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 Advice for UK Adults — NHS and Private Routes
If you're considering Mounjaro (tirzepatide) for weight management in the UK, understanding NHS eligibility, NICE guidance, and your prescribing options is essential. Mounjaro is a prescription-only, once-weekly injectable medication licensed in the UK for adults with obesity or overweight with weight-related health conditions. This guide covers NHS access through specialist services, private prescribing pathways, and what you need to know before approaching your GP or a prescriber.
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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 Guidance for Mounjaro
NICE (National Institute for Health and Care Excellence) has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services. This means the medication can be prescribed through tier 3 and tier 4 NHS weight management programmes, though access varies significantly by region and local integrated care board (ICB) decisions.
You may be eligible for NHS Mounjaro if you have:
- A BMI of 30 kg/m² or above (obesity), OR
- A BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition such as type 2 diabetes, prediabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS applies lower BMI thresholds (from 27.5 kg/m²) due to higher metabolic risk in these populations. Important note: You cannot access Mounjaro directly from your GP. You must be referred to a specialist tier 3 weight management service, and waiting times can be lengthy in many areas. Use our free BMI calculator above to check whether you meet the initial BMI threshold for assessment.
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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 — Routes to Mounjaro in the UK
NHS route: Referral by your GP to a specialist weight management service (tier 3), clinical assessment, then prescription if approved. This can take weeks to months due to waiting lists. There is no cost once prescribed, but availability varies widely by ICB area.
Private route: Online consultation with a UK-licensed prescriber following a clinical assessment, prescription issued if appropriate, dispensed by a GPhC-registered pharmacy. Available without NHS referral, typically costs £129–£320 per month depending on dose and provider. Faster access, but you pay out of pocket. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different Mounjaro doses alongside lifestyle changes, and our weight converter allows you to track progress in your preferred units (kg, stone, or lbs).
- 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 my GP prescribe Mounjaro directly?
No. Mounjaro is only prescribed through NHS specialist tier 3 or tier 4 weight management services, not by GPs. You'll need a GP referral to access these services. Your GP can discuss your eligibility and refer you, but the prescription decision is made by the specialist team.
What does "tirzepatide" mean, and is it the same as Mounjaro?
Tirzepatide is the active ingredient in Mounjaro. "Mounjaro" is the brand name. The terms are used interchangeably in the UK. Your prescription may show either name depending on whether it's branded or generic tirzepatide (once generics become available).
How does Mounjaro compare to Wegovy in NHS terms?
Both are GLP-1 based weight loss medications approved by NICE. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist. Wegovy (semaglutide) is a GLP-1 agonist only. Both require specialist prescription. Clinical trial data shows Mounjaro produces slightly higher average weight loss (~20.9% body weight at maximum dose vs ~15% for Wegovy), though individual results vary significantly.
What happens if I don't meet NHS eligibility criteria?
If you don't meet NHS BMI thresholds or have no eligible comorbidities, you may still access Mounjaro privately through an online prescriber following a clinical assessment. You would pay privately and wouldn't go through the NHS specialist pathway. A UK-licensed prescriber will assess your individual suitability.
How long does the NHS referral and assessment process take?
This varies significantly by region. Some areas have waits of 3–6 months; others up to 1–2 years. Contact your local ICB for typical waiting times in your area. If you need faster access, private prescribing may be a quicker alternative, though at personal cost.
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.