Which GLP-1 Is Best for Weight Loss? (UK Comparison Guide)

According to a study published in BMC Medicine, around 4.9 million British adults are estimated to have recently used or expressed interest in using glucagon-like peptide-1 (GLP-1) or dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) receptor agonist medications for weight loss. There are different versions of these medications, which raises the question: which is the best?

Mounjaro (tirzepatide) currently shows the strongest average weight loss results in clinical trials. However, this doesn’t mean that it's the best choice for everyone. Your budget, body mass index (BMI), medical history, lifestyle, side effects, and treatment goals determine the best treatment for you.

This guide compares the UK-approved GLP-1 medications, explaining how they work, how much weight people may lose, and when each option may be suitable.

Key Takeaways

GLP-1 medications reduce appetite and help control blood sugar, making weight loss easier.
Mounjaro shows the highest average weight loss, but it’s not the best choice for everyone.
Wegovy and Saxenda are effective alternatives, with different dosing and results.
The right option depends on your goals, budget, and medical history.
Curely offers a flexible, clinically guided way to access treatment in the UK.

What Are GLP-1 Medications?

GLP-1 medications are prescription treatments that can support weight loss when used alongside lifestyle changes, such as eating a reduced-calorie diet and regular exercise. Most GLP-1 medications are weight loss injections.

GLP-1 stands for glucagon-like peptide-1. It’s a natural hormone your body releases after eating to help control appetite, digestion, and blood sugar. GLP-1 agonists mimic that effect, helping you feel fuller for longer and making it easier to eat less.

Some of these weight loss injections also affect other hormones. For example, Mounjaro contains the active ingredient tirzepatide, a dual agonist that acts on GLP-1 and GIP.

How GLP-1 Medications Work for Weight Loss

These treatments can help people lose weight because they:

• Reduce appetite
• Slow digestion
• Help you feel satisfied after smaller meals
• Support blood sugar control
• Reduce cravings or make them easier to manage

The UK's Medicines and Healthcare products Regulatory Agency (MHRA) recognises Saxenda, Mounjaro, and Wegovy injection as licensed GLP-1 receptor agonists (RA) for weight management in people with obesity or overweight with a weight related health condition in the UK.

However, the agency warns that people should use these weight loss injections only for licensed medical reasons, not for cosmetic weight loss. The three recommended injection sites for GLP-1s are the stomach/abdomen, thighs, and upper arms.

Best GLP-1 Medications in the UK

There are three main GLP-1 medications used for weight management in the UK: Mounjaro, Wegovy, and Saxenda.

Mounjaro (Tirzepatide)

Mounjaro is a weekly injection containing the active ingredient tirzepatide. It's a dual-action treatment because it acts on GLP-1 and GIP receptors.

According to the phase 3 double-blind clinical trial published in the New England Journal of Medicine, adults with obesity lost an average of 19.5% to 20.9% of body weight on higher tirzepatide doses. This makes Mounjaro the strongest weight-loss medication in the UK.

Other benefits of Mounjaro include:

• Lowering Blood Sugar Levels: Highly effective at lowering HbA1c (Glycated Haemoglobin) levels and managing Type 2 diabetes.
• Heart Health: Reduces the risk of major cardiovascular events, such as heart attacks and strokes.
• Reduces Liver Fat: Reduces fat and inflammation in the liver.
• Treats Sleep Apnoea: Reduces the number of times breathing stops during sleep.
• Reduces Insulin Resistance: Improves the body’s ability to process glucose, which is particularly beneficial for conditions like PCOS.
• Eliminates Food Noise: Suppresses cravings and obsessive thoughts about eating.
• Kidney Protection: Helps slow the progression of chronic kidney disease.

Wegovy (Semaglutide)

Wegovy contains semaglutide, the same active ingredient in Ozempic. It's a once-weekly injection used to treat obesity. Wegovy works by acting on appetite receptors in the brain, helping you feel fuller and experience fewer food cravings.

STEP 1 clinical trials published in the New England Journal of Medicine showed that semaglutide 2.4mg led to 14.9% reduction in body weight.

Besides weight loss, Wegovy offers the following benefits:

• Heart Protection: It is the first weight-loss drug specifically licensed to reduce the risk of heart attack, stroke, and cardiovascular death by 20% in people with heart disease.
• Reduced Inflammation: It lowers C-reactive protein (CRP) levels, a key marker of systemic inflammation that leads to chronic diseases.
• Liver Health: Doctors are now using Wegovy to treat MASH (liver inflammation and scarring) by reducing liver fat.
• Blood Pressure & Cholesterol: It helps lower systolic blood pressure and improves good cholesterol (HDL) while lowering bad cholesterol (LDL) and triglycerides.
• Sleep Quality: It reduces the severity of obstructive sleep apnoea (OSA), helping you breathe more consistently through the night.

