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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What is Monjiro? A Guide to Weight Management Options
"Monjiro" isn't a recognised medication name — you may be looking for information about Mounjaro (tirzepatide), a prescription-only weight management injection available in the UK. Mounjaro is a dual GIP and GLP-1 receptor agonist that may help support weight loss alongside a reduced-calorie diet and increased physical activity. This UK health guide explains what Mounjaro is, how it works, and whether it might be relevant for you. Always consult your GP or a licensed prescriber for personal advice about any weight management treatment.
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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.
Understanding Mounjaro — The Correct Name
If you've encountered the term "monjiro", it's likely a misspelling or mishearing of Mounjaro, which is the brand name for tirzepatide. Mounjaro is a prescription-only injectable medication licensed in the UK for weight management in adults. It works by activating two natural hormone pathways — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) — which may help regulate appetite, reduce food cravings, and support feeling fuller after meals.
In clinical trials (SURMOUNT-1), Mounjaro helped participants lose an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. It's important to note that Mounjaro is not insulin and works differently from diabetes medications. You can calculate your personal BMI using our free BMI calculator to understand whether you might be eligible for this type of treatment — typical eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions.
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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.
How to Access Mounjaro in the UK
Mounjaro is available in the UK through two main routes. On the NHS, access is through specialist tier 3 weight management services — your GP can refer you, though availability and waiting times vary significantly by region. In private healthcare, GPhC-registered online prescribers can issue prescriptions after a clinical assessment, and the medication is then dispensed by registered pharmacies.
Whatever route you choose, a prescriber will assess your individual health to determine suitability. Mounjaro comes as a once-weekly injection with doses ranging from 2.5 mg to 15 mg. Our GLP-1 weight loss calculator can help you understand potential outcomes at different doses. Always combine any medication with lifestyle changes — sustainable weight loss requires both reduced-calorie diet and increased physical activity.
- 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 "monjiro" the same as Mounjaro?
"Monjiro" is not an official medication name — it's likely a misspelling of Mounjaro (tirzepatide). Mounjaro is the correct brand name for a prescription-only weight management injection licensed in the UK. If you've seen "monjiro" online, check the spelling to ensure you're reading about the correct medication.
How does Mounjaro work differently from Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy contains only a GLP-1 agonist (semaglutide). Both may support weight loss, but Mounjaro's dual mechanism may produce different effects. Clinical trials show Mounjaro helped participants lose 15–21% body weight on average — individual results vary. Your prescriber can advise which is more suitable for you.
Who is eligible for Mounjaro on the NHS?
Typical NHS eligibility includes adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply. Access is through specialist weight management services — ask your GP about referral.
What are the main side effects of Mounjaro?
Common side effects include nausea, diarrhoea, constipation, and stomach pain — these often reduce over time. Serious side effects are rare but can include severe stomach pain (possible pancreatitis) or allergic reactions. Always inform your prescriber of any concerning symptoms. Full side effect details are in the patient information leaflet.
Can I use our weight converter to check my current weight before starting treatment?
Yes — use our free weight converter above to understand your weight in kg, stone, and pounds. Then use our BMI calculator to see where your weight falls on the NHS healthy weight ranges. This gives you a baseline before starting any weight management programme, whether medication or lifestyle-based.
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.