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
Free tracker included with every download this week
What Is Mounjado? A UK Health Guide
Mounjado is not currently a recognised or licensed medication name in the UK health system. You may be thinking of Mounjaro (tirzepatide), which is the prescription-only weight management injection licensed by the MHRA in the UK. Alternatively, you might be searching for information about Wegovy (semaglutide), another licensed weight loss injection. Both are GLP-1 receptor agonist medications available through NHS specialist services or private prescribing following a clinical assessment. This guide clarifies the difference and helps you understand UK-approved weight management options and healthy weight 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.
UK-Licensed Weight Management Injections
In the UK, two main prescription-only weight management injections are currently licensed and available:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist manufactured by Eli Lilly. It's administered once weekly and comes in doses from 2.5 mg up to 15 mg. Clinical trials showed participants lost an average of 15–21% of their body weight alongside dietary changes and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 receptor agonist made by Novo Nordisk. Also given once weekly, with a maximum dose of 2.4 mg. STEP trial data showed average weight loss of approximately 15% body weight.
Both medications work by activating hormone pathways in the gut that help regulate appetite and support feeling fuller after smaller meals. Individual results vary significantly, and both require a clinical assessment by a UK-licensed prescriber before being issued.
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.
How to Access Weight Management Treatment in the UK
Access to prescription weight loss treatment follows two main routes. NHS access is through specialist tier 3 or tier 4 weight management services — you'll need a GP referral, though waiting lists vary by region and can be lengthy. Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber; no NHS referral is needed.
Your GP or prescriber will assess your eligibility based on your BMI and any weight-related health conditions. Use our free BMI calculator above to check your personal BMI, and our GLP-1 weight loss calculator to estimate potential outcomes at different doses. Both tools help you prepare for a consultation and understand what treatment might mean for your health.
- 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 Mounjado a real medication?
Mounjado is not a recognised licensed medication in the UK. You may be searching for Mounjaro (tirzepatide) or Wegovy (semaglutide), both of which are prescription-only weight management injections approved by the MHRA. Always check the exact spelling of any medication and confirm with your GP or pharmacist before seeking it.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist (up to 15 mg weekly); Wegovy is a GLP-1 agonist only (up to 2.4 mg weekly). Both are once-weekly injections licensed for weight management in the UK. Mounjaro showed slightly higher average weight loss in clinical trials, but individual results vary. Your prescriber will advise which suits your situation.
Can I get these injections on the NHS?
Yes, but access is limited. You'll need referral to a specialist NHS weight management service (tier 3 or 4), typically through your GP. Availability and waiting times vary significantly by region. Private access via online prescribing is also available without an NHS referral.
What health conditions qualify me for prescription weight loss treatment?
You may qualify if you have a BMI of 30 or above, or 27–29.9 with a weight-related condition such as type 2 diabetes, high blood pressure, high cholesterol, sleep apnoea, or cardiovascular disease. Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Your prescriber will assess your individual situation.
Are these injections safe?
Both Mounjaro and Wegovy are licensed medications approved by the MHRA, meaning they've undergone rigorous safety testing. However, they do have side effects — commonly nausea, diarrhoea, and constipation — and aren't suitable for everyone. Pregnancy, certain medical conditions, and some medications mean you shouldn't take them. Always discuss with your prescriber before starting.
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.