The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Mounjaro UK Comparison — How It Compares to Other Options
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist approved for weight management in the UK. If you're considering weight loss treatment, you may wonder how Mounjaro compares to other options available in the UK. This guide explains the key differences between Mounjaro and alternative weight loss approaches, including other prescription injections, lifestyle changes, and NHS pathways. Understanding your options helps you make an informed decision with your GP or prescriber about what might suit your health needs and circumstances.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Mounjaro Compares to Other Weight Loss Injections
In the UK, three main prescription weight loss injections are licensed: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro is unique because it activates two hormone pathways—GIP and GLP-1—whereas Wegovy targets GLP-1 only. Clinical trials showed Mounjaro users lost an average of 15–21% of body weight, compared to around 15% with Wegovy. Both are prescription-only medicines requiring clinical assessment. Mounjaro is delivered as a once-weekly KwikPen injection, starting at 2.5 mg and escalating to a maximum of 15 mg. Saxenda is a daily injection with a different dosing schedule. Individual results vary significantly, and the choice depends on your health profile, lifestyle, and prescriber recommendation. Try our GLP-1 weight loss calculator above to explore projected outcomes at different doses of either medication.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
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Mounjaro vs NHS and Private Access Routes in the UK
Access to Mounjaro in the UK differs depending on whether you pursue NHS or private routes. NHS access is through specialist tier 3/4 weight management services, typically requiring GP referral and assessment. Availability varies significantly by region (ICB), and waiting lists can be lengthy in many areas. Private access is available through GPhC-registered online pharmacies following a clinical consultation—no NHS referral required. Costs range from approximately £129–£320 per month depending on your dose. Both routes require a UK-licensed prescriber to assess your eligibility based on BMI, health conditions, and medical history. Check your BMI using our free BMI calculator to understand where you sit on NHS eligibility thresholds, and discuss your options with your GP.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What's the main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy targets GLP-1 only. This dual mechanism may explain why Mounjaro users in clinical trials achieved slightly higher average weight loss (15–21% vs 15%), though individual results vary. Both are prescription-only once-weekly injections available in the UK.
Can I get Mounjaro on the NHS in the UK?
Mounjaro is available through NHS specialist weight management services (tier 3/4), but access depends on your BMI, health conditions, and local NHS capacity. Many regions have significant waiting lists. Your GP can refer you to your local weight management service to check eligibility.
Is Mounjaro the same as Ozempic?
No. Mounjaro contains tirzepatide (dual GIP/GLP-1), while Ozempic contains semaglutide (GLP-1 only). Ozempic is approved for type 2 diabetes, not weight loss. Wegovy is the licensed weight management version of semaglutide. Always check which medication your prescriber recommends.
How long does it take to see weight loss results with Mounjaro?
Weight loss typically becomes noticeable around weeks 4–8 as your dose increases. Most significant loss occurs over 12–20 weeks as you reach maintenance doses. Results depend on diet, activity level, and individual metabolism. Track your progress using our free progress tracker.
What happens if I stop taking Mounjaro?
Weight regain can occur after stopping Mounjaro, as appetite-suppressing effects wear off. Long-term weight management typically requires sustained medication use alongside diet and activity changes. Discuss discontinuation plans with your prescriber to develop a transition strategy.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.