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
Do I Qualify for Mounjaro on NHS?
Mounjaro (tirzepatide) is available through NHS specialist weight management services, but eligibility depends on your BMI, health conditions, and region. Both Mounjaro and Wegovy are now approved for NHS use in adults with obesity or overweight with related health conditions. Your GP can refer you to a specialist tier 3 or tier 4 weight management service for assessment, though access varies significantly across the UK. Understanding the eligibility criteria and how Mounjaro compares to Wegovy can help you discuss options with your healthcare team. Use our free BMI calculator to check where you stand instantly.
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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.
NHS Eligibility Criteria for Mounjaro vs Wegovy
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) follow the same NHS eligibility thresholds. You may qualify if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease history.
For adults of South Asian, Chinese, Black African, or Black Caribbean descent, lower thresholds apply: BMI 27.5 or above may qualify, as these groups face higher metabolic disease risk at lower weights. A KwikPen Mounjaro requires a prescription following clinical assessment by a specialist, not your GP alone. Wegovy uses a similar pathway. The SURMOUNT and STEP clinical trials showed different results: Mounjaro achieved up to 20.9% average weight loss at the maximum 15 mg dose, whilst Wegovy achieved approximately 14.9% at 2.4 mg—though individual outcomes 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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Prescription Route and Mechanism Differences
Both medications require a formal referral from your GP to a specialist weight management service and a clinical assessment before prescription. NHS access is through tier 3 or tier 4 specialist services, not standard GP prescription, and waiting lists can be lengthy in many regions. The key mechanism difference: Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways, whilst Wegovy is a single GLP-1 agonist. This may explain why tirzepatide showed higher average weight loss in SURMOUNT trials, but suitability depends on individual health, tolerability, and regional availability. Your specialist will assess which is more appropriate following your clinical assessment.
- 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 BMI do I need to qualify for Mounjaro on the NHS?
You need a BMI of 30 or above, or 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or heart disease. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, a BMI of 27.5 or above may qualify. Use our free BMI calculator above to check your current BMI instantly.
How does Mounjaro compare to Wegovy for NHS access?
Both follow identical NHS eligibility criteria and require specialist referral. Mounjaro is a dual GIP+GLP-1 agonist; Wegovy is GLP-1 only. SURMOUNT trials showed Mounjaro achieved higher average weight loss (up to 20.9%) than Wegovy's approximately 14.9%, but both are effective and individual results vary. Your specialist will recommend which suits your health profile.
How do I get referred to NHS Mounjaro treatment?
Ask your GP for a referral to your local tier 3 or tier 4 weight management service. They will assess your eligibility, medical history, and suitability for Mounjaro or an alternative. Waiting times vary by region; some areas have significant delays. Private assessment options are also available if NHS waiting times are lengthy.
Does tirzepatide (Mounjaro) work differently from semaglutide (Wegovy)?
Yes. Mounjaro activates both GIP and GLP-1 hormone pathways, whilst Wegovy activates GLP-1 only. The dual mechanism may explain higher weight loss results in SURMOUNT clinical trials, but both support appetite reduction and feeling fuller. Side effects are similar, though individual tolerability differs.
Will the NHS prescribe Mounjaro or Wegovy depending on availability?
Regional availability and NICE guidance influence which is offered. Some areas may prioritise one over the other based on local protocols and stock. Your specialist will discuss which is accessible and suitable for you. Private prescriptions are available if NHS waiting times are unacceptable or availability is limited in your region.
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.