If you’ve heard terms like GLP-1, BPC-157, CJC-1295, GHK-Cu, or NAD+ floating around the health and wellness space, you may be wondering: What exactly are peptides? Peptides are essentially short chains of amino acids—the same building blocks that make up proteins. Many peptides occur naturally in the human body and act as signaling molecules, helping cells communicate and influencing processes such as metabolism, appetite, hormone production, tissue repair, immune function, and more. Researchers have also developed peptide-based medications and synthetic analogues designed to mimic or modify these naturally occurring signals. Some are well-established FDA-approved medications, while others remain experimental or are being investigated in clinical and preclinical research. The Main Peptide Categories You’ll Hear About 1. Metabolic Peptides — GLP-1, GIP & Glucagon This is probably the most recognizable category right now. GLP-1 and related incretin-based therapies influence appetite, insulin secretion, blood sugar regulation, gastric emptying, and body weight. Examples include semaglutide, a GLP-1 receptor agonist, and tirzepatide, which targets both GIP and GLP-1 pathways. Research is continuing into compounds that target multiple metabolic pathways simultaneously, including GLP-1/GIP/glucagon signaling. 2. Growth Hormone–Related Peptides Another commonly discussed group includes peptides that interact with the body's growth hormone axis. You may hear names such as CJC-1295, ipamorelin, sermorelin, and tesamorelin. These compounds differ considerably in their mechanisms, evidence, and regulatory status, but generally involve signaling related to growth hormone secretion. 3. Tissue Repair & Regenerative Peptides Peptides such as BPC-157 and thymosin beta-4–related compounds are frequently discussed for their potential roles in tissue repair, inflammation, blood vessel formation, and recovery. This is an especially important area to separate hype from evidence: many popular “healing peptides” have interesting laboratory or animal research but far less human clinical evidence. 4. Immune & Thymic Peptides Peptides can also participate in immune signaling. Thymosin alpha-1, for example, has been studied for its effects on immune regulation and host defense. Other thymic peptides continue to be investigated for potential immunomodulatory applications. 5. Neurological & Cognitive Peptides Another emerging category includes compounds being researched for their effects on the nervous system, cognition, stress responses, and neuroplasticity. Semax and Selank are two names commonly encountered in this space, although research and regulatory approval vary significantly by country. 6. Skin, Hair & Cosmetic Peptides Peptides are also increasingly used in dermatology and cosmetic medicine. GHK-Cu (copper peptide) is one of the better-known examples and has been investigated for its potential effects on collagen, skin remodeling, wound healing, and hair biology. Peptides Are a Huge Category One of the biggest misconceptions is that “peptides” are a single type of therapy. They aren't. Insulin is a peptide. GLP-1 is a peptide. Oxytocin is a peptide. There are also neuropeptides, growth factors, gastrointestinal peptides, immune-related peptides, and countless other signaling molecules throughout the body. And importantly, not every peptide discussed online has the same amount of research behind it. Some peptide-based therapies have decades of clinical data and FDA approval, while others are still experimental. That distinction is exactly what we’ll explore in this community—what the research actually says, where the evidence is promising, and where we still have more questions than answers. Medical Disclaimer: This content is for educational purposes only and is not medical advice. Some peptides discussed may be investigational or not FDA-approved for human use.