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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Mpunjaro in the United Kingdom — What You Need to Know
Mpunjaro is the brand name for tirzepatide, a prescription-only weight management injection licensed in the UK for adults with obesity or overweight with weight-related health conditions. This UK health guide explains how Mpunjaro works, who may be eligible, how to access it through the NHS or privately, and what the evidence shows about weight loss outcomes. MyWeightCheck provides free healthy weight UK information tools, including our BMI calculator and weight converter, to help you understand your health context alongside medical guidance from your GP.
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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.
How Mpunjaro Works and What It Does
Mpunjaro is a dual GIP and GLP-1 receptor agonist — this means it activates two natural hormone pathways that regulate appetite and blood sugar. Unlike single-mechanism medications, Mpunjaro's dual action may help reduce food cravings, support feeling fuller after smaller meals, and slow how quickly food leaves your stomach.
The medication works by mimicking hormones your body naturally produces after eating. This supports nhs guidance on weight management through appetite regulation alongside a reduced-calorie diet and increased physical activity. Mpunjaro is injected once weekly using a pre-filled KwikPen device — injection sites rotate between stomach, thigh, and upper arm.
- Activates GIP and GLP-1 hormone pathways
- May reduce appetite and food cravings
- Slows stomach emptying (initially)
- Once-weekly injection
- Pre-filled KwikPen device
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.
Mpunjaro Eligibility and NHS Access in the UK
In the UK, you may be eligible for Mpunjaro if you have a BMI of 30 kg/m² or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease. Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage — eligibility may begin at BMI 27.5 or above.
NHS access is through tier 3 specialist weight management services following a GP referral. Availability varies significantly by region and waiting lists can be lengthy. Private prescribing is also available following an online clinical assessment with a UK-licensed prescriber. Always discuss your individual situation with your GP or a qualified healthcare professional to understand what options suit you.
- 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.
Is Mpunjaro available on the NHS in the UK?
Yes. NICE has approved tirzepatide (Mpunjaro) for NHS use within specialist tier 3 weight management services. Access requires a GP referral and eligibility assessment. Availability and waiting times vary by region. Private prescribing is also available following online clinical assessment.
What weight loss can I expect from Mpunjaro?
Clinical trials showed Mpunjaro users lost an average of 15–21% of body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly. Weight loss is not guaranteed — your GP can discuss realistic expectations for your situation.
What are the main side effects of Mpunjaro?
Very common side effects include nausea, diarrhoea, constipation, vomiting, and stomach pain — usually mild and improving over time. Less common effects include injection site reactions, fatigue, and hair loss. Seek immediate medical attention for severe stomach pain, gallbladder symptoms, or serious allergic reactions.
How do I use Mpunjaro — is it difficult to inject?
Mpunjaro is a once-weekly pre-filled KwikPen injection that most users find straightforward. Your prescriber will provide injection training. You inject into your stomach, thigh, or upper arm — rotate sites weekly. Pens are stored in a refrigerator unopened, then at room temperature for up to 30 days after first use.
Can I get Mpunjaro privately without waiting for the NHS?
Yes. Private prescribing is available through UK-licensed prescribers via online consultations. Following clinical assessment, prescriptions are dispensed by GPhC-registered pharmacies. Costs vary by dose but typically range from £129–£320 monthly. You do not need NHS referral for private access.
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.