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
Free tracker included with every download this week
Mounjaro's Highest Dosage vs Wegovy: How They Compare
Mounjaro's highest dosage is 15mg per week, while Wegovy's maximum is 2.4mg per week—but these are not directly comparable due to different mechanisms. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whereas Wegovy (semaglutide) acts on GLP-1 only. Both are prescription-only injections licensed in the UK for weight management. Clinical trial data shows different weight loss outcomes, but individual results vary significantly. Your prescriber will assess which medication, if any, suits your health profile. Try our free GLP-1 weight loss calculator to explore potential outcomes, and use our BMI calculator to understand your starting point.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Mounjaro vs Wegovy: Clinical Trial Data and Dosing Differences
Mounjaro dosing: Starts at 2.5mg once weekly, escalates by 2.5mg increments every 4 weeks, up to a maximum of 15mg per week. In the SURMOUNT-1 clinical trial, participants on Mounjaro 15mg lost an average of approximately 20.9% of their body weight over 72 weeks, alongside reduced-calorie diet and increased physical activity.
Wegovy dosing: Starts at 0.25mg weekly, escalates to a maximum of 2.4mg per week over approximately 16 weeks. The STEP-1 trial showed participants on Wegovy 2.4mg lost approximately 14.9% of body weight over 68 weeks with the same lifestyle support.
- Mounjaro's dual mechanism (GIP + GLP-1) may explain higher average weight loss in trials
- Wegovy is a single-mechanism GLP-1 agonist with a longer UK prescription history
- Individual responses vary—some people respond better to one mechanism than the other
- Both require clinical assessment; neither is suitable for everyone
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Them: Clinical Assessment and Individual Suitability
Neither Mounjaro nor Wegovy is "better"—the choice depends on your individual health profile, medical history, and how your body responds. A UK-licensed prescriber will assess your eligibility, medications, and any contraindications before recommending one. Both medications require a UK prescription and are subject to individual clinical assessment. Mounjaro carries additional MHRA monitoring (Black Triangle ▼ status) due to newer market presence. Access is through NHS specialist weight management services or private online prescribing with a licensed healthcare professional. Your GP can refer you to NHS tier 3 services, though waiting lists vary significantly by region.
- 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's the highest dose of Mounjaro I can take?
The maximum dose of Mounjaro is 15mg once per week. You start at 2.5mg and increase by 2.5mg every 4 weeks, only if tolerated. Not everyone needs or reaches the highest dose—your prescriber will decide the right dose for you based on side effects and response.
Is Mounjaro 15mg more effective than Wegovy 2.4mg?
Clinical trials showed Mounjaro 15mg produced higher average weight loss (20.9%) than Wegovy 2.4mg (14.9%), but these are trial averages. Individual results vary significantly. The dual mechanism of Mounjaro may explain the difference, but response is personal. Your prescriber will help you choose based on your circumstances.
Can I switch from Wegovy to Mounjaro at the highest dose?
No. If switching medications, you would start Mounjaro at its lowest dose (2.5mg) and titrate up over weeks, regardless of your previous Wegovy dose. Switching requires prescriber supervision and is not a direct escalation—it's a new medication cycle.
Which is available on the NHS in the UK?
Both Mounjaro and Wegovy are NICE-approved and available through NHS specialist weight management (tier 3) services, but availability and waiting times vary by region. Private access is available through GPhC-registered online pharmacies with a UK prescription.
What if the highest dose doesn't work for me?
If you're on the maximum dose and not seeing results, your prescriber may discuss stopping treatment, trying a different medication, or exploring other options like bariatric surgery referral. Weight loss medications work best alongside lifestyle changes—diet and activity matter as much as the injection. ```
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.