In 2022 to 2023, 64% of adults in England were estimated to be overweight or living with obesity. The first line treatment, according to NHS guidelines, is a focus on behavioural changes i.e. increasing physical activity and improving dietary choices. Only after these efforts have proved unsuccessful, or if there are other comorbidities, are pharmacological interventions considered. Despite the NHS guidance, many people are turning to weight loss injections to help manage their weight. Currently this is often obtained privately, though NHS England is currently undergoing consolation for a phased launch of Tirzepatide injections.
There are currently two main drugs used for weight loss; semaglutide (WeGovy/Ozempic) and tirezpatide (Mounjaro). These are administered as a once weekly injection.
Semaglutide acts as a glucagon-like peptide-1 (GLP-1) agonist. GLP-1 is a hormone that is released from the small intestine after food consumption. GLP-1 has several roles in the body, including triggering insulin release from the pancreas and blocking glucagon secretion. Both of these actions reduce blood glucose levels, making GLP-1 agonists effective managing type 2 diabetes. In addition to reducing blood glucose, GLP-1 release increases the feeling of satiety. This feeling of fullness reduces the food consumption of users leading to weight loss.
Tirzepatide acts as a duel GLP-1 agonist and as a Glucose-dependent insulinotropic peptide (GIP) agonist. GIP also stimulates insulin production and can work alongside GLP-1 to suppress the appetite by activating satiety pathways regulated by the central nervous system.
As GLP-1 receptors mimic the action of a peptide produced in the GI tract, the most common side effects are nausea, vomiting and diarrhea. These side effects are dose dependent so a gradual increase in dose is recommended. Once a patient decides to stop using the injections there is a risk they could regain some of the weight they lost. It is recommended that users of these medications also make lifestyle changes to maintain their weight loss.
Sources
Office for Health Improvement & Disparities, Obesity Profile: short statistical commentary May 2024
NICE Clinical Guideline, Obesity: identification, assessment and management
NICE, Consultation on NHS England proposals for a phased launch of obesity injection
Ricardo J. Samms, Matthew P. Coghlan, Kyle W. Sloop, How May GIP Enhance the Therapeutic Efficacy of GLP-1, Trends in Endocrinology & Metabolism, Volume 31, Issue 6, 2020, Pages 410-421
Wafa Latif; Katerina J. Lambrinos; Preeti Patel; Rolando Rodriguez, Compare and Contrast the Glucagon-Like Peptide-1 Receptor Agonists (GLP1RAs), Treasure Island (FL): StatPearls Publishing; 2024 Jan
https://www.ncbi.nlm.nih.gov/books/NBK572151/ Assessed and Endorsed by the MedReport Medical Review Board