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 for Diabetes — What You Need to Know
Mounjaro (tirzepatide) is a prescription-only injection licensed for both type 2 diabetes and weight management in the UK. It works differently from traditional diabetes medications by activating dual hormone pathways (GIP and GLP-1), which help regulate blood sugar and may support weight loss. This guide explains how Mounjaro works, how it compares to Wegovy, and what the clinical evidence shows. Always consult your GP or healthcare professional before considering any medication change.
10,000+ calculations today · NHS-aligned thresholds · 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/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.
Mounjaro vs Wegovy — Key Differences in Mechanism and Trial Data
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways simultaneously. This dual mechanism may explain why it shows higher average weight loss in clinical trials compared to single-action GLP-1 medications. In the SURMOUNT-1 trial, participants on the maximum dose (15 mg) lost an average of 20.9% of their body weight over 72 weeks, alongside diet and exercise changes.
Wegovy (semaglutide) is a GLP-1-only receptor agonist — it activates a single hormone pathway. In the STEP-1 clinical trial, participants on 2.4 mg lost an average of 14.9% of their body weight over 68 weeks. Both medications require reduced-calorie diet and increased physical activity for results. Individual outcomes vary significantly, and clinical trial averages do not represent assured personal results. Trial data shows both medications support meaningful weight loss when used as part of a comprehensive lifestyle approach, but the dual mechanism of Mounjaro demonstrated slightly higher average weight loss in its primary trial.
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.
Mounjaro for Type 2 Diabetes — NHS Context and Eligibility
Mounjaro is approved by the UK Medicines and Healthcare products Regulatory Agency (MHRA) for both type 2 diabetes management and weight management. For diabetes specifically, it may be prescribed when other medications have not provided adequate blood sugar control. Whether Mounjaro, Wegovy, or another medication is suitable depends on your individual health status, medical history, and treatment goals — only your prescriber can assess this.
Access in the UK varies: through NHS specialist services (with waiting lists varying by region) or private prescribing following an online clinical assessment. Our free GLP-1 weight loss calculator can help you understand potential outcomes at different doses, though actual results depend on your individual circumstances and adherence to lifestyle changes. Your GP can discuss the most appropriate option for your specific diabetes management needs.
- 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 Mounjaro used more for diabetes or weight loss?
Mounjaro is licensed for both. Originally developed for type 2 diabetes, it is now also approved for weight management in adults with obesity or overweight with comorbidities. Your prescriber will determine the primary use based on your individual health needs and goals.
Can I switch from Wegovy to Mounjaro on the NHS?
Any switch between medications must be managed by your prescriber. NHS access to both Mounjaro and Wegovy is through tier 3 specialist weight management services. Switching eligibility and availability depend on your region and the decision of your specialist team.
Does Mounjaro control blood sugar better than Wegovy?
Mounjaro's dual GIP and GLP-1 mechanism may offer different blood sugar control patterns compared to Wegovy's GLP-1-only action. Clinical evidence shows both are effective, but individual response varies. Your GP or diabetes specialist will assess which is most suitable for your specific needs.
What is the starting dose of Mounjaro for diabetes?
The starting dose is 2.5 mg once weekly, with gradual increases every 4 weeks. The dose is titrated based on your response and tolerability. Maximum dose is 15 mg once weekly. Your prescriber will manage the dose escalation process.
Do I need a UK prescription for Mounjaro?
Yes, Mounjaro is prescription-only in the UK. You cannot purchase it without a valid prescription from a UK-licensed prescriber. This requires a clinical assessment to confirm suitability for your individual health circumstances.
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.