What Are GIP and GLP-1 — and Why Do They Matter on Mounjaro?

GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) are both incretin hormones — chemical signals released from the gut in response to eating. Each plays a distinct role, and understanding the difference between GIP and GLP-1 helps explain why targeting both is thought to be meaningful.

What GLP-1 does

GLP-1 is released after meals and acts on several areas of the body, including the brain, pancreas, and digestive tract. Its commonly described effects include stimulating insulin release, slowing the rate at which the stomach empties, and signalling a sense of fullness to the brain. Many people taking GLP-1 receptor agonists report a noticeable reduction in what is often called "food noise" — the persistent background pull of appetite or thoughts about food.

For a deeper look at this hormone on its own, see what GLP-1 is and how it works. You may also find it useful to read about what a GLP-1 receptor agonist is for broader context.

What GIP does

GIP is actually the more abundant of the two incretin hormones in the body. It also stimulates insulin secretion after meals. Researchers have observed that in people with obesity or type 2 diabetes, the body's natural response to GLP-1 is often reduced — but the response to GIP tends to remain more intact. Activating the GIP receptor is also associated with effects on fat tissue and energy balance, though the full picture of how this contributes is still an active area of scientific understanding.

To explore what the GIP receptor specifically means in the context of Mounjaro, this overview of GIP in Mounjaro goes into more detail.

Why the dual action matters

Because tirzepatide (the active substance in Mounjaro) acts on both GIP and GLP-1 receptors, it is described as a dual GIP and GLP-1 receptor agonist. The two pathways are thought to work in a complementary way — each reinforcing the appetite-regulating and metabolic effects of the other. It is worth noting that individual responses vary, and any questions about how this applies to your own treatment should be discussed with your prescriber or doctor.

Understanding the science behind GIP and GLP-1 is one thing — noticing how those mechanisms actually show up in your daily experience is another. That is where tracking becomes genuinely useful.

GLP Trackr's daily check-in lets you log food noise levels, appetite, energy, and mood each morning in around 30 seconds. Over time, the app's insights feature surfaces patterns in your own data — for example, whether your sense of fullness or food noise shifts around your weekly injection, or how sleep and appetite seem to relate for you specifically. These are the kinds of observations that can make a real difference when you bring them to a conversation with your prescriber.

The app also includes side-effect tracking, so if you notice nausea or digestive changes — commonly reported effects linked to slower gastric emptying — you can log them alongside your dose history and see how they change over time.

For a fuller picture of how Mounjaro works beyond the hormone level, the guide to how Mounjaro works covers the broader mechanism and what people on the medicine commonly experience.

GLP Trackr is available free on the App Store and Google Play, with a 7-day free trial — log your first week of check-ins and start seeing your own patterns take shape.

GLP Trackr provides general information and a tracking tool — it is not a substitute for advice from your prescriber or doctor. If you have questions about how your medication is working for you, or if you experience anything unexpected, speak with your healthcare professional.