peptides being sold as supplements are synthetic versions of these naturally occurring molecules, designed to trigger specific responses in your body (like promoting collagen production, stimulate growth hormone release, speed tissue repair, suppress appetite, and so much more). The purpose of using peptides is to enhance processes your body already does, only better and faster.

Whether that actually happens is another question, because more isn’t always better.

How do Peptides Work?

Your cells have receptors on their surface; specific spots where molecules can attach and send signals inside the cell. Peptides work by binding to these receptors, like a key fitting into a lock. Each peptide has specific receptors it binds to most strongly, and each receptor triggers a specific response. Insulin primarily binds to insulin receptors, which tell cells to absorb glucose. Growth hormone primarily binds to growth hormone receptors, which tell cells to build tissue and burn fat. You get the idea.

Supplemental peptides work the same way. They're designed to mimic your body's natural peptides and bind to the same receptors, triggering the same responses, only amplified. The idea is that by flooding your system with these synthetic versions, you can enhance specific processes your body already does, like build more muscle, heal certain areas faster, suppress appetite more effectively, etc.

Take the GLP-1 peptide (Ozempic, Wegovy). Your intestines release GLP-1 after you eat to signal fullness and regulate blood sugar. Synthetic GLP-1 mimics this, telling your brain you're full even when you haven't eaten, which is why it works for weight loss.

As with many trends, it all seems like upsides. But whether injecting synthetic versions actually produces the claimed benefits safely is another question entirely.

Why Can’t You Just Eat Peptides?

You may be asking yourself, if peptides are just chains of amino acids, why can't you eat them like protein? This is a very valid question that deserves a proper answer. Because of the high acidity of your stomach acid, peptides break down easily when digested.

By the time they're absorbed, they're no longer the signaling molecule they were. Now they are just raw building blocks, no different from the amino acids you'd get from a chicken breast or eggs.

This is why peptide supplements are injected or applied topically. Injection bypasses digestion entirely, delivering the intact peptide directly into your bloodstream where it can bind to receptors. Topical application (for skin peptides) aims to get them absorbed through the skin barrier before they break down, though whether enough survives intact to be effective is debatable.

The Benefits of Peptides

Peptide supplements are generally marketed for three main categories:

• Cosmetics: The cosmetics industry has long been implementing peptides into everything from facial creams to shampoos. The ultimate goal is to make sure that the elastin and collagen in our skin stays as hydrated and healthy as possible, which can reduce the formation of wrinkles, strengthen hair, etc.

• Recovery: There are peptides that reportedly help to increase muscle growth and assist in post workout tissue and tendon repair.

• Overall Health: Supposedly they can also improve sleep quality, improve immune function and preserve lean muscle while dieting.

This all sounds very promising. But consider that there's a profound lack of large-scale human studies verifying most of these benefits or studying negative side effects, and the basis to take these falls apart.

The Real Risks

Beyond the lack of evidence, there are actual safety concerns. 

Unregulated production: Most peptides aren't FDA-approved, which means they're produced by compounding pharmacies without standardized oversight.

Unknown long-term effects: Most peptides marketed for performance or recovery have zero data on what happens with extended use in humans. Short-term studies in small groups don't reveal effects that emerge over years or decades.

Disruption of tightly regulated systems: Your body's signaling pathways operate in precise amounts at specific times based on immediate needs. Introducing synthetic peptides overrides this regulation.

Individual variability: People respond differently to the same peptide based on their existing hormone levels, receptor sensitivity, metabolism, and health status. What's safe for one person might trigger problems in another, and without clinical trials across diverse populations, these risks remain unidentified.

It is worth noting that FDA-approved peptides exist, like insulin, GLP-1 medications (Ozempic, Wegovy), growth hormone for specific medical conditions, and others have gone through rigorous approval processes. But most peptides you’ll see don’t fit into this category.

ENDNOTE

Final Thoughts

As the naturalist I am, I will always defend the basics first. Your body already produces the peptides it needs when given proper conditions: adequate sleep, whole food nutrition, regular movement, stress management. Chronic stress impairs collagen production. Poor sleep disrupts growth hormone release. Insufficient protein intake limits tissue repair.

However, that’s not to say they should never be used. Some conditions genuinely require peptide intervention. But for general optimization, consult a healthcare professional who can assess whether there's an actual deficiency warranting intervention, rather than self-prescribing compounds with limited human safety data.

Until next week!

Adrian Macdonald | Team Dietitian | The 8% Newsletter Author