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 Golden Dose vs Wegovy: What's the Difference?
The "golden dose" refers to the effective maintenance dose where most weight loss benefits occur with manageable side effects. For Mounjaro (tirzepatide), this is typically around 10 mg weekly, whilst Wegovy (semaglutide) reaches its maximum at 2.4 mg weekly. Both are prescription-only medicines requiring UK clinical assessment. This guide compares the two, explaining the trial data behind each and how your GP or prescriber might help you choose. Individual results vary significantly, and the right medication depends on your personal health profile.
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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.
Clinical Trial Data: SURMOUNT vs STEP Results
Mounjaro (tirzepatide) was tested in the SURMOUNT-1 trial at multiple doses. At 10 mg weekly, participants lost an average of approximately 19.5% of body weight over 72 weeks alongside reduced-calorie diet and increased physical activity. At the maximum 15 mg dose, average weight loss reached 20.9%. The 10 mg dose is often considered the "golden dose" — offering substantial efficacy whilst many participants can tolerate side effects reasonably well.
Wegovy (semaglutide) reached its maximum 2.4 mg dose in STEP-1 trials, showing average weight loss of approximately 14.9% of body weight at 68 weeks under similar lifestyle conditions. Wegovy uses a single mechanism (GLP-1 only), whilst Mounjaro's dual GIP and GLP-1 action may explain the higher average weight loss percentage. However, clinical trial averages do not predict individual outcomes — some people on Wegovy achieve excellent results, and some on Mounjaro plateau at lower doses.
- Mounjaro 10 mg: ~19.5% average weight loss
- Wegovy 2.4 mg: ~14.9% average weight loss
- Both figures are averages from clinical trials
- Individual results vary considerably
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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 Is Right for You? Suitability and Next Steps
Both Mounjaro and Wegovy are prescription-only and require eligibility assessment by a UK-licensed prescriber or specialist. Eligibility generally includes: BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or obstructive sleep apnoea. Access is available through NHS specialist tier 3 weight management services (though waiting lists vary) or private online prescribing following a clinical consultation. Your prescriber will consider your medical history, other medications, and personal preference — there is no universally "better" choice. Some people respond better to one mechanism than the other. Use our free GLP-1 weight loss calculator to estimate potential weight loss at different doses, and our BMI calculator to check your starting point.
- 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 is the "golden dose" for Mounjaro and Wegovy?
The golden dose is the maintenance dose offering optimal weight loss with manageable side effects. For Mounjaro, this is typically 10 mg weekly (though some escalate to 15 mg). For Wegovy, it's the maximum 2.4 mg weekly. Both are reached through a gradual titration schedule over several weeks. Clinical trials showed Mounjaro 10 mg achieved ~19.5% average weight loss, whilst Wegovy 2.4 mg achieved ~14.9%.
Why does Mounjaro appear to achieve more weight loss than Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways. Wegovy is a GLP-1 agonist only, using a single mechanism. The dual mechanism may explain higher average weight loss in SURMOUNT trials compared to STEP trials. However, individual responses vary — some people achieve excellent results on either medication. Your prescriber can discuss which mechanism might suit you best.
Can I switch from Wegovy to Mounjaro or vice versa?
Yes, switching between medications is possible but must be managed by your prescriber. There is no official conversion chart — approximate equivalences exist (for example, Wegovy 2.4 mg is sometimes considered roughly equivalent to Mounjaro 10 mg), but any switch requires individual clinical assessment and supervision to ensure safety and appropriate dosing.
How do I access Mounjaro or Wegovy on the NHS in the UK?
Both medications are available through NHS specialist tier 3 weight management services via referral from your GP. NICE has approved tirzepatide (Mounjaro) for use within these services. Availability and waiting times vary significantly by region and local integrated care board (ICB). Your GP can advise on local access and waiting lists.
What if I don't qualify for NHS access — can I get these medications privately?
Yes. Both Mounjaro and Wegovy are available through GPhC-registered private online pharmacies following a clinical assessment with a UK-licensed prescriber. You do not need an NHS referral. Costs vary by provider and dose (approximately £129–£320 per month depending on dose and pharmacy). Ensure any private provider is GPhC-registered and prescribers are UK-licensed.
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