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
Buying Mounjaro Privately vs Wegovy — Which Is Right for You?
If you're considering buying Mounjaro privately in the UK, you may also be wondering how it compares to Wegovy, the other leading prescription weight management injection. Both are licensed in the UK and available privately through online clinical assessments, but they work differently and suit different people. This guide compares the two based on clinical evidence, mechanism, dosing, and suitability, so you can understand what to expect before consulting a prescriber.
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.
How Mounjaro and Wegovy Work Differently
The key difference between Mounjaro (tirzepatide) and Wegovy (semaglutide) is their mechanism of action. Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two separate hormone pathways in your body. GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) both signal appetite suppression and fullness. By targeting both pathways, Mounjaro may offer a more comprehensive effect on appetite and weight regulation.
Wegovy is a GLP-1 receptor agonist only, activating just the GLP-1 pathway. This single-mechanism approach has been used successfully for years and has robust clinical trial data supporting its effectiveness.
In clinical trials, Mounjaro (SURMOUNT-1) showed average weight loss of approximately 15–21% of body weight depending on dose. Wegovy (STEP-1) showed average weight loss of approximately 15% at the maximum dose. Individual results vary significantly — these are averages achieved alongside reduced-calorie diet and increased physical activity, not medication alone.
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.
Doses, Cost, and Private Access in the UK
Mounjaro starts at 2.5 mg and escalates to a maximum of 15 mg once weekly. Wegovy starts at 0.25 mg and escalates to 2.4 mg once weekly. Both are once-weekly injections available privately through UK-licensed prescribers following an online clinical assessment. Private costs typically range from £129–£320 per month depending on dose and provider. When buying privately, you'll need a valid UK prescription issued by a licensed healthcare professional. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses. Your prescriber will assess your BMI, medical history, and suitability before issuing a prescription — both medications are only available with 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 → 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.
Can I buy Mounjaro privately without NHS referral in the UK?
Yes. Mounjaro is available privately through UK-licensed prescribers via online clinical assessment. You do not need an NHS referral. However, you must have a valid prescription from a UK-licensed healthcare professional — both Mounjaro and Wegovy are prescription-only medicines. The prescriber will assess your eligibility based on your BMI and health profile.
Which weight loss faster — Mounjaro or Wegovy?
Clinical trials showed Mounjaro achieved slightly higher average weight loss (15–21% vs 15% for Wegovy), but individual results vary significantly. The best medication is the one your prescriber determines is most suitable for your specific health profile and circumstances. Both require consistent diet and exercise changes alongside medication.
Are Mounjaro and Wegovy the same price privately?
Prices vary by provider and dose. Both typically cost £129–£320 per month privately. Mounjaro's maximum dose (15 mg) may be at the higher end, while Wegovy's maximum dose (2.4 mg) is usually slightly lower. Always check current prices with your prescriber.
What if Mounjaro doesn't work for me — can I switch to Wegovy?
Yes, a prescriber can switch you between medications if needed. Any medication change should be managed by your healthcare professional. Approximate dose equivalences exist (e.g. Mounjaro 10 mg ≈ Wegovy 1.7 mg), but your prescriber will guide the transition based on your response and tolerance.
Do I need an NHS appointment before buying Mounjaro privately?
No. Private tirzepatide (Mounjaro) access does not require an NHS referral or GP involvement. You can access an online clinical assessment directly with a private UK-licensed prescriber. However, you may wish to inform your GP for your medical records. NHS access is available through specialist tier 3 weight management services if you prefer NHS 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.