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
Mounjaro Studies and UK Access — What You Need to Know
Mounjaro (tirzepatide) is supported by robust clinical research, including the SURMOUNT trials, which demonstrated its effectiveness for weight management. If you're considering this prescription-only injection, it's important to understand both the evidence behind it and how to access it in the UK. This guide covers the key studies, cost context, and practical steps for accessing Mounjaro through NHS specialist services or private prescription routes. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses based on clinical trial data.
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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.
Clinical Evidence and UK Cost Context
Mounjaro's approval is based on the SURMOUNT-1 clinical trial, which showed that adults on the maximum 15 mg dose lost an average of approximately 20.9% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. The dual GIP and GLP-1 mechanism sets tirzepatide apart from single-agent GLP-1 agonists like semaglutide (Wegovy). In the UK, private prescription costs vary by dose and provider, typically ranging from £130 to £320 per month. NHS access is limited to specialist tier 3 weight management services following referral from your GP, though availability depends significantly on your local ICB (Integrated Care Board). Individual results vary, and pricing reflects the monthly cost of treatment before any clinical consultations or delivery charges.
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.
NHS vs Private Access — How to Get Started
NHS route: Request a referral to your local specialist weight management service from your GP. Mounjaro has been approved by NICE for NHS use, but access depends on local commissioning and waiting lists can be substantial. Private route: Complete an online consultation with a UK-licensed prescriber through a GPhC-registered pharmacy. The consultation assesses your BMI, medical history, and medications to determine suitability. If approved, your prescription is dispensed and delivered. Both routes require clinical assessment — Mounjaro is not available without a prescription. Calculate your personal BMI using our free BMI calculator to check initial eligibility criteria before consulting a prescriber.
- 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.
What are the main SURMOUNT trial results for Mounjaro?
The SURMOUNT-1 trial showed that adults taking 15 mg Mounjaro lost an average of 20.9% of their body weight over 72 weeks, compared to 3.3% on placebo. Results at lower doses (5 mg and 10 mg) averaged around 15% and 19.5% respectively. All results were achieved alongside dietary changes and increased physical activity.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £130 to £320 per month depending on dose and provider. Prices reflect the medication only — additional consultation or delivery charges may apply. Always confirm the full cost before starting treatment, as pricing varies between different online prescribing services.
Can I access Mounjaro through the NHS?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use within specialist weight management services. However, NHS access requires a GP referral to your local tier 3 service and depends on local commissioning. Waiting lists vary significantly by region — some areas have delays of several months or longer.
What's the difference between Mounjaro (tirzepatide) and Wegovy (semaglutide)?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy activates GLP-1 only. SURMOUNT trials showed Mounjaro achieved slightly higher average weight loss (up to 20.9%) compared to Wegovy's approximately 14.9%. Both are prescription-only and both have similar side effect profiles. Individual results vary regardless of medication choice.
What's involved in a private Mounjaro consultation?
An online consultation with a UK-licensed prescriber reviews your medical history, current medications, BMI, and weight-related health conditions. The prescriber assesses whether tirzepatide is suitable for you. If approved, a prescription is issued to a GPhC-registered pharmacy for dispensing. The entire process typically takes 1–3 working days.
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.