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 in the UK: NHS and Private Access
Mounjaro (tirzepatide) is a prescription-only weekly injection licensed in the UK for weight management in adults. Access is available through both NHS specialist weight management services and private online prescribing following a clinical assessment. This guide covers NHS eligibility criteria, how the two-tier access system works, what NICE recommends, and what you can expect at different stages of treatment in the UK.
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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 Tier 3 Weight Management Services
In the UK, Mounjaro for weight loss is typically accessed through NHS tier 3 specialist weight management services, though availability varies significantly by region. NICE (National Institute for Health and Care Excellence) has approved tirzepatide (Mounjaro) as a cost-effective option for eligible adults.
You may be eligible for NHS Mounjaro if you have:
- BMI of 30 kg/m² or above, OR
- BMI of 27–29.9 kg/m² with a weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease)
- Lower thresholds apply for South Asian, Chinese, Black African, or Black Caribbean adults (BMI 27.5+)
Access requires a referral from your GP to your local integrated care board's tier 3 service. Check your BMI now using our free BMI calculator to understand where you stand. Waiting times for NHS tier 3 services can range from weeks to several months, depending on your region.
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.
Private vs NHS: Access Routes and Cost in the UK
NHS route: Free at point of use but requires GP referral and specialist assessment. Regional availability is inconsistent, and waiting lists can be lengthy. Once approved, ongoing monitoring is provided by NHS staff.
Private route: Available immediately through GPhC-registered online pharmacies. Requires an online clinical assessment with a UK-licensed prescriber. Costs typically range from £120–£180 per month depending on dose. You manage your own injections and monitor progress independently, though many private providers offer support.
Try our GLP-1 weight loss calculator to explore projected weight loss outcomes at different doses, then discuss which route suits your situation with your GP or a private prescriber.
- 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.
How long does Mounjaro take to show weight loss results in the UK?
Weight loss typically begins within the first 2–4 weeks, but the most significant results appear after 8–12 weeks of consistent use. The SURMOUNT-1 trial showed average weight loss of 15–21% over 72 weeks at maximum dose, though individual results vary considerably. Your prescriber will review progress at regular intervals.
What is the NHS NICE guidance on Mounjaro for weight management?
NICE recommends tirzepatide as a cost-effective treatment for eligible adults with BMI ≥30 or BMI 27–29.9 with comorbidities. It is recommended for use within specialist tier 3 services alongside lifestyle changes. NICE emphasises that weight loss medications are not replacements for diet and physical activity.
Can I get a weekly weight loss injection through the NHS in the UK?
Yes, Mounjaro is a once-weekly injection available through NHS tier 3 specialist weight management services for eligible adults. Access requires GP referral and specialist assessment. Private access is also available immediately through GPhC-registered pharmacies without NHS referral. Use our progress tracker to monitor outcomes whichever route you choose.
What is the difference between Mounjaro and Wegovy for UK weight loss?
Both are once-weekly injections licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may provide slightly greater average weight loss, but individual responses vary. Your prescriber will assess which is suitable for you.
Do I need my GP's permission to access private Mounjaro in the UK?
No. Private access through online prescribing does not require GP referral or permission, though it is good practice to inform your GP. A private UK-licensed prescriber will conduct a clinical assessment to confirm suitability. Private prescribers operate within the same regulatory framework as NHS prescribers regarding eligibility and safety checks.
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.