Peptide YY vs Semaglutide
Written by Aaron CuhaReviewed Sep 2026
The short answer
Two different fullness signals. One is a gut hormone released after eating. The other is a type of drug built on a different gut hormone. PYY has been chased again and again as a drug, and held back again and again by nausea. That is worth knowing before you read any claim about it.
- Peptide YY people
- 12
- Peptide YY nulls
- 1
- Semaglutide people
- 42,363
- Semaglutide nulls
- 2
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
3 completed trials, 12 people given it
Dose
Approved titration: 0.25, 0.5, 1, 1.7 and 2.4 mg
0.25, 0.5, 1, 1.7 and 2.4 mg
The approved semaglutide ladder, in mg.
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
Peptide YYPeptide YY (PYY, including the circulating fragment PYY3-36)
Peptide YY is a gut hormone your body releases after meals, alongside GLP-1. Given by drip to 12 lean and 12 obese people, it cut how much they ate at a buffet by about 30 percent in both groups. The rat and mouse result it was built on failed when other labs tried to repeat it. Nausea kept it from becoming a drug.
Column B
SemaglutideSemaglutide (GLP-1 receptor agonist)
A once a week shot for type 2 diabetes and weight loss. It is approved, and big studies show it also lowers the risk of heart attack and stroke.
Side by side, on the facts we can check
| What we compare | Peptide YY | Semaglutide |
|---|---|---|
| Category | Metabolic | Metabolic |
| FDA status | Not FDA-approved. No PYY or PYY3-36 product is approved anywhere. Natural PYY3-36 has only been given to people in studies, by a slow drip into a vein or under the skin. | FDA-approved (Ozempic and Rybelsus for type 2 diabetes; the Wegovy shot, the Wegovy pill approved Dec 2025, and Wegovy HD 7.2 mg approved Mar 2026 for weight management) |
| Half-life | Not reported | ~7 days |
| Molecular weight | 11,145 Da precursor (97 residues, UniProt P10082); PYY(1-36) is residues 29 to 64 and PYY(3-36) residues 31 to 64 | 4,113.6 Da |
| How it works | In people, given by drip: PYY3-36 at normal after-meal levels makes people feel less hungry and eat less for hours. It lowers ghrelin, the hunger hormone. It works just as well in lean and obese people. In rats and mice, though this part is disputed: PYY3-36 cuts eating through a receptor called Y2. Mice without that receptor do not respond. It quiets the brain's hunger cells, called NPY cells. That frees up nearby fullness cells, called POMC cells. Full length PYY acts on several Y receptors. Trimming by DPP-4 makes it prefer Y2. PYY also slows how fast food leaves the stomach and moves through the gut. That is its older known job, as the gut's brake. | It switches on the GLP-1 receptor, a switch on cells that normally answers a gut hormone after you eat. That makes the body release insulin when blood sugar is high. It holds back glucagon, a hormone that raises blood sugar. It slows how fast the stomach empties. It also acts on the part of the brain that runs hunger, so people eat less. |
| Studies in people | 3 | 15 |
| Evidence | Limited: 3 completed trials, 12 people given it | Strong: 12 completed trials, 42,363 people given it |
| Legal status, US | Not approved; research use only | FDA-approved, prescription only |
Frequently asked questions
What is the difference between Peptide YY and Semaglutide?
Peptide YY: Peptide YY is a gut hormone your body releases after meals, alongside GLP-1. Given by drip to 12 lean and 12 obese people, it cut how much they ate at a buffet by about 30 percent in both groups. The rat and mouse result it was built on failed when other labs tried to repeat it. Nausea kept it from becoming a drug. Semaglutide: A once a week shot for type 2 diabetes and weight loss. It is approved, and big studies show it also lowers the risk of heart attack and stroke.
Which has stronger research evidence, Peptide YY or Semaglutide?
Each compound gets a band worked out from facts we counted, with the math shown. Peptide YY is Limited (3 completed trials, 12 people given it). Semaglutide is Strong (12 completed trials, 42,363 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Peptide YY and Semaglutide FDA-approved?
Peptide YY: Not FDA-approved. No PYY or PYY3-36 product is approved anywhere. Natural PYY3-36 has only been given to people in studies, by a slow drip into a vein or under the skin.. Semaglutide: FDA-approved (Ozempic and Rybelsus for type 2 diabetes; the Wegovy shot, the Wegovy pill approved Dec 2025, and Wegovy HD 7.2 mg approved Mar 2026 for weight management).
Related posts
Blog articles that cover Peptide YY or Semaglutide, newest first.
- Dispatch / Sep 27, 2026 / 8 minDispatch 001: Five Retatrutide Phase 3 Trials Have Finished And None Has Posted Results
- Metabolic / Sep 27, 2026 / 8 minTesofensine Is Not a Peptide: What It Is, the Trials, and the Heart-Rate Issue
- Longevity / Sep 27, 2026 / 12 minPeptides for Longevity: What the Evidence Actually Shows in 2026
- Metabolic / Sep 27, 2026 / 10 minOral GLP-1s in 2026: Wegovy Pill vs Foundayo (Orforglipron) vs Rybelsus, and What Is Coming
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.