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 Weight Loss Drugs — What You Need to Know in the UK
Mounjaro (tirzepatide) is a prescription-only weight loss injection now licensed in the UK for adults with obesity or overweight with weight-related health conditions. It works differently from other weight loss drugs by activating two natural hormone pathways — GIP and GLP-1 — to help reduce appetite and support sustainable weight loss. In clinical trials, Mounjaro helped people lose an average of 15–21% of their body weight when used alongside a reduced-calorie diet and increased physical activity. Access in the UK is available through NHS specialist weight management services or private online prescribing. Understanding how Mounjaro works, who can access it, and what to expect is essential before considering this medication as part of your weight loss journey.
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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 and NICE Guidance for Mounjaro
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, making it available to eligible adults across England, Scotland, Wales, and Northern Ireland. To qualify for NHS Mounjaro, you must have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² alongside at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, or sleep apnoea.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recognises lower BMI thresholds due to higher metabolic risk at these weights. NHS access is provided through tier 3 or tier 4 specialist weight management services — not standard GP prescription. Your GP can refer you to your local specialist service, though waiting times vary significantly by region. A specialist team will assess your individual health, confirm eligibility, and discuss whether Mounjaro is appropriate for you before prescribing. Use our free BMI calculator above to check where you fall on the NHS eligibility scale.
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.
NHS vs. Private Access to Mounjaro in the UK
NHS access to Mounjaro involves referral to a specialist tier 3 service, assessment, and prescription through the NHS — this is free at the point of use but waiting lists in many areas are substantial, sometimes 6–12 months or longer. Private access is available through UK-licensed online prescribers without waiting for NHS referral; you complete an online clinical assessment and pay for the medication privately, typically between £129–£320 per month depending on your dose.
Both routes require a clinical assessment to confirm safety and suitability. The choice between NHS and private depends on your circumstances, budget, and willingness to wait. Our free weight loss calculator can help you explore potential outcomes at different Mounjaro doses, and our progress tracker will help you log your weight management journey once treatment begins. Whichever route you choose, Mounjaro is always combined with lifestyle changes — diet and exercise remain essential.
- 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 makes Mounjaro different from other weight loss injections like Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways rather than one. Wegovy (semaglutide) activates GLP-1 only. Clinical trials suggest Mounjaro may produce slightly greater average weight loss — around 20.9% body weight at the maximum dose compared to approximately 15% with Wegovy — but individual results vary significantly. Both require prescription and clinical assessment.
Am I eligible for Mounjaro on the NHS?
You may be eligible if you have 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. South Asian, Chinese, Black African, or Black Caribbean adults may qualify at lower BMI thresholds. Your GP can refer you to a specialist weight management service for assessment. Contact your local NHS ICB for details about waiting times in your area.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs between £129–£320 per month depending on your dose and the provider. Starting doses (2.5–5 mg) are usually lower cost; maximum dose (15 mg) costs more. Prices vary between online prescribers, so it's worth comparing. Always use a GPhC-registered pharmacy to ensure medication safety and legitimacy.
What happens if I'm on the NHS waiting list for Mounjaro?
Waiting times vary by region — some areas have waiting lists of 6–12 months or longer due to high demand. While waiting, your GP or practice nurse can discuss weight management support, lifestyle changes, and other tier 2 options. Some people choose private access to start sooner while remaining on the NHS waiting list. Ask your specialist service about their current waiting time when referred.
Is Mounjaro covered by my private health insurance?
Coverage varies widely between insurance providers and policies. Some premium policies may cover weight management medications following specialist assessment, while others exclude them or require pre-authorisation. Contact your insurer directly with your policy number to ask about tirzepatide (Mounjaro) coverage before pursuing private prescription.
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.