How different peptide therapies may affect your body

November 18, 2025
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6
 mins read
WRITTEN BY
Nicole Pajer
MEDICAL REVIEWED BY
The Prenuvo Medical Group
Summary

Peptides are short chains of amino acids that help regulate processes like metabolism, immunity, and cell communication. Some, like GLP-1 agonists, are FDA-approved, while others remain experimental. Peptide therapies may support weight loss, muscle preservation, healing, and longevity, but research is limited, and risks like hormonal changes or side effects exist.

Peptides seem to be just about everywhere lately. They’ve really exploded in popularity with people using them for everything from weight loss to muscle preservation and faster healing. But many people are experimenting with these therapies without fully understanding what they actually do, how they interact with the body, and their potential risks. Here’s a deeper look at these trending treatments. 

What are peptides and how do they work?

Peptides are short chains of amino acids—the same building blocks that make up proteins. They typically contain anywhere from 2 to 50 amino acids that are linked together by chemical bonds called peptide bonds. Peptides play many roles and are responsible for many biochemical processes. Because they’re smaller, they can move around the body more easily and act quickly where needed. 

Your body makes peptides naturally within your cells. These are involved in all sorts of things behind the scenes, including: 

  • Helping your cells to communicate with each other: Peptides act like messengers, carrying signals that help your cells work together.
  • Immune defense: Some peptides serve as part of your body’s first line of defense, helping fight off harmful bacteria and viruses.
  • Metabolism and regulation: Hormones like insulin and glucagon are peptides that help control blood sugar and energy use.

Scientists have also learned how to develop synthetic peptides (lab made versions), which have been designed to mimic or enhance these natural functions in the body. Some of these peptides  were created to behave just like the natural peptides in your body, while others are modified to last longer in the body or to target very specific tissues. These synthetic peptides are the foundation of peptide therapy. 

Why are peptides becoming so popular?

Peptides are catching people’s attention for several reasons. Their ability to act in a targeted manner means they’re often able to provide the same benefits as traditional drugs or hormones and sometimes with fewer side effects. This can help minimize unintended effects on the rest of the system—for instance when you take ibuprofen for joint pain, it can sometimes upset the digestive tract or increase the risk of heart attack or stroke

Peptides are also versatile. GLP-1 agonists are being used to control blood sugar in type 2 diabetics and also to control appetite, which can lead to weight loss

Where does the research stand on peptides?

Peptide therapies are currently being used for a wide range of things from helping to reduce appetite to stimulating growth hormone release, balancing blood sugar, speeding up wound healing, and even optimizing the immune system. There are also many ongoing studies into new peptides and their future uses, as well as varying uses for the existing ones. Some of these peptide therapies have strong clinical evidence behind them, while others are still in early research. And there are some being used in longevity and wellness clinics without formal FDA approval.

Some of the more common peptide therapies

There are many different types of peptide therapies on the market today. Here are a few of the more common ones:

GLP-1 Receptor Agonists (Semaglutide, Tirzepatide): These peptides are perhaps the ones on this list you’ve heard of, as they have been widely embraced by several known people in the Hollywood scene. GLP-1 receptor agonists were originally developed to help manage type 2 diabetes and have shown effectiveness helping people with the condition. Once put into the body, whether as an injection or orally, GLP-1 antagonists mimic the actions of a hormone called glucagon-like peptide 1 (GLP-1). So when a person’s blood sugar begins to rise after a meal, this peptide causes the body to produce more insulin to offset it

Beyond their initial intention, GLP-1 receptor agonists have shown effectiveness in helping to regulate appetite and enhance insulin sensitivity, which can help to promote weight loss. Studies have shown people to have significant reductions in weight and waist circumference after taking these medications. 

This FDA-approved treatment has been associated with some side effects, which include: a hollowed look to the face, nausea, vomiting, diarrhea, and constipation. More serious and rarer side effects include pancreatitis, bowel obstruction, and gallstone attacks. 

Related: How weight loss drugs affect your entire body

Growth Hormone Secretagogues (CJC-1295, Ipamorelin): Taking this peptide therapy can help the body stimulate the release of its own growth hormone, which may aid in muscle preservation and recovery. Research has linked growth hormone secretagogues with the potential to improve lean body mass and reduce fat mass. This therapy is not currently FDA-approved but is sometimes used in wellness and longevity clinics. At the moment, there are limited peer-reviewed human studies on CJC-1295 or Ipamorelin and these are still being studied for their effectiveness and potential side effects. 

BPC-157 (Body Protection Compound-157): This synthetic peptide has shown potential in recovery and promoting tissue healing. Some research has suggested that it may enhance tendon and ligament healing, reduce inflammation, and support gastrointestinal health. BPC-157 is still considered to be in its experimental stages and is actually prohibited under the World Anti-Doping Agency (WADA) for athletes. The organization also warns that since it’s not approved for human clinical use by any global regulatory authority, it may lead to negative health effects including immunogenic reactions (antibodies), peptide impurities, and limited safety data for proposed routes of use.