Saxenda (Liraglutide)

Saxenda is a daily injection that contains the active ingredient liraglutide. It's an older GLP-1 option and may be suitable for some people. However, it's less convenient than weekly injection options.

The SCALE Obesity and Prediabetes trial showed Liraglutide 3mg led to an average body weight loss of around 8% after 56 weeks.

Other benefits of Saxenda include:

• Prevents Diabetes: Prevents prediabetes from turning into full type 2 diabetes by helping your body keep blood sugar at a healthy level.
• Helps the Heart: Lowers the risk of heart attack or stroke by keeping your blood vessels healthier.
  Fixes Fatty Liver: Helps remove excess fat that accumulates in the liver.
• Clears Skin and Balances Hormones: Can help clear acne and make periods more regular by stabilising blood sugar levels in women with PCOS.
• Lower Blood Pressure: Helps your blood flow more easily, reducing pressure on your heart.
• Better Cholesterol: Lowers LDL in your blood and can help raise HDL.
• Safe for Teens: It's one of the only weight-loss medicines that doctors have tested and approved for teenagers (ages 12+).

Comparison Table of GLP-1 Treatments in the UK

Which GLP-1 Is Best for Weight Loss Results?

Mounjaro is the best for average weight loss results. Clinical trials show that it produces the highest percentage of average weight loss. Its dual action on GLP-1 and GIP may explain why people often lose more weight than with other treatments.

The National Institute for Health and Care Excellence (NICE) recommends tirzepatide for managing overweight and obesity in eligible adults, with a healthy diet and increased physical activity.

It's important to note that the best treatment for you may not be Mounjaro. Instead, it depends on factors such as your medical history, budget, and routine.

Mounjaro vs Wegovy vs Saxenda

Weight Loss Effectiveness

Based on clinical trials, the average weight loss is highest with Mounjaro, followed by Wegovy and then Saxenda.

That does not mean everyone gets the same result. Factors such as your initial body weight and eating habits affect how much weight you may lose.

Dosing & Convenience

Mounjaro and Wegovy are weekly injections, but Saxenda is a daily medication. Some people find it easier to manage a weekly treatment. It's especially good if you travel often or have a busy lifestyle.

Side Effects

The most common side effects of these medications are:

• Feeling sick
• Diarrhoea
• Constipation
• Stomach pain
• Tiredness
• Reactions at the injection site

The severity of these side effects can be different for everyone, even when taking the same medication. Also, more severe side effects are rare, but they can happen. You should seek urgent medical advice if you develop the following symptoms:

• Severe Stomach Pain (Pancreatitis): Severe pain in your upper stomach that spreads to your back may be a sign of acute pancreatitis or an inflamed pancreas.
• Gallbladder Problems: Sudden, severe pain in the upper right side of your belly, often with yellowing of the skin or eyes (jaundice).
  Severe Allergic Reaction: Swelling of the face, lips, or tongue, and difficulty breathing.
• Hypoglycaemia (Low Blood Sugar): If you feel shaky, sweaty, confused, or dizzy, your blood sugar might be too low.
• Vision Changes: Sudden changes in your eyesight, especially if you have type 2 diabetes.
• Mental Health Changes: Feeling unusually depressed or having thoughts of hurting yourself.
• Severe Dehydration: You might need IV fluids to protect your kidneys if you are vomiting or have diarrhoea that won't stop.

You can also check the patient information leaflet for more information on the side effects of the individual medications.

Cost in the UK

Mounjaro costs about £145–£330 per month, while Wegovy costs £90–£350 per month. Branded Saxenda can cost £160 – £250 per month, depending on how many pens you need to reach the 3.0mg daily dose.

Costs vary between providers and doses because most people need treatment for several months. The best-value treatment balances:

• Clinical suitability
• Expected weight loss
• Side effect tolerance
• Support from healthcare providers
• Flexibility if you need to pause or change dose

Curely offers UK-licensed weight loss injections with a quick online consultation and clinical support. We can help you choose a treatment that fits your needs at an affordable price.

Eligibility Requirements for GLP-1RAs

All patients who want to use GLP-1 medications must meet one of the following requirements:

• A BMI of 30 or above (obesity)
• A BMI of 27 or above (overweight) with a weight-related health condition such as high blood sugar levels, high blood pressure, or high blood fat levels.

