Peptide Therapy: Potential Risks, Popular Uses, and What the Research Says

Written by: Sophia Schweiger
Reviewed by: Laura Kleiber, MS, RDN, LDN - North Hills Lead Dietitian

In Part 1 of our peptide series, we explored what peptides are, why they have become so popular, and the major ways they are being studied and marketed. While peptides represent an exciting area of emerging research, the growing popularity of these therapies has also created important questions about safety, effectiveness, and regulation.

For consumers, one of the most important distinctions to understand is the difference between what a peptide is biologically capable of doing, what early research suggests it might do, and what has actually been demonstrated to be safe and effective in humans.

For individuals considering peptide therapy, working with a registered dietitian can also provide an important nutrition perspective. Peptide therapy may influence appetite, metabolism, recovery, or other physiological processes; therefore, nutrition remains an important part of supporting health and achieving sustainable outcomes.

A Closer Look at Popular Peptide Categories

Recovery and Tissue Repair

Peptides such as BPC-157, TB-500, and GHK-Cu are frequently marketed for injury recovery, tissue repair, inflammation, skin health, and regeneration.

There is legitimate scientific interest in the biological processes these peptides may influence. However, much of the evidence remains preclinical, and human research is limited. For example, BPC-157 has received considerable attention for its potential role in tissue repair. However, current marketing claims can inflate perceptions of the peptide benefits, given the limited high-quality human evidence available.

The same principle applies to TB-500. Research involving thymosin-β4—a synthetic fragment of TB-500—has explored its role in tissue repair. However, virtually all published research on TB-500 has been conducted in animal models, leaving significant gaps in our understanding of its safety and effectiveness in humans.

GHK-Cu presents another important distinction. It is used in some cosmetic and topical products for skin-related purposes, while injectable versions and combinations such as “GLOW” stacks—commonly marketed as BPC-157 + TB-500 + GHK-Cu—raise additional concerns about product quality, sterility, immune reactions, and limited long-term safety data.

The takeaway: Promising biological mechanisms and early research warrant further investigation, as they do not yet establish these peptides as proven and safe recovery therapies for humans.

From a nutrition perspective, foundational factors such as adequate protein intake, energy availability, hydration, sleep, and appropriate recovery nutrition should also remain part of the conversation, particularly for individuals pursuing sports performance or recovery.

Hormone and Growth Signaling

Peptides that influence the GH/IGF-1 pathway deserve particular attention because they manipulate powerful hormonal signaling systems.

Examples include CJC-1295, ipamorelin, sermorelin, and IGF-1 products.

These peptides are commonly marketed for muscle growth, fat loss, recovery, sleep, and anti-aging. However, altering growth hormone and IGF-1 signaling can affect multiple systems throughout the body, including glucose regulation and fluid balance. The long-term effects of chronically manipulating these pathways also remain an important area of research.

For individuals interested in muscle growth, body composition, or athletic performance, a comprehensive approach to sports nutrition and personalized nutrition should consider the individual's training program, energy intake, protein intake, recovery, and overall health rather than focusing on a single intervention.

What About Tesamorelin?

Tesamorelin provides a useful example of why context and indication matter when it comes to peptide therapy.

Tesamorelin is FDA-approved for reducing excess abdominal fat in adults with HIV-associated lipodystrophy. Its approval does not mean that it has been established as a general anti-aging or weight-loss treatment. An FDA-approved peptide can still have a very specific medical purpose. The appropriate use of a medication depends on the individual, the condition being treated, and the available evidence.

Longevity, Reproductive, and Sexual Health Peptides

A number of peptides are marketed for longevity, hormone optimization, reproductive health, or sexual function.

Epitalon, for example, has been studied in the context of aging and cellular processes, but evidence remains limited. Kisspeptin has attracted scientific interest because of its role in reproductive hormone signaling and fertility. However, using it as a general “hormone optimization” therapy is not yet well established in the research.

PT-141 (bremelanotide) is another example where the distinction between marketing and medical use matters. Bremelanotide is FDA-approved for acquired, generalized Hypoactive Sexual Desire Disorder (HSDD) in premenopausal women, but it is not approved as a general vitality or sexual performance enhancer.

Incretin-Based Therapies and the GLP-1 Medications

GLP-1–based medications warrant a different discussion from many of the peptides marketed in wellness and performance spaces.

Semaglutide is a GLP-1 receptor agonist, while tirzepatide acts on both GIP and GLP-1 receptors. Retatrutide is a newer multi-receptor therapy being investigated for its effects on metabolic health and body weight.

These therapies have brought peptide biology into mainstream medical care, particularly because they can meaningfully influence appetite, food intake, blood glucose regulation, and body weight.

What happens to nutrition when appetite changes dramatically?

This is an immensely important question to consider when using GLP-1 medications for weight loss. For some individuals, reduced appetite can make it substantially easier to consume fewer calories. That may be part of the intended therapeutic effect, but it can also make it more difficult to consistently meet nutritional needs. This is where personalized nutrition counseling with a registered dietitian can become particularly valuable.

A dietitian can help an individual prioritize:

• Adequate protein
• Appropriate energy intake
• Hydration
• Fiber and micronutrient intake
• Regular meal structure
• Food quality and nutritional density
• Resistance training and recovery
• Management of nutrition-related GI symptoms

The goal is not simply to help someone “eat less.” The goal is to help them eat appropriately for the body they are trying to support while their appetite and food intake are changing.

For someone taking a GLP-1 medication, working with a GLP-1 dietitian can be particularly useful when reduced appetite, GI symptoms, or changes in food intake make it difficult to meet nutritional needs. Additionally, these medications can influence the biological drivers of appetite and metabolism, but they do not independently create a balanced diet, adequate protein intake, resistance-training stimulus, or sustainable eating pattern.

