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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Is Wegovy Stronger Than Mounjaro? What the Evidence Shows
Wegovy and Mounjaro are not directly comparable in terms of "strength" — they work differently and show similar average weight loss results in clinical trials. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whilst Wegovy (semaglutide) works through GLP-1 alone. Both are prescription-only weight management injections available in the UK through NHS specialist services or private prescribing. Individual results vary significantly, and the "stronger" option depends on your personal health needs and how your body responds. This guide explains the key differences to help you understand both medications in a UK context.
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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 Wegovy and Mounjaro Compare: Mechanism and Clinical Evidence
Wegovy is a once-weekly GLP-1 receptor agonist manufactured by Novo Nordisk. In the STEP-1 clinical trial, participants lost an average of 14.9% of their body weight over 68 weeks at the maximum dose of 2.4 mg. Mounjaro uses a dual mechanism — activating both GIP and GLP-1 receptors — and showed average weight loss of 20.9% at the maximum 15 mg dose in the SURMOUNT-1 trial over 72 weeks.
However, these trials had different designs, participant populations, and durations, making direct comparison complex. Some individuals respond better to GLP-1 alone (Wegovy), whilst others may see greater results with the dual GIP/GLP-1 approach (Mounjaro). The concept of "stronger" is misleading — both medications are effective, and efficacy is individual. Factors including your metabolism, adherence, diet, and exercise all influence real-world outcomes.
- Wegovy: GLP-1 only, up to 2.4 mg weekly
- Mounjaro: GIP + GLP-1, up to 15 mg weekly
- Average weight loss varies but both show clinically significant results
- Individual response differs between medications and between people
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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.
NHS Access and UK Prescribing Context for Both Medications
Both Wegovy and Mounjaro are available through the NHS via specialist tier 3 weight management services, though regional availability varies considerably. NICE has approved both medications for use within NHS specialist services for eligible adults. NHS access typically requires GP referral and assessment by a specialist team. Waiting lists in many areas are lengthy, sometimes extending to many months.
Alternatively, both medications are available privately through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber — this route offers faster access without NHS referral. Your GP or prescriber will assess which medication (if either) is appropriate based on your individual health, weight history, and any existing medical conditions. Ask your GP about local NHS availability or discuss private options with your healthcare provider.
- 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 medically stronger than Wegovy?
Not in a simple sense. Mounjaro showed higher average weight loss in clinical trials (20.9% vs 14.9%), but trials differed in design and duration. "Strength" depends on individual response — some people lose more weight with Wegovy, others with Mounjaro. Your body's response is what matters, not trial averages.
Can you switch from Wegovy to Mounjaro on the NHS?
Potentially, yes. If Wegovy hasn't provided adequate results or causes side effects you cannot tolerate, your NHS specialist team may consider switching to Mounjaro. Any medication switch must be managed by your prescriber — never self-switch. Discuss concerns with your NHS weight management service.
What are the main differences between the two medications?
Wegovy is a GLP-1 receptor agonist (once weekly, max 2.4 mg); Mounjaro activates both GIP and GLP-1 pathways (once weekly, max 15 mg). Wegovy has been available longer; Mounjaro is newer with dual mechanism. Both require weekly injections and clinical monitoring. Side effect profiles are similar but not identical.
Is Mounjaro available on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is available through NHS specialist tier 3 weight management services following NICE approval. Access varies by region and availability. You typically need GP referral to a specialist service. Private access is also available via online prescribing without NHS referral.
Which medication will work better for me — Wegovy or Mounjaro?
This cannot be predicted in advance and depends on your individual metabolism, health conditions, and how your body responds to GLP-1 and GIP signalling. Your GP or prescriber will assess your medical history and recommend the most appropriate option. Some people respond better to one than the other — your prescriber may suggest starting with one and reviewing results.
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.