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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How to Pronounce Mounjaro and Compare It With Wegovy
Mounjaro is pronounced "MOUN-jah-ro" with the active ingredient tirzepatide pronounced "tir-ZEP-a-tide." If you're considering weight management treatment in the UK, you may have heard both Mounjaro and Wegovy mentioned. While both are prescription-only GLP-1-based injections licensed for weight management, they work differently and have distinct clinical trial outcomes. Understanding how to say the name correctly is a small first step—understanding how they actually differ is more important for informed conversations with your GP or prescriber.
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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 and Wegovy Work Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two separate hormone pathways. This dual mechanism may help regulate appetite more effectively than single-pathway medications. Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating a single pathway.
- Mounjaro: dual GIP + GLP-1 mechanism, once-weekly injection, maximum dose 15 mg
- Wegovy: GLP-1 only, once-weekly injection, maximum dose 2.4 mg
- Clinical trial data (SURMOUNT for Mounjaro, STEP for Wegovy) shows Mounjaro achieved an average weight loss of approximately 20.9% at the highest dose, while Wegovy achieved approximately 14.9%—though individual results vary significantly
- Both require a reduced-calorie diet and increased physical activity alongside the medication for best results
The difference in mechanism explains why dosing schedules differ and why clinical trial results show variations. However, which medication is more suitable for you depends entirely on your individual health profile, medical history, and prescriber assessment—not just on published averages.
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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
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Which Medication Is Right for You?
Both Mounjaro and Wegovy are prescription-only medicines that require a clinical assessment before being prescribed. Your GP or licensed prescriber will evaluate your BMI, weight-related health conditions, current medications, and medical history to determine which—if either—is appropriate for you.
Neither medication is inherently "better" across all patients. Some people respond better to one mechanism than the other. Wegovy may be suitable for those seeking a single-pathway GLP-1 treatment, whilst Mounjaro's dual mechanism may appeal to others. Access in the UK is available through NHS specialist weight management services or private online prescribing following clinical consultation.
Use our free GLP-1 weight loss calculator above to explore potential weight loss projections, and discuss results with your prescriber before making any decisions. Individual outcomes depend on adherence, lifestyle factors, and personal physiology.
- 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.
How do you pronounce Mounjaro correctly?
Mounjaro is pronounced "MOUN-jah-ro" (rhymes with "mañana"). The active ingredient, tirzepatide, is pronounced "tir-ZEP-a-tide." Your GP or pharmacist can also demonstrate the correct pronunciation if you're unsure.
What's the main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist (two hormone pathways), whilst Wegovy is a GLP-1 receptor agonist only (single pathway). This difference in mechanism may account for variations in weight loss outcomes between the two medications, though both require clinical assessment to determine suitability.
Is Mounjaro more effective than Wegovy for weight loss?
Clinical trials showed Mounjaro achieved higher average weight loss (20.9% vs 14.9%), but individual results vary greatly. Effectiveness depends on your personal response, adherence, lifestyle changes, and overall health. Your prescriber will recommend the most suitable option for your specific circumstances.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between medications must be managed by your prescriber. There is no official conversion chart—your GP or pharmacist will assess whether a switch is appropriate and how to manage it safely. Never stop or change medications without professional guidance.
Are Mounjaro and Wegovy available on the NHS in the UK?
Both are licensed in the UK and available through NHS specialist tier 3 weight management services, though regional availability varies significantly. Private access is available through GPhC-registered online pharmacies following an online clinical assessment. Waiting lists for NHS services can be lengthy in many areas.
Ready to take control of your weight loss journey?
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