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
How Mounjaro Works for Weight Loss on the NHS
Mounjaro (tirzepatide) is available on the NHS for weight management in adults who meet specific eligibility criteria. This prescription-only injection is a once-weekly GLP-1 and GIP receptor agonist that may help reduce appetite and support weight loss alongside diet and physical activity. Access through the NHS varies by region, and eligibility is assessed by specialist weight management services. Understanding how the NHS provides this treatment can help you explore whether it's right for your situation.
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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 Access Routes
NHS eligibility for Mounjaro typically includes:
- BMI of 30 kg/m² or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, prediabetes, hypertension, or cardiovascular disease
- Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults (BMI 27.5 or above) due to higher health risks at lower weights
- Access through tier 3 specialist weight management services — not standard GP prescription
- Your GP can refer you to your local specialist service, but availability and waiting times vary significantly across NHS regions
NICE (National Institute for Health and Care Excellence) has approved tirzepatide for use within NHS weight management services. However, regional differences mean some areas may have longer waiting lists or different eligibility criteria. Use our free GLP-1 weight loss calculator to help understand potential outcomes alongside your GP assessment.
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 for Mounjaro
NHS access: Referral to tier 3 specialist service, free prescription once approved, but significant waiting times in many areas (sometimes several months to over a year). Regional variation means your local ICB (Integrated Care Board) determines availability.
Private access: Available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. No NHS waiting list required, faster access to treatment, but costs apply (typically £150–£280 per month depending on dose). Both routes require a formal clinical assessment before prescription. Track your progress once started using our free weight loss progress tracker.
- 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 I get Mounjaro on the NHS if I have a BMI of 28?
If your BMI is 28 and you have a weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease), you may be eligible. If you are of South Asian, Chinese, Black African, or Black Caribbean heritage, the threshold is lower. Your GP can assess your eligibility and make a referral to specialist services.
What is the typical waiting time for Mounjaro on the NHS?
Waiting times vary significantly by region. Some areas have waiting lists of several months to over a year, whilst others may be shorter. Contact your local NHS weight management service for specific timelines, or ask your GP about private options if waiting times are a concern.
How much does Mounjaro cost privately in the UK?
Private Mounjaro treatment typically costs £150–£280 per month depending on the dose and provider. This is approximately four weeks' supply (one KwikPen with four injections). Prices vary between providers, so it's worth comparing options. Use our BMI calculator to understand your starting point.
What happens if I don't meet NHS eligibility criteria but want to try Mounjaro?
If you don't qualify through the NHS, you can access Mounjaro privately through a GPhC-registered online pharmacy following a clinical assessment. You'll need a valid UK prescription from a licensed prescriber, but you won't need an NHS referral. This route is faster but involves private costs.
Is there an NHS approved weight loss injection alternative to Mounjaro?
Yes. Wegovy (semaglutide 2.4 mg) and Saxenda (liraglutide) are also NHS-approved GLP-1 medications for weight loss. Mounjaro is unique as a dual GIP/GLP-1 agonist. Your specialist service will assess which is most appropriate for you based on clinical factors, though NHS availability of these medications also varies by region.
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.