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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Wegovy Dose Compared to Mounjaro: UK Context
Both Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only weight loss injections available in the UK, but they work differently and use different dosing schedules. Understanding how their doses compare, and which NHS eligibility pathway applies to you, helps you have informed conversations with your GP or prescriber. This guide explains the dose differences, mechanisms, and how to access each medication through the NHS in the UK.
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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.
How Wegovy and Mounjaro Doses Compare
Wegovy (semaglutide) is a GLP-1 receptor agonist with a maximum weekly dose of 2.4 mg, escalated over five steps starting at 0.25 mg. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with a maximum weekly dose of 15 mg, starting at 2.5 mg and escalating over six steps. The key difference: Mounjaro's dual mechanism activates two hormone pathways, whilst Wegovy activates only the GLP-1 pathway.
- Wegovy escalation: 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg (4 weeks minimum per dose)
- Mounjaro escalation: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg (4 weeks minimum per dose)
- Approximate equivalence: Mounjaro 15 mg is broadly comparable to Wegovy 2.4 mg in terms of weight loss support, though individual responses vary
In NHS clinical trials, Wegovy achieved approximately 15% average body weight loss at maximum dose, whilst clinical data for Mounjaro shows 15–21% average weight loss depending on dose. Both require a reduced-calorie diet and increased physical activity for best results.
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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
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NHS Access and Eligibility in the UK
Both Wegovy and Mounjaro are available through NHS tier 3 specialist weight management services in England, though regional availability and waiting times vary significantly. NICE (the National Institute for Health and Care Excellence) has approved both medications for NHS use. Eligibility requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, cardiovascular disease, or hypertension. For adults of South Asian, Chinese, Black African, or Caribbean heritage, lower BMI thresholds may apply.
Access through the NHS typically involves a referral from your GP to your local integrated care board's tier 3 service. Waiting lists can be lengthy — in some areas several months or longer. Private prescribing routes are available without NHS referral through GPhC-registered online services, offering faster access but at personal cost. Your GP can advise which route is most appropriate for your circumstances.
To understand your personal weight management context, try our free BMI calculator above to see where your current weight sits on the NHS healthy weight scale. Our GLP-1 weight loss calculator can help you estimate potential results at different Wegovy or Mounjaro doses, based on clinical trial data. These tools provide helpful context for discussing medication eligibility with your GP or 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.
Which is more effective — Wegovy or Mounjaro?
Clinical trial data shows Mounjaro may produce slightly higher average weight loss (15–21% vs 15% for Wegovy), but individual results vary significantly. Both are effective. The "best" option depends on your health profile, eligibility, and what your prescriber recommends following assessment. There is no universally superior choice.
Can I switch from Wegovy to Mounjaro on the NHS?
Switching between medications is possible but requires prescriber guidance. There is no official NHS conversion protocol — any switch must be managed individually by your specialist service. If you have concerns about your current medication, discuss this with your tier 3 weight management service or GP.
How long does it take to reach maximum dose on each medication?
Wegovy reaches maximum dose (2.4 mg) in approximately 20 weeks (five 4-week steps). Mounjaro reaches maximum dose (15 mg) in approximately 24 weeks (six 4-week steps). You stay on your therapeutic dose thereafter; you do not continue to escalate.
Are Wegovy and Mounjaro available privately in the UK without NHS referral?
Yes. Both medications are available through private online prescribing services from UK-licensed prescribers, following an online clinical assessment. You do not need an NHS referral. Private prescribing costs vary by provider and dose, typically ranging £129–£320 per month.
What happens if I stop taking Wegovy or Mounjaro?
Weight regain is common after stopping either medication — clinical data shows most people regain weight gradually if they return to previous eating patterns. These are maintenance medications, not one-off treatments. Long-term use alongside sustained lifestyle changes gives the best results. Discuss duration and stopping plans with your prescriber.
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.