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 7.5mg vs Wegovy — UK Comparison Guide
If you're exploring prescription weight loss injections in the UK, you may be comparing Mounjaro (tirzepatide) and Wegovy (semaglutide). At the 7.5mg Mounjaro dose, both medications have clinical evidence supporting weight loss, but they work differently. This guide explains how the two medications compare, what the clinical trials showed, and how your prescriber will help you decide which is right for you. Both are prescription-only and require clinical assessment before being prescribed in the UK.
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 and Wegovy lies in their mechanism. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways at once. This dual action may help regulate appetite, reduce cravings, and support feeling fuller after smaller meals. Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates a single hormone pathway.
In the SURMOUNT clinical trials, Mounjaro at 7.5mg showed average weight loss of approximately 19.5% of body weight over 72 weeks. In the STEP trials, Wegovy at 2.4mg (its equivalent maximum dose) showed average weight loss of approximately 14.9% of body weight. However, these are clinical trial averages — individual results vary significantly, and results depend on diet, activity level, and personal response to medication.
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.
Dose Comparison and What's Right for You
Mounjaro at 7.5mg is a mid-range escalation dose — most people start at 2.5mg and increase every 4 weeks. Wegovy titrates more slowly, starting at 0.25mg and reaching its maximum 2.4mg over approximately 16 weeks. Both medications require a prescription and clinical assessment. Your GP or a licensed prescriber will review your medical history, weight-related conditions, and eligibility. Access in the UK is through NHS specialist tier 3 weight management services (with regional waiting lists) or through private online prescribing with a GPhC-registered pharmacy. Your prescriber will advise which medication is more suitable based on your individual health profile — one is not universally "better" than the other.
- 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 7.5mg more effective than Wegovy?
Clinical trials showed different average outcomes, but these are not direct head-to-head comparisons. Mounjaro 7.5mg showed ~19.5% average weight loss in SURMOUNT trials; Wegovy 2.4mg showed ~14.9% in STEP trials. However, individual results vary widely based on genetics, lifestyle, and personal response. Your prescriber assesses which is suitable for you.
Can I switch from Wegovy to Mounjaro 7.5mg?
Yes, switching is possible, but must be managed by your prescriber. There is no official conversion chart — approximate equivalence suggests Mounjaro 7.5mg may be similar to Wegovy 1.7mg in effect. Any switch requires clinical guidance. Your prescriber will advise the safest approach for your situation.
How long does it take to reach Mounjaro 7.5mg?
Most patients start at 2.5mg, then increase by 2.5mg every 4 weeks. Reaching 7.5mg typically takes 12 weeks (3 dose escalations). Your prescriber may adjust this schedule based on side effects or tolerability.
Is Mounjaro 7.5mg available on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is NICE-approved and available through NHS specialist tier 3 weight management services. However, availability varies by region and waiting lists can be lengthy. Private access is available through online prescribing without NHS referral.
What are the main side effects at Mounjaro 7.5mg?
Common side effects include nausea, diarrhoea, vomiting, and constipation — most improve over time. Less common: indigestion, fatigue, headache, and injection site reactions. Seek urgent medical attention for severe stomach pain, allergic reactions, or vision changes.
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.