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 5.0mg vs Wegovy — Key Differences Explained
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight management injections licensed in the UK, but they work differently and have distinct dose ranges. Mounjaro 5.0mg is an intermediate maintenance dose that activates two hormone pathways, whilst Wegovy uses a single mechanism. Understanding how these medications compare helps you and your prescriber decide which option might be most suitable for your individual circumstances. Both require clinical assessment before being prescribed.
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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 Work Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways simultaneously. The GIP pathway helps regulate fat storage and utilisation, whilst the GLP-1 pathway reduces appetite and helps you feel fuller after eating. This dual mechanism is why Mounjaro and Wegovy differ at a fundamental level.
Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates a single pathway to reduce appetite and slow gastric emptying. Clinical trials (STEP-1) showed Wegovy helped participants lose approximately 14.9% of their body weight over 68 weeks at the maximum 2.4mg dose. Mounjaro's SURMOUNT-1 trial showed approximately clinically studied weight loss at the maximum 15mg dose, though individual results vary significantly and these are not direct comparisons.
Use our GLP-1 weight loss calculator to explore potential weight loss trajectories at different doses of either medication.
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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.
Dose Ranges and Titration Schedules
Mounjaro 5.0mg is typically a mid-range maintenance dose after starting at 2.5mg and escalating weekly. Doses range from 2.5mg to 15mg maximum, with a minimum of 4 weeks at each dose level before increasing. Each KwikPen contains 4 weekly doses.
Wegovy begins at 0.25mg and escalates over 16+ weeks to a maximum of 2.4mg. The lower maximum dose reflects Wegovy's single-mechanism approach. Both medications are once-weekly injections, but the dose titration schedules differ significantly — Mounjaro uses larger dose increments, whilst Wegovy uses smaller, more gradual increases. Your prescriber will select the most appropriate medication and dosing schedule based on your individual health profile and response.
- 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 main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP + GLP-1 receptor agonist (activates two hormone pathways), whilst Wegovy is a GLP-1 only agonist (single pathway). This means Mounjaro works on appetite and fat regulation differently than Wegovy. Both are prescription-only and require clinical assessment.
Is Mounjaro 5.0mg a starting dose?
No. Mounjaro 5.0mg is typically an intermediate maintenance dose, usually reached after 4 weeks on the starting dose of 2.5mg. Doses are increased every 4 weeks from 2.5mg up to a maximum of 15mg, depending on individual response and prescriber guidance.
Which medication caused more weight loss in clinical trials?
Mounjaro's SURMOUNT-1 trial showed approximately 20.9% average weight loss at 15mg, whilst Wegovy's STEP-1 trial showed approximately 14.9% at 2.4mg. However, these are averages in controlled trials — individual results vary significantly, and direct comparisons are not straightforward. Your prescriber will advise on suitability for you.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between these medications must be managed by your prescriber. There is no official established conversion chart, though approximate equivalences exist based on clinical practice. Any change requires assessment and a new prescription.
How do I access Mounjaro or Wegovy in the UK?
Both medications are available through NHS specialist weight management services (tier 3) following GP referral, or through private online prescribing following an online clinical assessment with a UK-licensed prescriber. NHS access varies significantly by region and availability.
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.