Weight Loss Injections Explained: A Complete Patient Guide to GLP-1 Medications
What Are GLP-1 Weight Loss Injections?
GLP-1 (glucagon-like peptide-1) receptor agonists are a class of medications that have transformed the treatment of obesity over the last few years. Originally developed for type 2 diabetes, these injectable drugs have shown remarkable results in helping people lose significant amounts of weight — and keep it off.
The most commonly prescribed GLP-1 medications in the UK currently include:
- Semaglutide (Ozempic, Wegovy) — a weekly injection by Novo Nordisk
- Tirzepatide (Mounjaro) — a weekly injection by Eli Lilly that targets two hormones (GLP-1 and GIP)
- Liraglutide (Saxenda) — a daily injection also by Novo Nordisk
How Do They Work?
GLP-1 medications work in several ways that together reduce your appetite and help you eat less:
1. Slow stomach emptying — Food stays in your stomach longer, so you feel full for longer after eating.
2. Reduce appetite signals in your brain — They act on areas of the brain that control hunger, making you feel less hungry throughout the day.
3. Lower blood sugar — They stimulate insulin release after meals and reduce glucose production by the liver.
4. Improve insulin sensitivity — This is particularly helpful if you have prediabetes or type 2 diabetes.
Think of it this way: most people who struggle with their weight aren't lacking willpower — their hunger hormones are simply working against them. GLP-1 medications reset that hormonal imbalance.
What Results Can You Expect?
Clinical trials have shown impressive results:
| Medication | Average Weight Loss | Trial Duration |
|---|---|---|
| Semaglutide (Wegovy 2.4mg) | ~15% of body weight | 68 weeks (STEP trial) |
| Tirzepatide (Mounjaro 15mg) | ~20–22% of body weight | 72 weeks (SURMOUNT trial) |
| Liraglutide (Saxenda) | ~8% of body weight | 56 weeks |
Am I Eligible for GLP-1 Injections?
Eligibility for GLP-1 weight loss injections is typically based on:
- BMI of 30 or above (or BMI 27+ if you have a weight-related health condition such as high blood pressure, type 2 diabetes, or sleep apnoea)
- No personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia type 2 (MEN2)
- Not pregnant or breastfeeding
- No history of pancreatitis (inflamed pancreas)
How Are They Prescribed in the UK?
In the UK, GLP-1 medications are prescription-only. This means you need to be assessed by a qualified healthcare professional before they can be prescribed to you.
On the NHS: Wegovy (semaglutide) was approved for NHS use in 2023, but access remains limited through specialist weight management services. Waiting lists can be very long. Privately: Many patients choose to access GLP-1 medications through private independent prescribers, which is completely legal and often much faster. Private prescribers conduct the same medical checks as NHS services.GetClinic connects patients with fully qualified, regulated independent prescribers who can assess your eligibility and prescribe these medications safely if appropriate.
What Are the Side Effects?
The most common side effects are gastrointestinal:
- Nausea (very common, especially when starting or increasing your dose)
- Vomiting
- Diarrhoea or constipation
- Stomach pain or bloating
- Reduced appetite (this is also the intended effect)
- Gallstones (increased risk with rapid weight loss)
- Fast heartbeat or palpitations
- Very rare: pancreatitis — seek immediate medical attention if you have severe abdominal pain
How Are They Administered?
All currently available GLP-1 weight loss injections are self-injected. They come as pre-filled pens with a very fine needle (most people describe them as virtually painless).
- Ozempic / Wegovy / Mounjaro: Inject once a week, on the same day each week
- Saxenda: Inject once a day
Frequently Asked Questions
Will I need to be on these injections forever? This is individual. Some people reach their weight goals and are able to maintain their weight without medication. However, obesity is a chronic condition with a biological basis — many people find they regain weight if treatment is stopped. Your prescriber will discuss this with you. Can I drink alcohol while taking GLP-1 medications? Alcohol can increase the risk of low blood sugar (hypoglycaemia), especially if you also have diabetes. It can also worsen nausea. Moderate alcohol consumption is generally acceptable, but it's best to discuss with your prescriber. Are GLP-1 medications safe during pregnancy? No — these medications should be stopped at least 2 months before attempting pregnancy. If you become pregnant while on a GLP-1 medication, stop immediately and contact your GP. Can I take GLP-1 medications if I have type 2 diabetes? Yes — in fact, GLP-1 medications were originally developed for type 2 diabetes management. If you are already on diabetes medications, your prescriber will need to review and potentially adjust your existing treatment to avoid low blood sugar.How to Get Started
If you're interested in discussing weight loss injection treatment, the first step is a consultation with a qualified independent prescriber. They will:
1. Take a full medical history
2. Review your current medications
3. Discuss realistic goals and expectations
4. Recommend the most suitable medication and dose
5. Provide ongoing monitoring and support