A personalized nutrition approach can help account for the individual's goals, food preferences, activity level, symptoms, medical history, and changing appetite rather than applying a one-size-fits-all approach.

What Are the Biggest Concerns With Peptide Therapy?

1. Limited Long-Term Research

As mentioned above, many popular peptides lack large, long-term human trials evaluating their safety and effectiveness.

We may have preliminary evidence suggesting that a peptide influences a particular biological pathway, but that does not tell us everything we need to know about long-term outcomes.

Important unanswered questions include:

• How effective is it in humans?
• What populations benefit most?
• What are the appropriate clinical uses?
• What happens with long-term use?
• What happens when it is combined with other therapies?

2. Product Quality and Sterility

Another important concern with peptide products is product quality. Peptides marketed outside of approved medical use may be sold as “research use only” products, which can make it difficult to determine whether the product contains the stated peptide, the labeled amount, or other substances.

Manufacturing and handling practices also matter, particularly for products intended for injection. Injectable peptides need to be manufactured and handled under conditions that minimize contamination and maintain sterility. If these standards are not met, contamination, impurities, or inaccurate dosing can introduce health risks that are separate from the peptide’s intended biological effects.

3. Stacking Multiple Peptides

Peptide “stacks” combine multiple compounds in an attempt to produce several effects at once.

Although this may seem appealing, combining therapies makes it more difficult to determine:

• Which compound is responsible for a side effect present
• Whether the compounds interact in a negative way
• Whether combining them increases risk of adverse effects

4. Manipulating Hormonal Pathways

Peptides that influence growth hormone and IGF-1 signaling require particular caution because these pathways affect growth, metabolism, and other physiological processes.

Individuals considering these therapies should discuss their medical history with an appropriate healthcare professional, particularly if they have concerns involving:

• Blood glucose regulation
• Cardiovascular health
• Hormonal disorders
• Cancer history
• Pregnancy or plans for pregnancy

What Should You Ask Before Considering a Peptide?

If you are considering peptide therapy, start with a few important questions:

• Is this peptide FDA-approved for my specific condition?
• Is there strong human research supporting the use I am considering?
• Where is the product coming from, and how is its quality verified?
• Am I working with a qualified healthcare professional who can monitor its effects?
• Have I addressed the foundational factors that influence my goal?

That last question is particularly important from a nutrition perspective. If the goal is improved recovery, body composition, energy, or healthy aging, foundational factors such as nutrition, physical activity, sleep, and adequate recovery should not be overlooked in pursuit of a more advanced intervention.

For individuals using GLP-1–based medications, this can mean paying particular attention to whether reduced appetite is also resulting in inadequate protein, energy, fluids, fiber, or micronutrients.

This is an area where nutrition counseling with a registered dietitian can help translate broad recommendations into a practical eating strategy that fits the individual's needs.

What Is the Dietitian's Role?

Registered dietitians do not prescribe peptide therapy or provide peptide dosing recommendations. However, they can still play an important role in supporting clients who are considering or already using these therapies.

A dietitian can help assess:

• Protein and energy intake
• Nutritional adequacy
• Recovery and fueling
• Metabolic health
• Body composition goals
• Lifestyle factors affecting health and performance

For individuals using GLP-1 medications, a GLP-1 dietitian can also help identify potential nutrition gaps related to appetite changes, gastrointestinal symptoms, meal frequency, protein intake, hydration, and overall dietary adequacy.

When medication or peptide therapy is being considered, nutrition care can also be coordinated with the client's physician or other qualified healthcare professionals.

The goal is not to dismiss emerging therapies, but to help clients approach them with an informed and evidence-based perspective.

Where Is Peptide Research Headed?

Peptide research is rapidly evolving, and future studies may help clarify where these therapies fit into medicine, performance, and wellness.

Important areas of future research include:

• Long-term safety outcomes
• Appropriate clinical applications
• Standardized dosing guidelines
• Product quality and purity standards
• Understanding which individuals may benefit most

As science continues to advance, peptides may become an important part of personalized healthcare. For now, informed decision-making requires separating promising research from marketing claims and considering the evidence behind each individual therapy.

‍

Whether you’re just beginning your health journey, looking to optimize your nutrition and overall health, hoping to improve your sports performance, or proactively working to prevent future disease, get matched with your Case Specific dietitian in just 5 clicks at casespecificnutrition.com/match.

Our team provides individualized nutrition counseling throughout the Greater Pittsburgh area, with dietitians serving clients in East Liberty, Mt. Lebanon, the North Hills, Plum, Robinson, and Upper St. Clair–Peters Township, as well as in Erie, Altoona, and Raleigh.

Looking for more practical, evidence-informed nutrition and wellness guidance? Check out The Case Specific Podcast, where CEO and founder Andrew Wade, along with other CSN dietitians, discuss nutrition, health, fitness, and wellness; break down the science behind common nutrition questions; and share practical strategies you can use in everyday life. Listen to The Case Specific Podcast on our website, watch on YouTube, or listen on Spotify.

For more nutrition tips, educational content, team updates, and the latest from Case Specific Nutrition, follow us on Instagram and connect with us on LinkedIn.

References

• Huberman Lab. “Benefits & Risks of Peptide Therapeutics.” 2024.
• U.S. Food & Drug Administration. “Certain Bulk Drug Substances May Present Significant Safety Risks.”
• World Anti-Doping Agency. Prohibited List 2025.
• FDA Access Data: Tesamorelin (Egrifta WR) and Bremelanotide (Vyleesi) Prescribing Information.