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 10mg vs Wegovy — What's the Difference?
Mounjaro 10mg and Wegovy are both prescription-only GLP-1-based weight loss injections available in the UK, but they work differently and have distinct clinical profiles. If you're exploring weight management options, understanding how these two medications compare — including their mechanisms, trial results, and suitability — can help you have an informed conversation with your GP or prescriber about which might be right for your individual circumstances. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses, and consult your BMI using our free BMI calculator to understand your starting point.
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Calculate Your BMI Instantly
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.
Clinical Trial Data and Mechanism Differences
Mounjaro (tirzepatide) works via a dual mechanism — it activates both GIP and GLP-1 hormone pathways simultaneously. The SURMOUNT-1 clinical trial showed average weight loss of approximately 15% at the 5mg dose, 19.5% at 10mg, and 20.9% at the maximum 15mg dose over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) activates the GLP-1 pathway only. The STEP-1 trial demonstrated average weight loss of approximately 14.9% at the maximum 2.4mg dose over 68 weeks with the same lifestyle support.
- Mounjaro's dual mechanism may result in slightly greater average weight loss, though individual responses vary significantly
- Wegovy has longer clinical trial data (STEP programme includes multiple trials)
- Both require a reduced-calorie diet and physical activity for maximum benefit — medication alone is not sufficient
- Neither medication is insulin; both are receptor agonists that mimic natural hormone effects
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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.
Choosing Between Mounjaro 10mg and Wegovy
Both medications require a prescription following a clinical assessment from a UK-licensed prescriber. Your prescriber will consider your medical history, current medications (particularly diabetes treatments and oral contraceptives), and individual health profile to determine which is more suitable.
- Mounjaro 10mg is mid-range dosing — it may be appropriate if lower doses (5mg) haven't achieved target weight loss or if your prescriber believes dual GIP/GLP-1 activation suits your needs
- Wegovy may be preferred if you have specific contraindications to Mounjaro or if your prescriber judges single GLP-1 activation sufficient for your goals
- Both are available through NHS specialist tier 3 weight management services (availability varies by region) or via private online prescribing following clinical assessment
- Track your progress using our free progress tracker once you begin treatment
- 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.
Is Mounjaro 10mg more effective than Wegovy?
Clinical trials showed Mounjaro achieved slightly higher average weight loss than Wegovy (19.5% vs 14.9%), but individual results vary considerably. Effectiveness depends on your personal response, adherence, diet, and exercise. Your prescriber will assess which suits your specific health profile.
What's the difference between Mounjaro and Wegovy mechanisms?
Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways. Wegovy is a GLP-1 agonist only. The dual mechanism in Mounjaro may contribute to slightly greater appetite suppression for some people, though both work by reducing hunger and supporting feeling fuller sooner.
Can I switch from Wegovy to Mounjaro 10mg?
Yes, switching between medications is possible but requires your prescriber's approval and supervision. Approximate dosing equivalents exist (Wegovy 1.7mg ≈ Mounjaro 10mg), but the switch must be managed by your healthcare provider with careful monitoring.
Which medication is available on the NHS?
Both Mounjaro and Wegovy are NICE-approved for NHS specialist weight management services, but regional availability varies significantly. Many areas have substantial waiting lists. Both are available privately through online prescribing following clinical assessment. Your GP can refer you to tier 3 services in your area.
What's the cost difference between Mounjaro 10mg and Wegovy in the UK?
Private costs vary by provider and dose. Mounjaro costs roughly £150–£250 per month depending on dose; Wegovy ranges from approximately £129–£200 monthly. NHS prescriptions follow standard prescription charges. Ask your prescriber or pharmacy for current pricing in your area.
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.