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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Golden Dose Mounjaro vs Wegovy: What's the Difference?
The term "golden dose" refers to the optimal Mounjaro dose where weight loss results stabilise—typically 10mg or 15mg weekly. If you're comparing Mounjaro (tirzepatide) with Wegovy (semaglutide), it's important to understand their different mechanisms and how they work. Both are prescription-only GLP-1-based weight loss injections available in the UK following clinical assessment, but they're not identical. This guide explains the key differences to help you understand what your prescriber might recommend.
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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: Mechanism and Dosing Differences
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—meaning it activates two natural hormone pathways simultaneously. This dual action may explain why it showed slightly higher average weight loss in clinical trials. The SURMOUNT-1 trial showed average weight loss of approximately 20.9% at the maximum 15mg dose over 72 weeks.
Wegovy (semaglutide) is a GLP-1-only agonist, activating a single pathway. The STEP-1 trial showed average weight loss of approximately 14.9% at the maximum 2.4mg dose over 68 weeks. Both medications work by reducing appetite, supporting satiety, and slowing gastric emptying—but Mounjaro's dual mechanism may provide additional metabolic support.
- Mounjaro dosing: 2.5mg starting dose, escalating weekly to maximum 15mg over approximately 20 weeks
- Wegovy dosing: 0.25mg starting dose, escalating weekly to maximum 2.4mg over approximately 16 weeks
- Both: Once-weekly KwikPen injections; both require prescription and clinical assessment; both used alongside reduced-calorie diet and increased physical activity
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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.
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Which Is Right for You? Individual Suitability and Prescriber Assessment
Both Mounjaro and Wegovy are licensed for UK adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, cardiovascular disease, or sleep apnoea). Your prescriber will assess which is more suitable based on your individual health profile, medical history, and any contraindications.
The "golden dose" concept applies mainly to Mounjaro—where stabilisation occurs around 10–15mg—but Wegovy reaches its maximum at 2.4mg. Neither medication assures specific weight loss; individual results vary significantly. Your GP or specialist prescriber will guide your starting dose and titration schedule. Track your progress with our free progress tracker to monitor changes alongside your clinical reviews.
- 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.
What does "golden dose" mean for Mounjaro?
The golden dose refers to the Mounjaro dose at which weight loss results typically stabilise for most users—usually 10mg or 15mg weekly. Doses before this point (2.5mg–7.5mg) are part of the escalation phase. The term is informal and results vary individually; your prescriber will determine your optimal dose based on tolerability and response.
Is Mounjaro better than Wegovy for weight loss?
Clinical trials suggest Mounjaro may produce slightly higher average weight loss (20.9% vs 14.9%), but this doesn't mean it's "better" for every individual. Suitability depends on your health profile, tolerability, side effects, and prescriber assessment. Both are effective prescription-only medications requiring clinical evaluation. Your prescriber will recommend the most appropriate option for you.
How long does it take to reach the golden dose on Mounjaro?
Mounjaro requires a minimum of 4 weeks on each dose before escalation. Starting at 2.5mg, it typically takes approximately 20 weeks (5 months) to reach the 15mg maximum dose. Some users may stabilise at 10mg. Your prescriber may adjust the schedule based on your tolerability and response to each dose increase.
Can I switch between Mounjaro and Wegovy?
Switching between tirzepatide and semaglutide is possible but must be managed by your prescriber. There is no official established conversion chart—approximate equivalences exist (10mg Mounjaro ≈ 1.7mg Wegovy; 15mg Mounjaro ≈ 2.4mg Wegovy), but any switch requires clinical guidance. Never stop one and restart another without prescriber supervision.
How do I access Mounjaro or Wegovy in the UK?
Both medications are prescription-only and available through NHS specialist tier 3 weight management services (with referral from your GP, though waiting lists vary significantly by region) or through private online prescribing following a clinical assessment. Use our GLP-1 weight loss calculator to estimate potential results at different doses, and discuss eligibility with your GP or a licensed prescriber.
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