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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Tirzepatide NICE Approval — What It Means for UK Patients
NICE (the National Institute for Health and Care Excellence) has approved tirzepatide (brand name Mounjaro) for weight management in UK adults through NHS specialist services. This approval means eligible patients can access tirzepatide as a prescription-only treatment following clinical assessment by a tier 3 or tier 4 weight management service. The approval is based on clinical trial evidence showing that tirzepatide, a GIP and GLP-1 receptor agonist, can help reduce body weight when used alongside lifestyle changes. However, NHS availability varies significantly by region, and access typically involves referral from your GP and assessment through specialist services.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Tirzepatide
NICE has set specific eligibility criteria for tirzepatide (Mounjaro) on the NHS. Adults may be eligible if they have:
- A BMI of 30 kg/m² or above (obese), or
- A BMI of 27 to 29.9 kg/m² with at least one weight-related health condition (such as type 2 diabetes, hypertension, or sleep apnoea), or
- A BMI of 27.5 or above if they are from South Asian, Chinese, Black African, or Black Caribbean backgrounds (due to higher health risks at lower BMI levels)
Tirzepatide is prescribed as a once-weekly injection using the KwikPen device. Clinical trials showed that tirzepatide helped participants lose an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. NICE recommends tirzepatide alongside a reduced-calorie diet and increased physical activity — the medication is not a substitute for lifestyle changes. Your GP can refer you to a specialist tier 3 weight management service to assess whether tirzepatide is appropriate for your individual health.
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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.
NHS vs Private Access — Getting Tirzepatide in the UK
NHS route: Available through specialist tier 3 or tier 4 weight management services following NICE approval. You must be referred by your GP, and assessments can involve waiting lists of several months in some regions due to high demand and variable regional funding.
Private route: Tirzepatide is also available through UK-licensed online prescribers without requiring an NHS referral. This route offers faster access but involves private costs. Both routes require a clinical assessment to confirm suitability. Use our free BMI calculator above to check your BMI and understand whether you may meet eligibility criteria, then discuss options with your GP or a licensed prescriber.
- 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.
Has NICE approved tirzepatide for NHS weight loss?
Yes. NICE has approved tirzepatide (Mounjaro) for weight management in UK adults meeting specific eligibility criteria. It is available through NHS specialist weight management services following referral from your GP, though regional availability and waiting times vary considerably.
What is the difference between NICE approval and MHRA approval?
The MHRA (Medicines and Healthcare products Regulatory Agency) approved tirzepatide as safe and effective for weight management. NICE then reviewed the evidence and approved it for NHS use based on clinical and cost-effectiveness. MHRA approval is required before NICE can recommend it, but NICE approval determines NHS availability.
What BMI do I need to be eligible for tirzepatide on the NHS?
Generally, a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea). Lower thresholds (BMI 27.5+) apply if you are from South Asian, Chinese, Black African, or Black Caribbean backgrounds.
How long does it take to access tirzepatide through the NHS?
Timescales vary by region. After GP referral to a specialist tier 3 weight management service, assessment and initial prescription can take weeks to months depending on local waiting lists and service capacity. Private routes typically offer faster access but at private cost.
Can I get tirzepatide without NHS referral?
Yes. Private UK-licensed prescribers and GPhC-registered pharmacies offer tirzepatide following an online clinical assessment, without requiring NHS referral. This offers faster access but is not covered by the NHS and involves private costs.
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.