Is PYY the same as NPY?

No, though they are related and the names invite confusion. NPY is a central neuropeptide that stimulates feeding. PYY is a gut hormone whose active fragment suppresses it, acting at a receptor expressed on NPY neurons. They belong to the same peptide family and do opposite things.

Does eating more release more PYY?

Release is described as proportional to the calorie content of the meal, so in that specific sense yes. That proportionality is what makes it a signal about the meal rather than about the fed state generally.

Why is a 33% reduction in intake not enough for a drug?

Because it was measured over 24 hours during an infusion. Body weight is determined over months, and compensatory responses - increased hunger, reduced energy expenditure - accumulate over that timescale and are invisible in a one-day study.

Is PYY related to anything sold here?

No. PYY and its analogues are research and clinical-development molecules; none is licensed, and none is supplied on this site. This article is reference material about a signalling system, not about a product.

GLP-1 & Incretin Science

PYY(3-36): The Satiety Signal Scaled to the Meal

JMWritten & reviewed by Jack Muncaster · Founder, UK PeptidesLast reviewed 2026-08-232 cited sources

Peptide YY is a gut hormone released after a meal in proportion to its calorie content. Its active fragment PYY(3-36) is a Y2 receptor agonist that reduces food intake, and in one human study reduced 24-hour intake by 33% at ordinary postprandial concentrations.

Key facts

Active fragment: PYY(3-36)
Receptor: NPY Y2 receptor
Where the receptor sits: Presynaptically on NPY neurons of the arcuate nucleus
Release stimulus: Postprandial, proportional to meal calorie content
Enzyme producing the active form: DPP-4
Human result: 33% reduction in food intake over 24 hours on infusion
Genetic control: No anorectic effect in Y2r-null mice
Key paper: Batterham RL et al., Nature 2002 (PMID 12167864)

The hormone that measures the meal

Most appetite signals report a state - how much fat is stored, how long since the last meal. PYY reports an event. It is released from the gastrointestinal tract after eating, and Batterham and colleagues describe that release as being in proportion to the calorie content of the meal. That makes it a quantitative postprandial signal rather than a binary one, which is a meaningfully different kind of information for the brain to receive and a reason the hormone attracted so much interest as a target.

The DPP-4 twist

PYY is secreted as PYY(1-36) and cleaved to PYY(3-36) by dipeptidyl peptidase-4, the same enzyme that inactivates GLP-1 within minutes of its release. The two truncations do opposite things. Cleaving GLP-1 destroys it. Cleaving PYY converts it from a form with broad NPY-receptor activity into one that is selective for the Y2 receptor - which is the receptor through which the anorectic effect runs. The same enzymatic step is a termination signal for one gut hormone and an activation step for another. Anyone who has read that DPP-4 simply degrades gut peptides has half the picture.

How the circuit works

The Y2 receptor is described as a putative inhibitory presynaptic receptor and is highly expressed on the NPY neurons of the arcuate nucleus - a region accessible to peripheral hormones. NPY neurons drive feeding. POMC neurons, which sit adjacent, suppress it, and the two populations inhibit each other. Batterham and colleagues showed that PYY(3-36) inhibits the electrical activity of NPY nerve terminals, which releases the adjacent POMC neurons from inhibition and activates them. So the hormone reduces feeding twice over from a single action: it silences the drive and, by silencing it, unleashes the brake. Peripheral administration increased c-Fos immunoreactivity in the arcuate nucleus and decreased hypothalamic Npy messenger RNA, and injecting PYY(3-36) directly into the arcuate nucleus inhibited food intake on its own.

The genetic control, and why it matters

PYY(3-36) inhibited food intake in mice, but not in Y2r-null mice. That is the experiment that converts an observed effect into an identified route. Without it, a hormone that reduces feeding could be doing so through any of a dozen mechanisms including simple malaise. With it, the anorectic effect is shown to require the specific receptor the model proposes. This is the same logical structure as the PepT1 knockout in the KPV literature and the GDF15-null mice in the metformin work, and it is the single most informative experiment a mechanistic paper can run.

The human number, and its limits

In humans, infusion of PYY(3-36) at concentrations matching those seen normally after a meal significantly decreased appetite and reduced food intake by 33% over 24 hours. That is a large effect and it was achieved without pharmacological concentrations - the point of the design was that the exposure was physiological. It is also an acute infusion study measuring intake over one day in a laboratory setting, which is a long way from sustained weight change. Acute intake studies and chronic weight trials disagree routinely, and a compound that reduces one meal's intake by a third may do nothing measurable to body weight over a year.

