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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What Are the Requirements for Mounjaro in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK, but not everyone is eligible. Requirements depend on your BMI, health conditions, and whether you're accessing it through the NHS or privately. Understanding the eligibility criteria helps you determine if Mounjaro is right for you and what steps to take next with your GP or healthcare provider.
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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.
NHS Eligibility Criteria for Mounjaro
To qualify for Mounjaro through NHS specialist weight management services, you must meet specific BMI thresholds. Adults with a BMI of 30 or above (obesity) are typically eligible, or a BMI of 27–29.9 (overweight) if you also have at least one weight-related health condition. Weight-related conditions include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fat levels, obstructive sleep apnoea, or a history of heart attack or stroke.
For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — eligibility may start at BMI 27.5 or above — because these groups face higher health risks at lower weights. You can use our free BMI calculator above to check your personal BMI and see where you fall on the NHS scale.
Access to Mounjaro through the NHS is via tier 3 specialist weight management services, not standard GP prescriptions. Your GP can refer you, but waiting times vary significantly by region and can be lengthy in many areas.
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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.
NHS vs Private Access to Mounjaro in the UK
NHS access: NICE has approved tirzepatide for specialist weight management services, but availability depends on your local Integrated Care Board (ICB). NHS prescriptions follow strict protocols with specialist monitoring and dose titration guided by clinical teams. However, many regions have significant waiting lists.
Private access: Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Private access doesn't require NHS referral and is typically faster, though you pay directly. Costs vary by dose. Whichever route you choose, you'll still need a valid prescription and clinical assessment to ensure tirzepatide is safe and appropriate for your individual health situation.
- 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 for Mounjaro on the NHS?
You need a BMI of 30 or above, or 27–29.9 with a weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply (BMI 27.5+).
Can my GP prescribe Mounjaro directly?
Not typically. Mounjaro prescriptions come through NHS tier 3 specialist weight management services, not standard GP prescriptions. Your GP can refer you to these services, but you must be assessed by the specialist team first.
How long does it take to get Mounjaro on the NHS?
Waiting times vary widely by region. Some areas have waiting lists of several months to over a year. Private access through online prescribing is usually faster, though you'll pay privately. Check with your local ICB about current waiting times.
What health conditions count as weight-related for Mounjaro eligibility?
Weight-related conditions include type 2 diabetes, prediabetes, high blood pressure, dyslipidaemia (abnormal blood fats), obstructive sleep apnoea, and a history of heart attack, stroke, or cardiovascular disease.
Do I need any blood tests or medical checks for Mounjaro?
Yes. A prescriber will assess your medical history, current medications, and may request blood tests to check kidney and liver function before approving Mounjaro. This applies whether you're accessing it through NHS or private routes.
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.