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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What Are The Mounjaro Doses And How Do They Compare To Wegovy?
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both prescription-only weight management injections available in the UK, but they have different dosing schedules and maximum doses. Mounjaro is a dual GIP and GLP-1 receptor agonist that starts at 2.5 mg and escalates to a maximum of 15 mg weekly, whilst Wegovy is a GLP-1-only medication that starts at 0.25 mg and reaches a maximum of 2.4 mg weekly. Understanding the differences between these dose ranges, titration schedules, and mechanisms can help you have an informed conversation with your prescriber about which option might be suitable for your individual health needs.
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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.
Mounjaro And Wegovy Dose Schedules — The Complete Breakdown
Mounjaro (tirzepatide) dosing follows a 4-week escalation schedule, starting lower but reaching a significantly higher maximum dose:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly
- Weeks 9–12: 7.5 mg once weekly
- Weeks 13–16: 10 mg once weekly
- Weeks 17–20: 12.5 mg once weekly
- Week 21+: 15 mg once weekly (maximum dose)
Wegovy (semaglutide) follows a 4-week escalation pattern with a lower overall maximum:
- Weeks 1–4: 0.25 mg once weekly (starting dose)
- Weeks 5–8: 0.5 mg once weekly
- Weeks 9–12: 1 mg once weekly
- Weeks 13–16: 1.7 mg once weekly
- Week 17+: 2.4 mg once weekly (maximum dose)
Both medications are once-weekly injections that you can self-administer at home. The key difference is that Mounjaro uses a dual mechanism (GIP + GLP-1 agonist), whilst Wegovy activates GLP-1 only. This may explain why clinical trials showed Mounjaro users achieved slightly higher average weight loss percentages (15–21% body weight) compared to Wegovy users (approximately 15% body weight), though individual results vary significantly.
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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.
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Clinical Trial Data And Individual Suitability — What Prescribers Consider
The SURMOUNT-1 clinical trial showed that Mounjaro at its maximum 15 mg dose resulted in an average weight loss of approximately 20.9% of body weight over 72 weeks when combined with lifestyle changes. The STEP-1 trial demonstrated Wegovy at 2.4 mg achieved approximately clinically studied weight loss over 68 weeks under similar conditions. However, these are trial averages — actual outcomes depend on your individual metabolism, adherence, diet, and activity level. Your prescriber will assess your medical history, current medications, and health conditions to determine which medication and dose escalation pathway is most appropriate for you. Neither medication is inherently "better" — suitability is individual and should be based on clinical assessment, not dose comparisons alone. Use our GLP-1 weight loss calculator to explore projected outcomes at different doses, and discuss your specific circumstances with your GP or a licensed prescriber.
- 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.
Can you skip doses or pause Mounjaro?
You should not skip doses without medical guidance. If you miss a Mounjaro dose within 4 days of your scheduled injection, take it as soon as you remember and continue your normal schedule. If more than 4 days have passed, skip that dose and take your next injection on your usual day. Speak to your prescriber before pausing treatment, as stopping suddenly may affect your weight management progress.
What if Mounjaro at 15 mg isn't working — can the dose go higher?
No. 15 mg once weekly is the maximum licensed dose of Mounjaro in the UK. If weight loss plateaus or slows, your prescriber may recommend continuing at 15 mg whilst reviewing your diet and activity level, or discussing alternative options. Some people maintain their current dose long-term; others may be offered different medication after clinical reassessment.
Is there an approximate dose equivalence between Mounjaro and Wegovy?
Approximate clinical equivalences suggest Mounjaro 5 mg ≈ Wegovy 0.5 mg, Mounjaro 10 mg ≈ Wegovy 1.7 mg, and Mounjaro 15 mg ≈ Wegovy 2.4 mg. However, there is no official conversion chart. Any switch between medications must be managed by your prescriber — they cannot simply be interchanged without medical oversight.
How do I know if I should start on Mounjaro or Wegovy?
Your prescriber will assess your BMI, weight-related health conditions, current medications, allergies, and medical history to recommend the most suitable option. Both require a prescription and clinical assessment. Eligibility for NHS prescribing varies by region; private prescribing is also available. Discuss your preferences and any health concerns with your prescriber, as they can explain which medication and dose schedule is most appropriate for you.
Are there any other weight loss injection options available in the UK?
Yes. Saxenda (liraglutide) is a GLP-1 injection licensed for weight management in the UK, but it is administered daily rather than weekly and has a maximum dose of 3 mg. Mounjaro and Wegovy are the two main once-weekly options currently available. Your prescriber can advise which is most suitable based on your individual circumstances and preferences.
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