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
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Which Mounjaro Dose Is Most Effective for Weight Loss?
The most effective Mounjaro dose varies between individuals — there's no single "best" dose that works for everyone. Clinical trials show that higher doses tend to produce greater average weight loss, with the maximum 15 mg dose delivering the strongest results. However, effectiveness also depends on your starting weight, metabolism, other health conditions, and how your body responds during the dose titration schedule. Your prescriber will assess what's right for you individually. Using our GLP-1 weight loss calculator can help you explore potential outcomes at different doses based on your circumstances.
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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.
Clinical Trial Data: Mounjaro vs Wegovy Dose Effectiveness
Mounjaro (tirzepatide) demonstrated dose-dependent weight loss in the SURMOUNT-1 clinical trial across 72 weeks. At the 5 mg maintenance dose, participants lost an average of 15% of their body weight. At 10 mg, average loss increased to approximately 19.5%, and at the maximum 15 mg dose, the average reached 20.9%. This is a dual GIP and GLP-1 receptor agonist mechanism — activating two hormone pathways rather than one.
Wegovy (semaglutide) is a GLP-1-only agonist. In the STEP-1 trial, the maximum 2.4 mg dose produced an average weight loss of approximately 14.9% over 68 weeks. The two medications work through different mechanisms: Mounjaro's dual action may explain slightly higher average weight loss figures in trials, though individual responses vary significantly. A prescriber will assess which mechanism suits your physiology and medical history better.
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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.
Finding Your Effective Dose: Titration and Individual Response
Both Mounjaro and Wegovy use gradual dose escalation — you don't start at the highest dose. Mounjaro begins at 2.5 mg weekly, increasing every 4 weeks if tolerated, up to 15 mg maximum. This dose titration schedule allows your body to adapt and helps your prescriber identify the lowest effective dose for you personally. Some people achieve excellent results at 5 mg or 7.5 mg and don't need higher doses. Others benefit from maximum-dose treatment. Effectiveness isn't just about the number on the pen — it's about consistent use, adherence to reduced-calorie diet and physical activity, and how your individual metabolism responds. Your GP or prescriber will monitor your progress and adjust accordingly.
- 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 15 mg Mounjaro always more effective than lower doses?
Not necessarily for every person. While clinical trials show 15 mg produced the highest average weight loss (20.9%), many individuals achieve excellent results at lower doses like 5 mg or 10 mg. Effectiveness depends on your starting weight, metabolism, and personal response. Some people plateau before reaching maximum dose. Your prescriber will assess your individual progress and adjust based on results, not just reach for the highest dose.
How does Mounjaro's dose effectiveness compare to Wegovy?
In clinical trials, Mounjaro showed slightly higher average weight loss across most doses due to its dual GIP+GLP-1 mechanism, versus Wegovy's GLP-1-only action. However, individual results vary considerably — some people respond better to Wegovy, others to Mounjaro. The difference in mechanism may make one more suitable for your health profile. Your prescriber will recommend based on your medical history, not just comparative trial averages.
How long does it take to find my effective Mounjaro dose?
The standard titration takes 16–20 weeks to reach a stable maintenance dose (increasing every 4 weeks). However, finding your individually effective dose may take longer — your prescriber monitors your weight loss progress, side effects, and health markers to determine whether you need to continue escalating or stay at your current dose for best results.
Can I stay on a lower Mounjaro dose if it's working well?
Yes. If you're achieving consistent weight loss and good health outcomes at 5 mg, 7.5 mg, or 10 mg, there's no medical requirement to increase further. The goal is effective weight management with manageable side effects — not reaching the maximum dose. Your prescriber will support whatever dose produces the best balance for you.
What's the difference between tirzepatide and Mounjaro?
Tirzepatide is the active ingredient; Mounjaro is the brand name. Tirzepatide is the generic name for the dual GIP+GLP-1 receptor agonist. When you receive a Mounjaro prescription, you're receiving tirzepatide formulated in the Mounjaro KwikPen. Understanding both names helps you navigate prescriptions and NHS or private pathways clearly.
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.