GLP-1 treatments are not suitable for:

• People with a Healthy BMI: Those with a BMI below 27 (or below 30 without a weight-related health condition).
• Pregnant or Breastfeeding Women: These medications are not currently cleared for use during pregnancy or while nursing.
• People with a History of Certain Cancers: Specifically, those with a personal or family history of Medullary Thyroid Carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
• People with Severe Gastrointestinal Issues: Particularly those with inflammatory bowel disease or gastroparesis (paralysed stomach).
• People with a History of Pancreatitis: Most clinicians will exclude anyone who has had acute or chronic pancreatitis.
• People with Type 1 Diabetes: These medications are specifically for type 2 diabetes or chronic weight management.
• Under 18s: While some limited paediatric licenses exist (such as Saxenda for ages 12+), most GLP-1s are not for minors.
• People with Severe Renal (Kidney) Impairment: Depending on the specific medication, advanced kidney disease may be a contraindication.

Are There Any Non-Oral Forms of GLP-1 Medications in the UK?

The main GLP-1 medications for weight management in the UK are non-oral. Some GLP-1 medicines are available as oral tablets, but only for diabetes treatment. For example, Rybelsus (semaglutide) is a daily oral GLP-1 receptor agonist authorised in the UK to treat adults with type 2 diabetes.

Injections are currently the key licensed options for weight loss. Also, there is no widely available generic version of these branded weight loss injections in the UK.

People who prefer tablets to injections should consider approved weight loss pills. For example, Xenical (branded Orlistat) is a prescription-only weight-loss pill that helps obese individuals lose weight by preventing about a third of the fat you eat from being absorbed into your body. Alli is a daily pill with the same effect that's available over the counter.

Get GLP-1 Medications in the UK with Curely

The National Health Service (NHS) provides access to GLP-1 medications only if you meet specific criteria. For example, NHS England recommends tirzepatide for eligible adults living with obesity who also have weight-related health problems such as dyslipidaemia or cardiovascular disease. Unfortunately, there is a long waiting list for these medications through the NHS.

Curely can be a faster route. With our services, you complete a short online health questionnaire, select medication, and receive discreet delivery to your home or workplace. No in-person GP visits, doctor appointments, or pharmacy queues.

We focus on flexibility, so you can pause or adjust your dose. Curely can also help you switch from one GLP-1 medication to another if you previously struggled with results.

You’ll have access to ongoing support from a healthcare team. Explore all our weight loss treatments today.

FAQs

Which GLP-1 Is Most Effective for Weight Loss?

Mounjaro is the most effective GLP-1 receptor agonist for weight loss based on current clinical trials. However, effectiveness depends on your dose, medical history, side effects, and lifestyle changes.

Is Mounjaro Better Than Wegovy?

Mounjaro may lead to greater average weight loss than Wegovy, but that does not mean it's better for everyone. Curely can help you compare suitability based on weight loss goals and cost.

How Much Weight Can I Lose With GLP-1 Treatment?

It depends on the medication and your response. Clinical trials show people lost around 20% with Mounjaro on higher doses, around 15% with Wegovy, and around 8% with Saxenda. You may lose more or less than these averages depending on how you respond to treatment.

Are GLP-1 Injections Safe?

GLP-1 medications are licensed for specific medical uses, but they are not suitable for everyone. They can cause severe side effects, which is why you should only use them under clinical supervision.

Can I Switch Between GLP-1 Medications?

Sometimes, but only with guidance from a healthcare professional. Switching between GLP-1 medications needs care because doses are not directly interchangeable. We can help you determine if you need to switch medications or get a higher/lower dose.

Do I Need A Prescription for GLP-1 Medicines in the UK?

Yes. GLP-1 medications for weight management are prescription-only. A qualified healthcare professional must check your eligibility before you can start treatment.

Conclusion

Mounjaro delivers the highest weight loss, making it the best GLP-1 treatment in terms of average results. However, it may not be the best for everyone due to factors such as response and cost. The right choice depends on your goals, budget, lifestyle, and medical history.

Always start with a proper clinical assessment to find the best GLP-1 treatment for you. Curely is here to help; complete a quick online consultation, and we'll get back to you with the best personalised support.

Reference List

• Jastreboff, Ania M., et al. “Tirzepatide Once Weekly for the Treatment of Obesity.” New England Journal of Medicine, vol. 387, no. 3, 4 June 2022, pp. 205–216.
• News Medical. “News-Medical.” News-Medical, 8 Jan. 2026.
• NICE. “Overview | Tirzepatide for Managing Overweight and Obesity | Guidance | NICE.” Nice.org.uk, NICE, 23 Dec. 2024.
• Pi-Sunyer, Xavier, et al. “A Randomized, Controlled Trial of 3.0 Mg of Liraglutide in Weight Management.” New England Journal of Medicine, vol. 373, no. 1, 2 July 2015, pp. 11–22.
• Wilding, John P. H., et al. “Once-Weekly Semaglutide in Adults with Overweight or Obesity.” The New England Journal of Medicine, vol. 384, no. 11, 10 Feb. 2021, pp. 989–1002. PubMed.