Why PYY has not become a drug

It has been pursued repeatedly and has not produced a licensed weight-management medicine. The reasons illustrate a general problem with this class of target. Native PYY(3-36) has a short circulating life, so it needs engineering to be dosed practically. Nausea has been dose-limiting in clinical work, which is the recurring tax on hindbrain and hypothalamic appetite signals. And the acute effect on a single day's intake has repeatedly failed to translate into the sustained divergence in body weight that a weight-management indication requires. PYY analogues remain in development, including in combination with incretins, on the reasoning that partial engagement of several pathways may achieve more than full engagement of one.

Extended research context

The GLP-1 & Incretin Science deep dive

Deep dive: the two routes to a bigger effect

Every compound trying to beat GLP-1 alone has taken one of two routes. The first adds more receptors from the same hormone family — GIP in tirzepatide, GIP and glucagon in retatrutide. The second adds a non-incretin satiety hormone, which in practice means amylin: CagriSema combines cagrilintide with semaglutide, and amycretin engages both receptors from one molecule. Both routes work, because they recruit signalling pathways that do not fully overlap. Neither has escaped the constraint that binds all of them, which is that gastrointestinal tolerability worsens as effect size grows.

Deep dive: why a percentage is not a result

The most-quoted numbers in this field are the least comparable. REDEFINE 1 reported 22.7% and 20.4% for the same compound in the same trial — the first among participants who adhered to treatment, the second across everyone randomised. TRIUMPH-1 reported 28.3% in an uncomplicated obesity population while TRIUMPH-3 reported up to 22.6% in adults with established cardiovascular disease, using the same compound. Before any two figures can be compared they have to match on estimand, population, duration, comparator and whether the number is placebo-adjusted. Most published comparisons match on none of them.

Deep dive: what happens after the trial stops

Every headline figure describes weight while treatment continues. The STEP-1 extension found that a year after semaglutide was stopped, participants had given back roughly two-thirds of what they lost, moving from 17.3% mean reduction to a net 5.6% — though average weight remained below baseline and nearly half stayed at least 5% down. Meta-analysis puts regain at around 0.8 kg per month. This is why maintenance studies such as TRIUMPH-6 matter more to the field's future than another two points of peak reduction.

Research applications

▸Comparing incretin and amylin compounds on a like-for-like basis
▸Interpreting estimands, thresholds and placebo-adjusted figures in trial reports
▸Tracking the obesity pipeline across sponsors and jurisdictions
▸Understanding receptor pharmacology behind GLP-1, GIP, glucagon and amylin
▸Distinguishing licensed medicines from investigational compounds

Handling checklist

✓Identify which estimand a quoted percentage comes from before citing it
✓Check the trial population and baseline BMI against the comparison you are making
✓Confirm the duration and whether the reduction curve had plateaued
✓Read discontinuation rates alongside efficacy figures
✓Verify every NCT identifier against ClinicalTrials.gov rather than secondary reporting

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Comparing headline percentages across different trials

Fix: Population, duration, estimand and comparator all differ; the numbers are not interchangeable.

✗ Quoting the larger of two figures from the same trial

Fix: Name the estimand. Efficacy and treatment-policy answer different questions.

✗ Treating peak reduction as a durable outcome

Fix: Substantial regain follows cessation across the class; peak figures describe a maintained state.

✗ Assuming an oral route means a weaker mechanism

Fix: Route and receptor count are independent. Orforglipron is weaker because it hits one receptor, not because it is a tablet.

✗ Reading investigational compounds as available treatments

Fix: Most of this pipeline holds no authorisation anywhere; mazdutide is approved only in China.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Frequently asked questions

Is PYY the same as NPY?: No, though they are related and the names invite confusion. NPY is a central neuropeptide that stimulates feeding. PYY is a gut hormone whose active fragment suppresses it, acting at a receptor expressed on NPY neurons. They belong to the same peptide family and do opposite things.
Does eating more release more PYY?: Release is described as proportional to the calorie content of the meal, so in that specific sense yes. That proportionality is what makes it a signal about the meal rather than about the fed state generally.
Why is a 33% reduction in intake not enough for a drug?: Because it was measured over 24 hours during an infusion. Body weight is determined over months, and compensatory responses - increased hunger, reduced energy expenditure - accumulate over that timescale and are invisible in a one-day study.
Is PYY related to anything sold here?: No. PYY and its analogues are research and clinical-development molecules; none is licensed, and none is supplied on this site. This article is reference material about a signalling system, not about a product.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

Written and reviewed by

Jack Muncaster · Founder, UK Peptides

Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.

How we write and check this content Report a factual error in this article

More GLP-1 & Incretin Science articles

Popular across the research hub

One flagship guide from every other research category — keep exploring.

← Back to Forum