Polypeptide Y, also called peptide YY, is a gut hormone that affects appetite and satiety. Learn what it does, how it works, and what research says.
Polypeptide Y, also known as peptide YY (PYY), is a naturally occurring hormone made in the gut that helps regulate appetite and food intake. It is released after you eat and signals fullness to the brain. Polypeptide Y is not a skincare ingredient or a dietary supplement; it is a peptide your body produces on its own.
What Is Polypeptide Y?
Peptide YY is a 36-amino acid polypeptide. If you are asking what is a polypeptide, it is simply a short chain of amino acids linked by peptide bonds. Polypeptide Y belongs to the pancreatic polypeptide family, which also includes pancreatic polypeptide (PP) and neuropeptide Y (NPY).
Scientists first identified peptide YY in the 1980s. It gets its name from the tyrosine residues at both ends of the molecule. The polypeptide structure of PYY allows it to bind to specific receptors in the brain and gut.
There are two main forms of PYY: PYY1-36 and PYY3-36. The shorter form, PYY3-36, is the most active for appetite control. Most research focuses on PYY3-36 because it crosses the blood-brain barrier more efficiently.
How Polypeptide Y Affects Appetite and Digestion
After a meal, L-cells in the ileum and colon release PYY into the bloodstream. The level of PYY rises within 15 to 30 minutes and stays elevated for several hours. PYY then travels to the brain, where it binds to Y2 receptors in the hypothalamus.
Activation of Y2 receptors reduces hunger and slows gastric emptying. This means food stays in your stomach longer, which can make you feel full. Some research suggests that people with obesity may have lower PYY levels, but the relationship is complex.
Protein-rich meals tend to trigger the largest PYY release. Fat also stimulates PYY, while carbohydrates have a weaker effect. This is one reason high-protein diets may help with satiety.
Polypeptide Y Compared to Other Appetite Hormones
Several hormones work together to control hunger and fullness. The table below compares polypeptide Y with three other well-known appetite signals.
| Hormone | Main Source | Effect on Appetite | Key Notes |
|---|---|---|---|
| Polypeptide Y (PYY) | L-cells in the ileum and colon | Reduces appetite | Released after eating; slows gastric emptying |
| Ghrelin | Stomach | Increases appetite | Highest before meals; often called the hunger hormone |
| Leptin | Fat cells | Reduces appetite | Signals long-term energy stores; resistance can occur in obesity |
| GLP-1 | L-cells in the small intestine | Reduces appetite | Also slows gastric emptying; target of some diabetes drugs |
PYY and GLP-1 both reduce appetite, but they act through different receptors. Ghrelin is the only one of these hormones that increases hunger.
Polypeptide Y in Medical Research
Researchers have studied PYY as a potential treatment for obesity. In some trials, intravenous or intranasal PYY reduced calorie intake in both lean and obese participants. However, polypeptide Y is not FDA-approved for human use as a drug. It is also not available as a dietary supplement.
Bariatric surgery, such as gastric bypass, often raises natural PYY levels. This may partly explain why many patients feel less hungry after surgery. Still, more studies are needed to confirm long-term effects.
Polypeptide Y belongs to a larger polypeptide group of gut hormones that researchers continue to investigate. If you are considering any treatment that claims to target PYY, talk with a healthcare professional first.
Polypeptide Y vs. Skincare Polypeptides
It is easy to confuse polypeptide Y with the polypeptides used in cosmetics. Skincare products like a polypeptide serum or a polypeptide eye cream contain different peptides, such as signal peptides or carrier peptides. These are designed to support skin appearance, not to regulate appetite.
Popular products like Drunk Elephant Protini Polypeptide Cream use a mix of synthetic peptides. Those peptides are not the same as peptide YY. Polypeptide Y is a gut hormone, while cosmetic polypeptides are made in a lab for topical use.
If you are looking for skin benefits, cosmetic peptides are a separate category from metabolic hormones like PYY. Some people also search for a polypeptide calculator to estimate peptide dosages in research settings. That kind of tool is not meant for human dosing and should not be used for self-treatment.
Key Takeaways About Polypeptide Y
- Polypeptide Y (peptide YY) is a gut hormone that reduces appetite and slows digestion.
- It is released after eating, especially after protein-rich meals.
- Polypeptide Y is not a dietary supplement or an FDA-approved medication.
- Skincare polypeptides, such as those in a polypeptide serum, are different from peptide YY.
- Always consult a healthcare professional before using any product that claims to affect PYY.
Frequently Asked Questions
What does polypeptide Y do in the body?
Polypeptide Y, or peptide YY, is a hormone that reduces appetite and slows the movement of food from the stomach to the intestines. It is released after meals and helps you feel full. It works by binding to Y2 receptors in the brain.
Is polypeptide Y available as a supplement or medication?
No, polypeptide Y is not available as a dietary supplement and is not FDA-approved as a medication for human use. It is a naturally occurring hormone, and researchers have studied it experimentally for obesity. Any product claiming to contain PYY as a supplement should be viewed with caution.
Are the polypeptides in skincare products the same as polypeptide Y?
No, skincare polypeptides are synthetic or plant-derived peptides designed for topical use on the skin. Polypeptide Y is a gut hormone involved in appetite regulation. They share the word polypeptide but have completely different functions and structures.
This page provides educational research information and does not replace medical advice, diagnosis, or treatment.