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Basics

What are GLP-1 medicines? A plain-English guide

By the Steadie team · Updated · 2 minute read

The short version

  • GLP-1 medicines copy a gut hormone that signals fullness and slows the stomach.
  • Semaglutide (Wegovy, Ozempic) and tirzepatide (Mounjaro) are the most common in the UK.
  • They reduce appetite while you take them; appetite usually returns after you stop.

How they work

GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after eating. It tells your brain you've had enough, slows how quickly your stomach empties and helps control blood sugar. GLP-1 medicines copy it and last much longer, so appetite stays lower.

Tirzepatide also acts on a second hormone signal, GIP. Both are weekly injections.

The medicines you'll hear about

  • Wegovy: semaglutide, licensed for weight management.
  • Ozempic: semaglutide, licensed in the UK for type 2 diabetes.
  • Mounjaro: tirzepatide, licensed for weight management and type 2 diabetes.
  • Saxenda: liraglutide, an older daily injection.

Wegovy, Ozempic and Saxenda are trademarks of Novo Nordisk; Mounjaro of Eli Lilly. Steadie isn't connected with either company and doesn't give advice about medication.

Why the year after matters

Because these medicines work while you take them, appetite and weight often return after stopping. That's why NICE says people should get at least a year of support afterwards. See coming off a GLP-1 and what happens when you stop.

Common questions

What's the difference between semaglutide and tirzepatide?

Semaglutide acts on the GLP-1 signal; tirzepatide acts on both GLP-1 and GIP. Both reduce appetite and are taken as weekly injections.

Sources

  1. NHS: semaglutide (Wegovy, Ozempic)
  2. NHS: tirzepatide (Mounjaro)
  3. NICE technology appraisal TA875: semaglutide for managing overweight and obesity
  4. NICE technology appraisal TA1026: tirzepatide for managing overweight and obesity
  5. NICE quality standard QS212, statement 6: wraparound care alongside medicines for weight management

This guide is general information, not medical advice. Steadie never gives advice about medication, doses or stopping treatment: talk to your prescriber, GP or pharmacist about those. In an emergency, call 999. Read how we write guides in our editorial policy.