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
Is Mounjaro a Diabetes Medication?
Mounjaro (tirzepatide) is not primarily a diabetes medication — it's licensed in the UK specifically for weight management in adults. However, because it's a GIP and GLP-1 receptor agonist, it does help regulate blood sugar, which is why it may benefit people with type 2 diabetes or prediabetes as a weight loss option. The confusion often arises because similar medications like Ozempic are used for diabetes, but Mounjaro's UK approval is for weight loss. Understanding the difference between Mounjaro and other GLP-1 treatments like Wegovy helps clarify what each medication is designed to do.
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: How Are They Different?
Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways in your body, which is what makes it unique. Wegovy is a single GLP-1 receptor agonist that works via one pathway. In the SURMOUNT clinical trials, Mounjaro (tirzepatide) showed average weight loss of approximately 15–21% of body weight at maximum dose (15 mg once weekly). In the STEP trials, Wegovy (semaglutide) showed average weight loss of around 15% at maximum dose (2.4 mg once weekly). Both are prescribed as once-weekly injections and require a UK prescription following clinical assessment. Neither is approved as a diabetes medication in the UK, though both may improve blood sugar control in people with prediabetes or type 2 diabetes as a secondary benefit when used for weight management.
- Mounjaro KwikPen: once-weekly, doses from 2.5 mg to 15 mg
- Wegovy: once-weekly, doses from 0.25 mg to 2.4 mg
- Both require NHS specialist referral or private prescription
- Individual results vary; clinical trial data is averaged across participants
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.
Which Medication Is Right for You?
Whether Mounjaro or Wegovy is suitable depends on your individual health profile, which is why a prescriber must assess you before either can be prescribed. Eligibility generally requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease. Your GP or a licensed prescriber will review your medical history, current medications, and health goals. Try our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and use our BMI calculator to check where you currently sit on the NHS scale. If you have type 2 diabetes and are considering weight loss treatment, your prescriber will coordinate with any diabetes medications you're already taking, as dose adjustments may be needed.
- 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 for type 2 diabetes in the UK?
Mounjaro (tirzepatide) is not licensed for diabetes treatment in the UK. It's approved specifically for weight management. However, weight loss itself often improves blood sugar control, and the medication does help regulate glucose as a secondary benefit. People with type 2 diabetes may be eligible if they meet BMI thresholds, but it's prescribed for weight loss, not as a primary diabetes treatment.
What's the difference between Mounjaro and Ozempic?
Both contain similar medications in the GLP-1/GIP family, but Ozempic (semaglutide) is licensed for type 2 diabetes management in the UK at doses up to 2 mg. Mounjaro is licensed for weight management specifically. Ozempic is not approved for weight loss in the UK, though it may have a weight loss effect as a secondary benefit.
Can I get Mounjaro or Wegovy on the NHS?
Both are available through NHS tier 3 specialist weight management services via GP referral, though availability and waiting times vary significantly by region. Private access is available through online consultations with UK-licensed prescribers, followed by dispensing via a GPhC-registered pharmacy. NHS waiting lists can be lengthy in many areas.
Does Mounjaro work better than Wegovy for weight loss?
Clinical trial data shows Mounjaro had slightly higher average weight loss (15–21%) than Wegovy (15%) in their respective trials, but these are averaged results. Individual outcomes vary significantly. Only a prescriber can assess which is more suitable for your specific health profile and needs.
Do I need a prescription for Mounjaro or Wegovy?
Yes, both are prescription-only medicines in the UK. You cannot buy them over the counter. You'll need a clinical assessment by a GP or licensed prescriber before either can be prescribed. This assessment checks your BMI, health conditions, medications, and suitability for treatment.
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.