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 Maintenance Dose vs Wegovy: UK Comparison
The maintenance dose of Mounjaro is 15mg once weekly, compared to Wegovy's maximum 2.4mg once weekly — but which medication is right for you depends on individual factors, not dose strength alone. Both are prescription-only GLP-1 (or dual GIP/GLP-1) injections licensed in the UK for weight management, and both reach their maintenance dose through a gradual titration schedule. Understanding how these medications compare — including their mechanisms, clinical trial data, and how your GP or prescriber decides between them — is essential for informed decisions about your weight management journey.
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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 Mounjaro and Wegovy Dosing Schedules Compare
Mounjaro (tirzepatide) reaches its 15mg maintenance dose over 20 weeks, starting at 2.5mg and increasing every 4 weeks. Wegovy (semaglutide) reaches 2.4mg over 16 weeks, beginning at 0.25mg and escalating weekly. The key difference isn't just dose size — it's mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways, while Wegovy is a single GLP-1 agonist.
Clinical trial data shows Mounjaro achieved average weight loss of approximately 20.9% body weight at the 15mg maintenance dose (SURMOUNT-1 trial), whilst Wegovy achieved approximately 14.9% at 2.4mg (STEP-1 trial). However, individual results vary significantly, and these trials included reduced-calorie diet and increased physical activity alongside medication. Both injections are administered once weekly via pre-filled pens — Mounjaro uses the KwikPen, Wegovy uses an auto-injection pen. Your prescriber will assess which dosing schedule and mechanism suits your individual health profile, medical history, and response to initial doses.
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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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Which Maintenance Dose Is Right for You?
Neither medication's maintenance dose is inherently "better" — suitability depends on your personal circumstances, not dose strength alone. Some people respond well to Wegovy's single mechanism and lower dose, whilst others benefit more from Mounjaro's dual-action approach. Your GP or licensed prescriber will consider your weight, BMI, existing health conditions (such as type 2 diabetes or cardiovascular disease), other medications you take, and how you tolerate initial doses before deciding between them.
Both medications require a clinical assessment before prescription in the UK. Use our free GLP-1 weight loss calculator to explore projected weight loss at different doses and understand what realistic outcomes look like for your starting weight. You can also track your progress using our progress tracker once you begin treatment, helping you and your prescriber assess response over time.
Access in the UK is available through NHS specialist tier 3 weight management services (with variable waiting times by region) or through private online prescribing services following a digital clinical assessment. Whichever route and medication you choose, success depends on combining the injection with sustained dietary changes and increased physical activity — medication alone is not sufficient for long-term weight management.
- 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's 15mg dose stronger than Wegovy's 2.4mg?
The doses are not directly comparable — they're different medications with different potencies. Mounjaro's higher numerical dose reflects its dual GIP/GLP-1 mechanism. Clinical trials showed Mounjaro achieved slightly higher average weight loss, but individual results vary. Your prescriber decides based on your health profile, not dose numbers alone.
How long does it take to reach Mounjaro's maintenance dose?
Mounjaro reaches 15mg over approximately 20 weeks, starting at 2.5mg and increasing every 4 weeks (2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg). Wegovy takes 16 weeks to reach 2.4mg. Slower titration allows your body to adjust and helps your prescriber monitor side effects.
Can you switch from Wegovy to Mounjaro or vice versa?
Switching between GLP-1 medications is possible but must be managed by your prescriber. There's no official conversion chart — approximate equivalences exist (e.g., Wegovy 2.4mg ≈ Mounjaro 10–15mg), but any switch requires a new clinical assessment and prescription.
Is Mounjaro available on the NHS in the UK?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use within specialist tier 3 weight management services. Availability varies significantly by region and ICB (Integrated Care Board). You'll need a GP referral to NHS specialist services. Waiting lists can be several months to years depending on your area.
What happens if I don't respond well to the maintenance dose?
If you're not losing weight as expected at maintenance dose, your prescriber may investigate whether you're combining medication with adequate dietary changes and physical activity, check for medication interactions, or consider whether a different medication might suit you better. Continuing indefinitely at a dose that's not working isn't recommended.
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.