Melanotan II: Melanotan II is a synthetic peptide that stimulates melanin production in your cells, which can mimic the effect of skin tanning. It comes in different forms, including nasal sprays or injections, sometimes referred to as “tan jab” or “tanning injections.” It’s trended on TikTok for being deemed the “Barbie drug” with influencers talking about how it’s given their complexions a “glow up” and some raving about how it’s a safer option for getting a tan than tanning beds. Some people have reported using it to increase their libido and sexual function. 

But Melanotan II has been linked to some serious side effects including kidney failure, nausea, skin flushing,  skin cancer, and potential cardiovascular issues. It’s not FDA approved and is illegal in many countries, including the United States. Some people are finding ways to purchase it but organizations like the FDA stress that not only is that not legal, it’s dangerous. 

Thymosin Alpha-1: Thymosin Alpha-1 is a peptide that plays a role in immune modulation by boosting T cell function and NK activity, which helps to fight infections, autoimmune disorders, and cancers. It has been studied for its potential to enhance immune responses and may have applications in treating infections and certain cancers. Thymosin Alpha-1 is currently not approved by the FDA and it is still being studied in ongoing clinical trials. It is being used in around 35 other countries like China to treat conditions such as chronic hepatitis B and C. Studies show it’s mostly well tolerated, with the most common side effects being flu-like symptoms and fatigue. 

Emerging peptides in longevity clinics: Some clinics are experimenting with newer peptides such as FOXO4-DRI, which is being studied for its potential ability to clear senescent cells—cells that have stopped dividing and accumulate with age. A build-up of these cells can contribute to inflammation and tissue dysfunction. 

Another peptide therapy currently in research stages is Epitalon, a synthetic peptide linked in early research to telomere activity and longevity. These compounds are not yet FDA-approved and most human evidence is still very limited. But they are some of the many areas of research scientists are doing to try to find uses for peptides in healthy aging. 

Risks to be aware of with peptides

While many peptides may be considered generally safe when used under medical supervision, there are risks attached to them that users should educate themselves on. For instance, some peptides that stimulate growth pathways in the body have raised some potential concerns about cancer. In particular, growth hormone–related peptides (like GHRPs or GHRHs) can increase IGF-1 levels, which some researchers have suggested have the theoretical potential to promote the growth of existing cancer cells. BPC-157 as mentioned above also carries this theoretical increased risk of cancer through a similar mechanism through Vascular endothelial growth factor (VEGF) stimulation. There haven’t been enough long-term human studies to causally link either of these to increased rates of cancer but it is a potential that some experts flag. 

Related: Early cancer detection screens aren’t just for high-risk people

Experimental peptides, like FOXO4-DRI or Epitalon, that are being used in longevity clinics have not been studied extensively in humans. So, their long-term safety remains unknown. 

And then there are the potential side effects of these peptide treatments, which can include everything from hormonal imbalances to injection-site reactions, fatigue, or even cardiovascular changes. 

There are also quality and sourcing concerns, as peptides obtained from unregulated sources may be mislabeled, contaminated, or falsified, which increases risks. And using non FDA approved peptides puts users in danger of the dangerous consequences of using them that government agencies warn of. 

The importance of monitoring your treatments

How a peptide therapy affects you depends on many individualized factors, like your health history, dosage, and duration of use. That said, you should only try peptide therapies under medical supervision. Educate yourself on the potential side effects, walk through them with your physician, and factor that into your decision-making as to whether or not you take them. If you start any therapies and notice side effects, make sure to report any new changes to your medical care team immediately.

While using peptides, it’s important to monitor what’s happening in your body and track how the therapies are working. Some changes may occur quietly, without obvious symptoms, and may only become apparent at later stages when conditions become more serious. Regular monitoring with blood work and a Prenuvo Scan can help detect any new developments and provide insight into how well a peptide therapy is performing or affecting the body. For example, a GLP-1 peptide might help reduce your waistline. But you won’t know if it’s reducing the dangerous visceral fat hidden behind your abdominal wall or preserving lean muscle without more information. A screening, like Prenuvo’s Body Composition Analysis can provide comprehensive health information such as detailed information about your muscle mass and how much visceral fat you may have.

Peptides may hold a lot of promise in anti-aging, immune function, and more. But there is still a lot about these treatments that are unknown. Before diving in, it’s important to educate yourself on the potential benefits and risks and make an educated decision with your healthcare team. 

Related: What happens when you combine whole body MRI and blood work?

Considering peptides? Schedule a call to learn more about how a Prenuvo Whole Body Scan and a Prenuvo Body Composition Analysis can give you a health baseline before starting or track your progress along the way.

FAQ

What are peptides and what do they do?

Peptides are short chains of amino acids that may help regulate key body processes such as metabolism, immune function, and tissue repair. Some occur naturally in the body, while others are synthetically made for therapeutic purposes.

Are peptide therapies safe?

Many peptides are generally considered safe when used under medical supervision, but side effects can include hormone imbalances, fatigue, or injection-site reactions. Some non–FDA-approved therapies carry more serious risks, including kidney issues and, theoretically, cancer. Experimental peptides have limited human data, so long-term safety remains unknown.

How can I monitor the effects of peptide therapy?

Peptide therapies should only be used under the supervision of a qualified medical professional. Regular blood work and imaging, such as a Prenuvo Scan, can help track how therapies are affecting your body and help detect any changes early—even those without obvious symptoms.

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