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 Doctors Prescribe Mounjaro in the UK?
Yes, doctors can prescribe Mounjaro in the UK — but not all GPs can, and the route depends on whether you access it through the NHS or privately. Mounjaro (tirzepatide) is approved by the MHRA and recommended by NICE for weight management in eligible UK adults. However, NHS prescribing is typically restricted to specialist tier 3 weight management services rather than standard GP practices. Understanding how the prescribing system works will help you know what to expect and which route suits your situation best.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Prescribing and Eligibility Criteria
NICE guidance approves Mounjaro for NHS use, but access depends on your local NHS commissioning. Mounjaro is typically prescribed through tier 3 specialist weight management services, not routine GP appointments. You'll usually need a GP referral to these services first.
You may be eligible if you have:
- A BMI of 30 kg/m² or above, or
- A BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, cardiovascular disease)
- For South Asian, Chinese, Black African, or Black Caribbean adults: lower thresholds may apply (BMI 27.5+)
NHS availability varies significantly by region and ICB commissioning. Waiting lists for tier 3 services can extend from months to years in many areas. Your GP can discuss local options and check your eligibility.
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 Prescribing Routes
NHS route: Free at point of use once prescribed through specialist services, but limited availability and long waiting lists.
Private route: Available through GPhC-registered online prescribing services following a clinical assessment — faster access but requires payment (typically £129–£320+ per month depending on dose). Use our GLP-1 weight loss calculator to estimate potential weight loss at different Mounjaro doses, regardless of which prescribing route you choose. A licensed prescriber will assess whether tirzepatide is clinically appropriate for your individual health profile.
- 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 my GP prescribe Mounjaro directly from their surgery?
Most GPs cannot prescribe Mounjaro routinely. NHS prescribing is managed through tier 3 specialist weight management services. Your GP can refer you to these services, but the prescription comes from the specialist team, not your GP practice directly.
What does NICE say about Mounjaro prescribing?
NICE has approved tirzepatide (Mounjaro) for weight management in eligible UK adults. NICE recommends it for use within specialist weight management services for those meeting BMI and health criteria. NICE guidance supports NHS prescribing where commissioning allows.
How long is the NHS waiting list for Mounjaro?
Waiting times vary significantly by region. Some areas have waits of several months to over a year. Contact your local tier 3 weight management service or ask your GP about current waiting times in your area, as availability and demand differ across NHS regions.
Can I get Mounjaro prescribed privately without NHS waiting lists?
Yes. Private prescribing through online clinical assessments is available without NHS waiting lists. A UK-licensed prescriber will assess your eligibility following an online consultation. Private prescriptions typically cost £129–£320+ per month depending on dose and provider.
What happens after I'm prescribed Mounjaro — do I need ongoing GP support?
Yes. Your GP should monitor your progress and manage any interactions with other medications. NHS specialist services provide ongoing clinical support. If using private prescribing, you should still inform your GP and maintain regular check-ups for overall health monitoring.
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.