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How do GLP-1 drugs actually work in the body?
The science of GLP-1, GIP and the incretin drugs explained in plain English, with sources cited.
How Does Mounjaro Work? Mechanism, Dosing, and Ozempic ComparisonMounjaro (tirzepatide) is a once-weekly injection that activates two gut-hormone receptors, GIP and GLP-1, while drugs like Ozempic act on GLP-1 alone. Through GLP-1 signaling it stimulates insulin release, suppresses glucagon, slows the stomach, and cuts appetite; its half-life is about 5 days.How Does Semaglutide Work in the Body?Semaglutide is a lab-made copy of the gut hormone GLP-1 that binds GLP-1 receptors to stimulate insulin, lower glucagon, slow stomach emptying, and reduce appetite in the brain. Three chemical changes give it a half-life of about one week, so one injection lasts seven days.How Does Zepbound Work? GIP and GLP-1, Explained SimplyZepbound (tirzepatide) activates two gut-hormone receptors at once, GIP and GLP-1, which is why it is called a dual agonist. It starts at 2.5 mg once weekly for 4 weeks and can go up to a 15 mg weekly maintenance dose.How Long Does Semaglutide Stay in Your System?Semaglutide has an elimination half-life of approximately 1 week, so it remains in circulation about 5 weeks after the last Ozempic dose and 5 to 7 weeks after the last Wegovy 2.4 mg dose. Here is what that means for starting, stopping, pregnancy planning, and surgery.How Long Does Tirzepatide Stay in Your System? (Mounjaro, Zepbound)Tirzepatide has a half-life of about 5 days, so after your last weekly shot the drug keeps working its way out of your blood for roughly 25 days — about five half-lives. Here's what the labels and FDA review actually say.Oral Semaglutide vs Injection: Pills, Pens, and What Actually DiffersOral semaglutide (Rybelsus, Ozempic, Wegovy tablets) and injectable semaglutide (Ozempic, Wegovy) are the same molecule with different rules: pills are daily on an empty stomach with a 30-minute wait; shots are weekly with no food limits. OASIS 4: the 25 mg pill gave −13.6% weight loss vs −2.2% placebo.Semaglutide vs Tirzepatide: Which Works Better for Weight Loss?Semaglutide (Ozempic, Wegovy) targets one receptor; tirzepatide (Mounjaro) targets two. In the only head-to-head trial, tirzepatide produced −20.2% body weight vs −13.7% for semaglutide at 72 weeks.Tirzepatide and Birth Control: Does It Affect the Pill?Yes — the Mounjaro and Zepbound labels say tirzepatide can affect absorption of oral contraceptives, and advise switching to a non-oral method or adding a barrier method for 4 weeks after starting and after each dose increase.What Is GIP? The Second Incretin Behind TirzepatideGIP (glucose-dependent insulinotropic polypeptide) is a gut hormone that, like GLP-1, triggers insulin release after meals. Tirzepatide activates both receptors and beat semaglutide in trials; in a Phase 1b trial in type 2 diabetes, a GIP-only drug raised insulin sensitivity 33.1% over 12 weeks.What Is GLP-1? The Hormone Behind Ozempic, ExplainedGLP-1 stands for glucagon-like peptide-1, a gut hormone the body makes that regulates insulin secretion, carbohydrate metabolism and appetite. Drugs like Ozempic are GLP-1 receptor agonists that switch on the same receptor; incretins explain two-thirds or more of the insulin response to oral glucose in healthy people.Who Discovered GLP-1? The People Behind Ozempic and WegovyNo single person discovered GLP-1. The work spans more than 30 years across several labs, and the 2024 Lasker Prize went to Joel Habener, Svetlana Mojsov, and Lotte Bjerre Knudsen. Ozempic is not made from Gila monster venom — that was exenatide, approved in 2005.