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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How To Use The Golden Dose Mounjaro
The "golden dose" of Mounjaro refers to the maximum 15mg weekly injection — the highest strength available in the UK. This is the dose many people aim for after gradually stepping up from 2.5mg over approximately 20 weeks. Understanding how to reach and use the golden dose safely is important if you're considering tirzepatide for weight management. Here's what you need to know about the dosing schedule, administration, and what to expect as you progress.
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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.
Understanding The Mounjaro Dose Titration Schedule
Mounjaro uses a step-up dosing schedule where you start low and gradually increase every 4 weeks. You cannot jump straight to 15mg — your body needs time to adjust to each dose.
- Weeks 1–4: 2.5mg per week (starting dose)
- Weeks 5–8: 5mg per week
- Weeks 9–12: 7.5mg per week
- Weeks 13–16: 10mg per week
- Weeks 17–20: 12.5mg per week
- Week 21 onwards: 15mg per week (maximum/golden dose)
Each dose comes in a pre-filled KwikPen device — a convenient auto-injector pen. You take exactly one injection per week, always on the same day. If you're tolerating each dose well and your prescriber agrees, you progress to the next level. Some people stay on lower doses if they're achieving good results or experiencing side effects — the golden dose isn't necessary for everyone.
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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.
Using Your Mounjaro KwikPen Correctly
Your Mounjaro KwikPen injection is simple to use. Inject once weekly into your stomach (abdomen), upper thigh, or upper arm — rotate injection sites each week to prevent skin irritation. Before injecting, remove the pen from the fridge 15 minutes beforehand and let it reach room temperature. Check the liquid is clear (not cloudy). Pinch the skin, push the needle in at a 90-degree angle, and press the injection button until you hear a click. Hold for 3 seconds, then withdraw. Dispose of used pens safely in a sharps bin. Always follow your prescriber's guidance on progression — reaching 15mg depends on tolerating side effects and meeting your health goals, not on a fixed timeline.
- 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 is the golden dose of Mounjaro?
The golden dose is 15mg, the maximum weekly dose of Mounjaro (tirzepatide) available in the UK. This is reached after a 20-week gradual titration from 2.5mg, allowing your body to adjust. Not everyone needs 15mg — many people achieve weight loss results on lower doses like 10mg or 12.5mg.
How long does it take to reach the 15mg dose?
Approximately 20 weeks (5 months) if you progress through each dose increase every 4 weeks without stopping. This schedule allows your body to adjust and helps minimise nausea and other side effects. Your prescriber may pause progression if you experience significant side effects.
Can I skip doses or jump straight to 15mg?
No. The titration schedule must be followed as prescribed. Jumping doses increases the risk of severe nausea, vomiting, and other side effects. Mounjaro is designed to be stepped up gradually, giving your system time to adapt at each level.
Do I need to reach 15mg for weight loss to work?
No. Clinical evidence shows weight loss occurs at all doses — 5mg, 10mg, 12.5mg, and 15mg all support weight reduction. Your prescriber will recommend the dose that works best for your individual health and tolerability. Higher dose does not always mean better results.
What should I do if I can't tolerate progressing to the next dose?
Inform your prescriber immediately. You may stay on your current dose longer, pause progression, or reduce back to a lower dose if side effects are severe. Weight loss injections should support your health — not cause suffering. Your prescriber can adjust the plan to suit you.
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.