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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Should I Start Mounjaro? NHS and UK Eligibility Guide
Whether you should start Mounjaro depends on your eligibility through NHS specialist services or private prescribing, your health profile, and your commitment to lifestyle changes. In the UK, Mounjaro (tirzepatide) is a prescription-only weight management injection approved by the MHRA and recommended by NICE for eligible adults. This guide explains NHS eligibility criteria, how to access it, and what to consider before starting. Use our free BMI calculator above to check where you stand against NHS thresholds, and explore whether Mounjaro might be right for you based on UK health guidance.
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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 to Mounjaro in the UK
In the UK, Mounjaro is available through NHS specialist tier 3 weight management services for adults who meet strict eligibility criteria. You typically qualify if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, hypertension, or cardiovascular disease). South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower thresholds (BMI 27.5 or above) due to higher health risks at lower weights.
NICE has approved tirzepatide (Mounjaro) as a cost-effective option for NHS use, but access varies significantly by region. Accessing Mounjaro through the NHS typically requires referral from your GP to a specialist weight management service—waiting lists can extend months or years in many areas. Dose titration on the NHS follows the standard schedule: starting at 2.5 mg weekly, with increases to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg maximum, provided you tolerate each dose for at least 4 weeks.
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: Which Route Is Right for You?
If you want Mounjaro available sooner, private prescribing through GPhC-registered online services bypasses NHS waiting lists. You'll have a consultation with a UK-licensed prescriber, and if approved, receive your prescription dispensed by a registered pharmacy. Private costs typically range from £129–£320 monthly depending on dose.
The NHS route is free at point of use but involves waiting. The private route offers faster access but requires payment. Both routes require clinical assessment—your prescriber will review your weight, health conditions, medications, and weight loss goals. Starting Mounjaro, whether via NHS or private prescribing, is most effective alongside a reduced-calorie diet and increased physical activity. Try our GLP-1 weight loss calculator to estimate potential outcomes, and discuss your goals with your GP or prescriber to decide which route suits your situation best.
- 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 weight and BMI do I need to start Mounjaro on the NHS?
You typically need a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with a weight-related health condition like type 2 diabetes or hypertension. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at BMI 27.5 or above. Use our BMI calculator to check your current BMI against these thresholds.
How long does it take to access Mounjaro through the NHS?
NHS waiting times vary greatly by region. Some areas have waits of several months to over a year to access specialist tier 3 weight management services. Contact your local integrated care board (ICB) or ask your GP about typical waiting times in your area.
Can I get Mounjaro privately in the UK if I don't qualify for the NHS?
Yes. Private UK-licensed prescribers can assess your suitability independently of NHS criteria. Private access is faster but costs approximately £129–£320 monthly. You'll still need a clinical assessment to confirm the medication is safe and appropriate for you.
What's the difference between Mounjaro and Wegovy for NHS access?
Both are GLP-1-based weight loss injections licensed in the UK. Mounjaro is a dual GIP/GLP-1 agonist with a maximum dose of 15 mg weekly. Wegovy is a GLP-1 agonist with a maximum dose of 2.4 mg weekly. NICE guidance covers both; availability depends on your local specialist service. Clinical trials showed Mounjaro achieved slightly higher average weight loss (~21% vs ~15% body weight).
Will my GP prescribe Mounjaro directly, or do I need a referral?
In most cases, you'll need a referral from your GP to a specialist tier 3 weight management service. GPs typically cannot prescribe Mounjaro directly on the NHS. However, private prescribers can assess you directly without a referral. Always ask your GP about local options and waiting times first.
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.