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
How to Access Mounjaro in the UK
Mounjaro (tirzepatide) is available in the UK through both NHS specialist services and private online prescribing, but access routes differ significantly. The tirzepatide injection is prescription-only and requires a clinical assessment before dispensing. NHS availability depends on your local Integrated Care Board (ICB) and referral to specialist weight management services, which often have lengthy waiting lists. Private access is faster but costs vary by dose. Understanding your options helps you find the right route for your situation.
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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 vs Private Access Routes
NHS Route: Mounjaro is approved by NICE for use within NHS specialist weight management services (tier 3/4). You'll need a GP referral to your local specialist service, followed by clinical assessment. Availability and waiting times vary dramatically across the UK — some regions have waiting lists exceeding 12 months, whilst others have shorter timelines. Not all areas have equal access to tier 3 services.
- Referral from your GP to specialist weight management service
- Assessment by multidisciplinary team
- Prescription issued if clinically appropriate
- NHS funds the medication once approved
Private Route: Available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. No NHS referral needed. Faster access (typically within days), but you pay for the medication privately. Costs range from approximately £129–£320 per month depending on dose and provider.
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.
Mounjaro Eligibility and What Happens Next
You may be eligible for Mounjaro if you have a BMI of 30 or above, or BMI of 27–29.9 with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, dyslipidaemia, sleep apnoea, or cardiovascular disease). Lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. A prescriber will assess whether tirzepatide is suitable based on your individual health history, medications, and medical conditions. Use our free BMI calculator above to check where you stand against NHS eligibility thresholds. Your GP or licensed prescriber can then advise on the best access route for you.
- 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.
Can I get Mounjaro on the NHS right now?
Mounjaro is NICE-approved for NHS specialist weight management services, but availability varies significantly by region. Ask your GP about referral to your local tier 3 service. Waiting lists can be long in many areas. Private access is available without NHS referral if you want faster access.
How quickly can I get Mounjaro if I go private?
Private access is typically faster. After online clinical assessment with a prescriber, prescriptions are usually issued within days. The medication is then dispensed by a GPhC-registered pharmacy. Timescales depend on the provider, but expect access within 1–2 weeks.
What's the difference between NHS and private Mounjaro?
The medication is identical regardless of access route. The difference is speed, cost, and assessment process. NHS involves GP referral and specialist assessment (free but slower). Private involves online assessment (faster but you pay £129–£320/month depending on dose).
Do I need a prescription for Mounjaro?
Yes, Mounjaro is prescription-only. Both NHS and private routes require a prescription from a UK-licensed prescriber following clinical assessment. You cannot buy it without a prescription, and prescribers will assess your eligibility and medical suitability first.
What happens if I'm not eligible for Mounjaro?
If you don't meet eligibility criteria, your GP may suggest alternative weight management support, including NHS-funded lifestyle programmes, other prescription medications, or referral to specialist services. Individual assessment is essential — eligibility isn't always straightforward.
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.