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
Who Makes Mounjaro and How It Compares to Wegovy
Mounjaro is manufactured by Eli Lilly and Company, a major global pharmaceutical manufacturer. It's a prescription-only weight management injection containing tirzepatide, approved in the UK for adults with obesity or overweight with weight-related health conditions. Wegovy, by contrast, is made by Novo Nordisk and contains semaglutide. Both are once-weekly injections licensed for UK weight management, but they work differently and come from different manufacturers. Understanding the difference between these two medications can help you and your GP make an informed decision about which might suit you.
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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.
Mounjaro vs Wegovy: Manufacturer, Mechanism, and Trial Data
Eli Lilly manufactures Mounjaro (tirzepatide), whilst Novo Nordisk manufactures Wegovy (semaglutide). The key difference lies in how they work. Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways simultaneously. Wegovy is a GLP-1 receptor agonist only, activating a single pathway. In clinical trials, this dual mechanism gave Mounjaro slightly different results: the SURMOUNT-1 trial showed participants lost an average of 20.9% body weight on the maximum 15 mg dose over 72 weeks. Wegovy's STEP-1 trial showed average weight loss of approximately 14.9% over 68 weeks on the maximum 2.4 mg dose. Both studies combined medication with reduced-calorie diet and increased physical activity — individual results vary significantly, and these are trial averages, not assured outcomes. Our GLP-1 weight loss calculator can help you explore projected results at different doses.
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.
Eligibility, Prescription Access, and Which Might Suit You
Both Mounjaro and Wegovy require a UK prescription and clinical assessment before being prescribed. Eligibility is similar for both: adults with a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds. Access is available through NHS specialist tier 3 weight management services (with potential waiting lists) or private online prescribers. Your GP or prescriber will assess which medication — if either — is appropriate based on your individual health profile, medical history, and preferences. Neither Mounjaro nor Wegovy is "better" — suitability depends on your personal circumstances.
- 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.
Who manufactures Mounjaro in the UK?
Mounjaro (tirzepatide) is manufactured by Eli Lilly and Company, a major global pharmaceutical manufacturer. It's imported and distributed in the UK as a prescription-only medicine. The injection comes in a pre-filled KwikPen device delivered in doses from 2.5 mg to 15 mg.
What's the difference between Mounjaro and Wegovy manufacturers?
Mounjaro is made by Eli Lilly; Wegovy is made by Novo Nordisk. They contain different active ingredients (tirzepatide vs semaglutide) and work through different mechanisms — Mounjaro activates dual GIP and GLP-1 pathways, whilst Wegovy activates GLP-1 only.
How do I get Mounjaro in the UK?
You'll need a prescription from a UK-licensed healthcare provider. Access is available through NHS specialist weight management services (referral from your GP) or private online prescribers following a clinical assessment. You cannot buy Mounjaro over the counter.
Is Mounjaro better than Wegovy for weight loss?
Clinical trials show slightly different average outcomes — Mounjaro showed approximately 20.9% average weight loss; Wegovy showed approximately 14.9%. However, individual results vary considerably, and the "better" option depends on your personal health profile. Your prescriber will assess which is more suitable for you.
Can I use our BMI calculator to check if I'm eligible for Mounjaro?
Yes — our free BMI calculator will show your personal BMI instantly. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions, you may be eligible. However, only a registered prescriber can assess full eligibility after a clinical consultation.
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.