GLP-1 injectables such as Wegovy and Mounjaro have recently made headlines as game changers in the weight loss industry. Originally developed for type 2 diabetes, these medications are now widely used for weight loss thanks to their ability to reduce appetite and support weight reduction.
Although effective for many, they are not a one-size-fits-all solution. For some, weight loss surgery remains a more predictable and durable long-term option.
In this guide, we answer five of the most common questions about GLP-1 injectables, explain their benefits and limitations, and explore why Transform is one of the UK’s most trusted providers of weight loss surgery.
What Are GLP-1 Injectables and How Do They Work?
GLP-1 (glucagon-like peptide-1) is a hormone that regulates blood sugar and appetite. GLP-1 treatments mimic this hormone, slowing digestion and helping you feel fuller for longer. Mounjaro also works on a second hormone, GIP (glucose-dependent insulinotropic polypeptide).
They are usually delivered as a weekly injection in the stomach, arm, or thigh. Weight loss can vary considerably depending on lifestyle, side effects, and dosage. Not everybody will be able to tolerate the medication.
It may also be difficult to maintain weight loss when medication is discontinued, as not all of these treatments are licensed for weight maintenance.
1. How Effective Are They for Weight Loss?
Studies show that patients using Wegovy can lose 10–15% of their body weight over a year, particularly when paired with diet and exercise.
The challenge lies in long-term maintenance. Once treatment stops, appetite commonly returns and weight regain follows. GLP-1 treatments do not change the digestive system permanently; their impact ends when the injections stop.
2. Do They Have Side Effects?
Most patients tolerate GLP-1 treatments but may experience side effects initially. These can include:
- Nausea or vomiting
- Constipation or diarrhoea
- Fatigue or headaches
Less common but more serious risks include pancreatitis, gallbladder issues, and kidney strain, which is why a complete medical evaluation is essential before starting treatment.
3. How Long Do You Have to Stay on Them?
GLP-1 treatments are intended for long-term use, until you reach your goal weight or a normal BMI. Mounjaro is licensed for weight maintenance and can therefore be used in the long term.
However, stopping the medication usually results in an increased appetite and likely weight gain. For many, the prospect of lifelong medication is a significant emotional and financial commitment.
By contrast, surgery provides permanent anatomical changes, simplifying long-term weight management.
4. Who Is Eligible for GLP-1 Injectables?
Eligibility generally includes:
- People with type 2 diabetes struggling with glucose control
- Adults with a BMI of 30 or higher
- Adults with a BMI of 27 or higher with at least one weight-related complication such as hypertension or sleep apnoea
On the NHS, access is prioritised for those with diabetes or severe obesity plus complications. Privately, prescriptions are available, but cost and access can still pose challenges.
For formal criteria, see the NICE guidance.
5. How Do GLP-1 Injectables Compare to Surgery?
While weight loss injections help reduce weight, weight loss surgery is widely regarded as the gold standard.
Surgery eliminates the need for lifelong injections and monthly payments, offers excellent excess weight loss, and provides better long-term sustainable results.
GLP-1 treatments:
- Suppress appetite and assist with weight loss while in use.
Surgery:
- Physically reduces stomach size or re-routes the digestive tract.
- Alters hunger hormones.
- Provides a long-term solution to weight management.
Surgical Options Include:
- Gastric Sleeve – Removes up to 80% of the stomach, reducing hunger and promoting ~60% excess weight loss.
- Gastric Bypass – Reduces stomach size and re-routes intestines, combining smaller portions and reduced absorption to help patients lose ~70% excess weight.
- Gastric Band – Places an adjustable band around the stomach to limit food intake, typically leading to 44–55% excess weight loss.
Weight loss varies by individual, but in many cases surgical outcomes exceed current recommendations.
When Surgery May Be the Better Choice
GLP-1 injectables can be helpful, but surgery may be more appropriate when:
- Long-term results are desired
- Your BMI is above 30
- You have weight-related health issues to improve or resolve
- You do not meet the criteria or cannot tolerate the injections
- You prefer a one-time investment rather than indefinite monthly costs
Beyond numbers on the scales, surgery often transforms lives. Patients like Sacha embraced change through Transform’s weight loss surgery, experiencing not just weight reduction but also renewed confidence and vitality.
The Transform Weight Loss Surgery Experience
At Transform, care is tailored to your needs, with expert surgeons and a full aftercare package:
- Patient Advisor Appointment – Explore options and get answers to your questions.
- Surgeon Consultation – Meet your surgeon and discuss your chosen procedure in detail.
- Nurse Consultation – A comprehensive review to prepare you for surgery.
- Dietetic Consultation – Pre- and post-surgery guidance from our dietitians.
- Surgery Day – Procedures last 1–3 hours, usually with an overnight stay (same-day discharge for gastric band).
- Recovery – Light activity in 1–2 weeks; full recovery in 4–6 weeks.
- Aftercare – Ongoing support from nurses and dietitians, plus:
- 24/7 helpline
- Patient support groups on Facebook
- Access to our Transform Weight Loss Hub with articles, recipes, and meal plans.
- 24/7 helpline
GLP-1 injectables are a significant advancement in medical weight management, offering short-term results for many. However, their side effects, cost, and reliance on continuous use make surgery a more reliable option for lasting weight loss.
At Transform, we focus on safe, personalised care that supports your journey from consultation to recovery and beyond.
Book your free consultation today and take the first step towards a healthier, happier you.
Medically reviewed by Sue Norton, Head of Weight Management
Clinical Dietetics Team for Transform Weight Loss
Last Reviewed September 4th 2025
