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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Eli Lilly Mounjaro: NHS Access and UK Eligibility
Mounjaro (tirzepatide), manufactured by Eli Lilly, is a prescription-only GLP-1 and GIP receptor agonist available through NHS specialist weight management services in the UK. NICE (National Institute for Health and Care Excellence) has approved tirzepatide for use within the NHS tier 3 weight management pathway. This guide explains how to access Mounjaro through the NHS, who qualifies, and what the clinical evidence shows about its effectiveness in helping UK adults manage excess weight.
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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 recommends Mounjaro for adults with a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with weight-related health conditions including type 2 diabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds due to higher metabolic health risks at these weights. The Mounjaro KwikPen contains four doses (four weeks' supply), with titration starting at 2.5 mg and escalating to a maximum of 15 mg per week under GP or specialist supervision.
- Access through NHS tier 3 specialist weight management services, not standard GP prescription
- Requires referral from your GP to your local integrated care board (ICB) weight management service
- Clinical trials (SURMOUNT-1) showed average weight loss of 15–21% body weight depending on dose
- Results achieved alongside reduced-calorie diet and increased physical activity
- Individual outcomes vary significantly between patients
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: Timelines and Availability
NHS access to Mounjaro is available through specialist weight management services, though availability and waiting times vary significantly across UK regions. Some areas have established pathways; others have long waiting lists due to demand exceeding capacity. Private prescribing routes are also available in the UK through GPhC-registered online services following a clinical assessment by a UK-licensed prescriber. Check your local ICB website or ask your GP about tier 3 weight management services in your area. Use our GLP-1 weight loss calculator to understand potential outcomes, and the BMI calculator above to assess your current eligibility criteria.
- 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 do I access Mounjaro through the NHS in the UK?
Ask your GP to refer you to your local NHS tier 3 weight management service. These are specialist multidisciplinary services that assess suitability and can prescribe Mounjaro. Your GP cannot prescribe it directly — it requires specialist assessment. Waiting times vary by region from weeks to months.
What is the difference between Mounjaro and Ozempic?
Both are made by Eli Lilly, but Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist licensed for weight management, whilst Ozempic (semaglutide) is primarily a diabetes medication. Mounjaro is the weight-specific product. Ozempic use for weight loss is off-label in the UK.
What does NICE say about Mounjaro for weight management?
NICE has appraised tirzepatide positively and recommends it as part of NHS tier 3 weight management services for eligible adults. It recognises the SURMOUNT trial evidence and recommends use alongside lifestyle changes, not as a standalone treatment.
How much weight can I lose with Mounjaro from Eli Lilly?
Clinical trials showed average weight loss of 15–21% body weight over 72 weeks at maximum doses, alongside a reduced-calorie diet and exercise. Individual results vary significantly. Your GP or specialist can discuss realistic expectations based on your personal circumstances.
What is the Mounjaro KwikPen and how does it work?
The KwikPen is Eli Lilly's pre-filled injection device for Mounjaro. Each pen contains four doses (four weeks' supply). You inject once weekly into your stomach, thigh, or upper arm. The dose increases gradually every 4 weeks based on your response and tolerability.
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.