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 Through the NHS in the UK
Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection now available through NHS specialist weight management services in the UK. As a dual GIP and GLP-1 receptor agonist, it works differently from other weekly weight loss injections, potentially helping to reduce appetite and support feeling fuller after meals. This guide explains NHS eligibility, NICE approval, how to access Mounjaro through specialist tier 3 services, and what clinical evidence shows about expected weight loss outcomes in UK healthcare.
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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 Approval for Mounjaro
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, making it available to eligible UK adults through tier 3 services. You may be eligible for NHS prescription if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² alongside a weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, obstructive sleep apnoea, or cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recognises lower BMI thresholds due to higher health risks at the same measurements — eligibility may begin at BMI 27.5 or above. Mounjaro comes as a KwikPen pre-filled injection device with doses starting at 2.5 mg and escalating to a maximum of 15 mg once weekly. Clinical trial data showed average weight loss of approximately 15–21% of body weight, though individual results vary significantly and depend on adherence to reduced-calorie diet and physical activity alongside medication.
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.
Accessing Mounjaro via NHS vs Private Route
NHS access requires referral from your GP to a tier 3 specialist weight management service — you cannot obtain Mounjaro directly from your GP practice. Waiting times and availability vary significantly by region and clinical commissioning group. Many areas have waiting lists extending several months or longer.
Alternatively, prescription weight loss treatment is available privately through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber, without requiring NHS referral. Our GLP-1 weight loss calculator can help you explore projected outcomes at different doses. Your GP remains your first point of contact for personalised advice about which route suits your circumstances and 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.
What is Mounjaro and how does it work for weight loss?
Mounjaro (tirzepatide) is a prescription-only weekly injection that activates two natural hormone pathways — GIP and GLP-1 — to help regulate appetite and support feeling fuller after meals. It slows gastric emptying and may help with food cravings, making it different from single-action GLP-1 injections like Wegovy.
Am I eligible for Mounjaro on the NHS in the UK?
You may qualify if you have a BMI of 30 or above, or 27–29.9 with a weight-related condition like type 2 diabetes or high blood pressure. South Asian, Chinese, Black African, or Black Caribbean adults may qualify at lower BMI thresholds. Eligibility is assessed individually by specialist services.
How much weight loss can I expect from Mounjaro?
Clinical trials showed average weight loss of approximately 15–21% of body weight over 72 weeks, alongside diet and exercise. Individual results vary significantly. Your GP or prescriber can discuss realistic expectations based on your personal circumstances.
How long does it take to get Mounjaro through the NHS?
Waiting times vary by region. Some areas have waiting lists of several months to over a year. Availability depends on your local clinical commissioning group. Your GP can advise on current wait times in your area when referring you to tier 3 services.
What are the common side effects of Mounjaro?
Most common side effects include nausea, diarrhoea, vomiting, constipation, and stomach pain — these often improve over time. Rare serious side effects include severe stomach pain (possible pancreatitis) and allergic reactions. Always discuss side effects with your prescriber.
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.