GLP-1 medications explained
What GLP-1 medicines such as Mounjaro (tirzepatide) and Wegovy (semaglutide) actually do, who NICE says they are for, how much weight loss to expect, and the side effects that matter.
Written by Professor Mohammed Mahdi Althaf
Medically reviewed by Professor Mohammed Mahdi Althaf, Consultant Nephrologist · 1 August 2026
Overview
GLP-1 receptor agonists (such as semaglutide and tirzepatide) mimic a naturally occurring gut hormone released after eating. They are recognized by the Association of British Clinical Diabetologists (ABCD) and the Association for the Study of Obesity (ASO) as transformative tools in metabolic health.
Why they are given
- Appetite Regulation: They signal the brain (hypothalamus) to increase satiety and reduce "food noise."
- Gastric Emptying: They slow the movement of food from the stomach, helping you feel full longer.
- Cardiorenal Protection: Beyond weight loss, they offer significant protection for the heart and kidneys.
The ABCD and ASO Perspective
- The Association of British Clinical Diabetologists (ABCD) emphasizes the importance of these medications in managing the "diabesity" epidemic.
- The Association for the Study of Obesity (ASO) advocates for a multidisciplinary approach, combining medication with nutritional and psychological support.
What to expect month by month
- Weeks 1-4: Minimal weight loss; focus on managing mild nausea and establishing routine.
- Month 3: Significant appetite reduction; first major weight check.
- Month 6: Formal reassessment of eligibility for continued treatment (NICE requirement).
Preparing for your appointment
Are these "cheating"?
No. They are medical treatments for a chronic disease (obesity), addressing biological drivers that diet and exercise alone often cannot overcome.
How long do I stay on them?
This is a long-term treatment. Stopping usually results in weight regain unless a sustainable maintenance plan is in place.
References
- Association of British Clinical Diabetologists (ABCD) Position on GLP-1 RA
- Association for the Study of Obesity (ASO) UK
- NICE TA1026: tirzepatide for managing overweight and obesity
- NICE TA875: semaglutide for managing overweight and obesity
This article is general patient information reviewed by a consultant nephrologist. It is not individual medical advice; treatment decisions are made at a face-to-face consultation.