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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NHS Criteria for Mounjaro: Who Is Eligible?
If you're considering Mounjaro (tirzepatide) for weight management in the UK, understanding the NHS criteria is essential. The NHS has specific eligibility thresholds based on BMI and health conditions. Not everyone will meet these criteria through NHS specialist services, but your GP can assess your individual circumstances and refer you to tier 3 weight management services if appropriate. This guide explains exactly who qualifies under current NICE 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 BMI Thresholds for Mounjaro Eligibility
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services with these criteria:
- BMI of 30 kg/m² or above (obesity category), OR
- BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, NHS guidance recommends lower thresholds due to increased health risks at lower BMI levels — eligibility may start at BMI 27.5 or above. Use our free BMI calculator above to check your personal BMI instantly and see where you fall against these thresholds. Your GP can then discuss whether referral to a specialist weight management service is appropriate for your situation.
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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.
Weight-Related Health Conditions That May Qualify
Having a BMI between 27–29.9 kg/m² alone is not enough — you must have at least one clinically significant weight-related health condition. These include:
- Type 2 diabetes or prediabetes
- High blood pressure (hypertension)
- Abnormal blood fats (dyslipidaemia)
- Obstructive sleep apnoea
- Previous heart attack, stroke, or cardiovascular disease
- Osteoarthritis or mobility problems related to weight
Your GP will assess whether your health conditions qualify you for specialist referral and Mounjaro treatment through the NHS pathway.
- 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's the difference between NHS and private access to Mounjaro?
NHS access is through tier 3 specialist weight management services — typically requiring a GP referral and specialist assessment. Private access is available through UK-licensed prescribers following an online clinical assessment, without NHS referral. NHS availability varies significantly by region (ICB), and waiting lists can be lengthy. Private access is usually faster but involves out-of-pocket costs.
Can I get Mounjaro through my GP directly on the NHS?
Not typically. Most GPs do not prescribe Mounjaro directly. Instead, your GP refers you to a tier 3 or tier 4 specialist multidisciplinary weight management service. The specialist team then assesses your eligibility against NICE criteria and decides whether Mounjaro is appropriate. This is why understanding the NHS criteria beforehand helps.
Does Mounjaro vs Wegovy make a difference to NHS eligibility?
No — both tirzepatide (Mounjaro) and semaglutide (Wegovy) are subject to the same NHS BMI and health condition criteria. Mounjaro is a dual GIP and GLP-1 agonist (different mechanism), while Wegovy is a GLP-1 agonist only. Clinical trial data shows both can support weight loss, though individual results vary. Your specialist will determine which is most suitable.
What happens during a specialist weight management assessment for Mounjaro?
The specialist team will review your medical history, current medications, BMI, health conditions, previous weight loss attempts, and lifestyle factors. They'll discuss whether medication (including Mounjaro with its dose titration schedule) is appropriate alongside dietary and activity changes. If approved, your Mounjaro KwikPen prescription begins at 2.5 mg weekly, escalating to a maintenance dose over weeks.
Is there a minimum wait time before NHS referral for Mounjaro?
There's no national minimum, but many NHS services require evidence of previous structured weight loss attempts (diet, exercise, behaviour change programmes). Some regions implement 6–12 month waiting periods before Mounjaro consideration. Waiting lists for specialist services vary significantly across the UK. Your GP can advise on timelines in your area.
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.