Health

Peptide shots are the hot, new fad for anti-aging and building muscle — but no one really knows what they are

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Peptide shots are the hot new thing for anti-aging and muscle-building. Getty Images
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If you're not doing peptides, you're doing it wrong. That's according to avid gym-goers and longevity biohackers.

Peptides have become the buzziest new performance-enhancing treatment for people trying to optimize their bodies. So much so that GQ is calling peptides "the hottest thing on the fringes of fitness and anti-aging."

"There's this new kind of wedge in between supplements and prescription drugs that are called peptides," Dr. Andrew Huberman, a neuroscientist from Stanford (with a cult following of longevity-seekers), said recently on the Flagrant podcast. "I'll tell you right now, a lot of the bodies you see in Hollywood films are on peptides."

But the word peptide is actually quite vague and meaningless, when it comes to describing a health intervention. The truth is: we all have peptides inside our bodies right now — they're just chains of molecules (specifically, amino acids) that we produce naturally.

Here's what you should know:

Reasons people use peptides

Peptides are big in anti-aging circles. Insider recently reported on an 86-year-old who says she's "physically immortal" — she is doing peptides. So is billionaire longevity investor Christain Angermayer. Many biohackers claim peptides can improve brain power and joint health.

In the fitness world, some athletes swear by certain peptides for faster recovery from workouts and better stamina.

Those specializing in men's health are using peptides to "restore" or "balance" hormones, specifically testosterone, or to boost libido.

And the bodybuilding community has embraced peptides as a tool to boost muscle growth and burn fat faster, often used with various supplements in combinations known as "stacks."

How do you do peptides?

Most likely, when people say they're "doing peptides," they mean they are popping a pill or injecting a drug in the hopes of improving aging or building muscle.

You get peptides in weight loss (Ozempic contains a peptide that regulates blood sugar) and skincare (palmitoyl pentapeptide is used as an anti-wrinkling agent).

But when people talk about peptides for anti-aging and performance, they're usually talking about growth-hormone mimicking peptides.

"Certain peptides, for example, will make your body naturally produce more human growth hormones again," Angermayer, the longevity investor, told Insider. "Indeed, biohackers are very excited about it because you can practically make your body do certain things."

High demand has sparked a black market for peptides

Sermorelin is a particularly popular peptide. It prompts the body to release more growth hormone, which can help for building muscle mass or improving libido.

However, while sermorelin is available as a prescription drug, the high demand has led to shortages — which has sparked a whole shadow industry of unregulated sermorelin peddlers on the internet.

Many peptides are classified as biologics, which means there are strict laws around who can make and sell them.

In some cases, users are even sourcing peptides online from sites that market "research chemicals." While the vials are explicitly labeled not for human use, the sites are full of coded language hinting at "fast-acting, premium research gains" or products promising a "monster pump" or superior mass.

Risks of taking peptides incorrectly

While peptides are generally perceived as low risk since many are based on substances that naturally occur in the human body, the dose matters, and so do any potential additives or contaminants.

Some common peptides sold as fitness supplements, like creatine, have extensive research supporting the benefits and general safety in human use. However, other popular peptides are in early stages of study, often on mice instead of people.

As with all supplements, a lack of comprehensive regulation can make it difficult to know what you're getting, and how much. It's important to take the peptide hype with a grain (or even a whole shaker) of salt until the evidence catches up with what biohackers and influencers have claimed.

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Hilary Brueck
Hilary Brueck is a Health Correspondent at Business Insider, where she covers longevity and the quest to improve human aging. She also writes regularly about the complexities of diagnosing and treating cancer, the evolving landscape of GLP-1 drugs, new developments in exercise science, and expert-backed nutrition adviceIn general, she relishes any opportunity to unpack scientific discoveries or examine the latest consumer trends. Her reports have ranged from exploring how sherpas effortlessly climb into the thin air 29,029 feet above sea level to summit Mount Everest, to trudging along a Jersey shore beach with scientists fighting killer pandemic flu viruses by studying bird butts.She spoke with Dr. Anthony Fauci about his vitamin and supplement routine over a cold slice of pizza, and chatted with the world's oldest Nobel Prize winner in his basement solar lab. She also went an entire month without eating any ultra-processed foods (yes, it was time-consuming and challenging). A graduate of Columbia Journalism School and former Peace Corps Volunteer, Hilary speaks English, French, and Malagasy. Previously, Hilary reported for ABC News Radio, Fortune, Forbes, and Al Jazeera America. In her spare time, she likes to run, hike and she is also an aspiring (but very bad) surfer. If you've got a pressing health question, tip, or concern, reach out to hbrueck@bjinnox.com
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Gabby Landsverk
Gabby is a Health Correspondent with a focus on nutrition, fitness, longevity, and all things performance.Her coverage spans from the daily routines of top athletes like Michael Phelps and Coco Gauff to the latest cutting-edge science on building muscle to the rise of peptides, supplements, and GLP medications. She loves a deep dive into fitness subcultures, health companies, or the science behind managing and preventing disease, particularly early-onset cancers. Gabby has a background in investigative journalism (previously contributing research for an investigation on correctional healthcare for the New Yorker).In her free time, she likes lifting heavy, running fast, and playing roller derby for Gotham in New York City.Send story ideas and tips to glandsverk@bjinnox.com.Expertise/Interests
  • Longevity: how to dial in a daily routine to invest in long-term health, and what makes some of the longest-living people on earth active and vibrant as they age.
  • Performance science: training techniques for goals ranging from muscle-building (hypertrophy), general physical preparedness, endurance, and injury prevention, especially for fitness beginners. 
  • Cancer research: unpacking the science behind why certain cancers are on the rise in younger people, how it's affecting the world around us, and what we can do about it. 
  • Healthy eating: how to navigate conflicting and contradictory advice across trends like protein-maxxing, intermittent fasting, and the Mediterranean, Nordic, and MIND diets.
  • Medical weight loss: how emerging science around treatments like GLP medications are shaping the connections between food, weight, and health. 
  • Digital wellness: investigating how telehealth is changing access to healthcare, including through peptides, hormones, and direct-to-consumer lab tests. 
  • Strength sports, including Olympic weightlifting, powerlifting, Hyrox, and CrossFit. 
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