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 UK Results โ What the Evidence Shows
Mounjaro (tirzepatide) is a prescription-only weight loss injection licensed in the UK for adults with obesity or overweight-related health conditions. The SURMOUNT clinical trials showed that people using Mounjaro at the maximum 15 mg dose lost an average of around 21% of their body weight over 72 weeks โ though individual results vary significantly. Results in the UK are comparable to international trial data, and are achieved alongside a reduced-calorie diet and increased physical activity. This guide explains what UK adults can realistically expect from tirzepatide treatment, NHS eligibility, and how results compare to other weight loss medications.
10,000+ calculations today ยท NHS-aligned thresholds ยท 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/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ 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 โ 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 SURMOUNT Trial Results
UK eligibility for Mounjaro follows NICE guidance: adults with a BMI of 30 kg/mยฒ or above, or a BMI of 27โ29.9 kg/mยฒ with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds (from 27.5 kg/mยฒ) apply due to higher health risks at lower weights.
The SURMOUNT-1 clinical trial assessed tirzepatide outcomes:
- 5 mg dose: average clinically studied weight loss
- 10 mg dose: average clinically studied weight loss
- 15 mg dose: average clinically studied weight loss (over 72 weeks)
These results were achieved with a calorie-reduced diet and exercise programme. Weight loss typically begins within the first 4 weeks and continues as doses are escalated. Use our free GLP-1 weight loss calculator to estimate potential results at different Mounjaro doses tailored to your starting weight.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care โ 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 โ 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 โ completely free.
NHS Access vs Private Mounjaro in the UK
NHS access to Mounjaro is available through specialist tier 3 weight management services following GP referral, though availability and waiting times vary significantly by region. Some ICBs (integrated care boards) have approved tirzepatide; others do not yet offer it. Waiting lists can be several months to over a year in some areas.
Private prescribing of Mounjaro is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. Private Mounjaro costs vary by dose โ typically ยฃ200โยฃ320 per month โ and is not subsidised. Both routes require clinical assessment to confirm eligibility. Your GP can discuss which pathway is most suitable for you.
Check your personal BMI using our free BMI calculator to see whether you fall within NHS eligibility criteria, then discuss your options with your GP. If you choose private treatment, a prescriber will assess your medical history and suitability before issuing a prescription.
- 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 โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 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 | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/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 โ 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.
How much weight will I lose on Mounjaro in the UK?
Clinical trials showed an average loss of 15โ21% of body weight depending on dose โ approximately 10โ20 kg for many adults over 72 weeks. Individual results vary significantly based on starting weight, diet adherence, physical activity, and genetics. Your GP or prescriber can give personalised estimates.
How long does it take to see Mounjaro results?
Weight loss typically begins within the first 4 weeks of starting Mounjaro. Results accelerate as your dose increases (doses are escalated weekly or monthly up to 15 mg). Most significant loss occurs during weeks 4โ16 and continues beyond that.
Can I access Mounjaro through the NHS in the UK?
Yes, Mounjaro is available through NHS specialist weight management services (tier 3) if you meet eligibility criteria and are referred by your GP. However, availability varies by region and waiting lists can be lengthy. Private prescribing is also available without NHS referral.
Is Mounjaro better than Wegovy for weight loss results?
SURMOUNT trial data showed Mounjaro achieved slightly higher average weight loss (21% at 15 mg) than Wegovy trials (approximately 15% at 2.4 mg). However, individual variation is significant and results depend on adherence, diet, and exercise. Your prescriber will recommend the most suitable option for you.
What happens to weight loss results if I stop Mounjaro?
Weight regain is common after stopping tirzepatide โ studies show gradual weight return over months if diet and exercise are not maintained. Long-term results depend on sustained lifestyle changes. Your prescriber will discuss ongoing management plans with you.
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.