Definition
GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after you eat. It helps release insulin, signals fullness and slows the stomach. GLP-1 medicines copy this hormone and make its effect last for days instead of minutes.
GLP-1 is one of the two main “incretin” hormones. Cells in the lower gut release it when food arrives, and it tells the pancreas to release more insulin while blood sugar is high and less glucagon, the hormone that raises blood sugar. GLP-1 receptors also sit in brain areas that regulate appetite. The labels describe GLP-1 as a physiological regulator of appetite and calorie intake.
Your own GLP-1 is gone almost as soon as it is made. The Saxenda label puts its half-life at 1.5 to 2 minutes, because the enzyme DPP-4 breaks it down. That is why drug makers built longer-lasting versions: semaglutide is 94% similar to human GLP-1 but binds to albumin and resists DPP-4, so it lasts about a week. See GLP-1 receptor agonist and half-life and steady state.
On a GLP-1 medicine, the hormone signal is stronger and it never switches off between meals. That explains both sides of the experience: less hunger and quieter food thoughts, and a slower gut that can bring nausea, constipation, burping or diarrhea. At GLP-1 SOS, almost every question we answer traces back to this one hormone acting on the gut and the brain.
In the Lab
- How long before a GLP-1 starts working (appetite and weight)
- Still hungry on a GLP-1: is it normal and what does it mean?
- Why a GLP-1 causes diarrhea (and why it alternates with constipation)
- How long nausea lasts after a GLP-1 injection
From the people behind the Lab
You do not have to figure this out alone.
GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas like GLP-1 SOS Daily Gut Relief, designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Sources (4)
- Incretin hormones: Their role in health and disease. Diabetes, Obesity and Metabolism, 2018.
- Mechanisms of Action and Therapeutic Application of Glucagon-like Peptide-1. Cell Metabolism, 2018.
- Saxenda (liraglutide) injection, Prescribing Information. Novo Nordisk, revised February 2026.
- Wegovy (semaglutide) injection and tablets, Prescribing Information. Novo Nordisk / FDA, revised June 2026.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.
