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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Understanding Mounjaro's Golden Dose and How to Use It
The term "golden dose" often refers to the optimal Mounjaro dose where weight loss benefits plateau, typically at 10–15 mg once weekly. Mounjaro (tirzepatide) is a prescription-only, once-weekly GLP-1 and GIP receptor agonist injection licensed in the UK for weight management in adults. Unlike single-mechanism injections, Mounjaro's dual action on GLP-1 and GIP pathways may produce different results than Wegovy. Your GP or licensed prescriber will determine the right dose for you based on individual health factors and tolerance. This guide explains how Mounjaro dosing works and how it compares to alternative weight loss treatments.
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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.
How Mounjaro Dosing and the Golden Dose Work
Mounjaro starts at 2.5 mg once weekly and increases gradually every 4 weeks: 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg as the maximum dose. The "golden dose" concept suggests that weight loss benefits level off around 10–15 mg, though individual responses vary significantly. In the SURMOUNT clinical trials, participants on 10 mg lost approximately 19.5% of body weight on average, whilst those on 15 mg achieved around 20.9%—a modest difference. Your prescriber may stabilise you at a lower dose if you experience good results and tolerate it well, as higher doses do not assures better outcomes and side effects can increase. Dose increases happen every 4 weeks minimum, allowing your body to adjust. Using your Mounjaro KwikPen correctly means injecting once weekly into the stomach, thigh, or upper arm, rotating sites each week. Missed doses within 4 days can still be taken on schedule; beyond 4 days, skip and resume your normal weekly day.
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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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Mounjaro Dosing Compared to Wegovy: Key Differences
Wegovy (semaglutide) uses a different dosing schedule: 0.25 mg starting dose increasing to 2.4 mg maximum. Mounjaro's dual GIP and GLP-1 mechanism differs from Wegovy's single GLP-1 action, meaning dose-for-dose comparisons are not straightforward. Clinical trials showed Mounjaro participants achieved approximately 15–clinically studied weight loss (SURMOUNT), whilst Wegovy participants achieved around 15% (STEP trials). The "golden dose" concept applies to both: higher doses do not always yield proportionally better results, and individual suitability depends on your health profile, tolerance to side effects, and how your body responds. Both are prescription-only and require a clinical assessment. Neither medication should be started or switched without prescriber guidance. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses, though remember all results are averages and individual weight loss varies considerably.
- 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 exactly is the "golden dose" for Mounjaro?
The "golden dose" is an informal term suggesting the dose where weight loss benefits plateau—typically 10–15 mg for Mounjaro. However, no single dose is optimal for everyone. Your prescriber will determine the right dose based on your tolerance, side effects, and personal health. Some people achieve excellent results at lower doses; others may need higher doses. The "golden" dose is the one that works best for you with manageable side effects.
How does Mounjaro's dosing differ from Wegovy?
Mounjaro starts at 2.5 mg and increases to 15 mg maximum, whilst Wegovy begins at 0.25 mg and reaches 2.4 mg. Mounjaro uses a dual GIP and GLP-1 mechanism; Wegovy uses GLP-1 only. These differences mean direct dose comparisons are not possible. Clinical trials showed similar average weight loss outcomes (~15–21%), but individual responses differ. Only your prescriber can advise which is suitable for you.
Can I skip a Mounjaro dose or adjust my schedule?
If you miss a dose within 4 days of your scheduled injection day, take it as soon as you remember and continue your normal weekly schedule. If more than 4 days have passed, skip that dose and resume on your regular day. Never take a double dose or adjust your schedule without consulting your prescriber. Consistency is important for best results.
What happens if I experience side effects at my current Mounjaro dose?
Common side effects (nausea, diarrhoea, constipation) often improve within 1–2 weeks as your body adjusts. If they persist or are severe, contact your prescriber—they may pause your dose escalation or reduce your dose temporarily. Do not stop suddenly without medical guidance. Your prescriber may recommend dietary adjustments or other strategies to manage side effects whilst you stabilise.
Is Mounjaro available on the NHS in the UK?
Yes, Mounjaro is approved by NICE for use within NHS specialist weight management services (tier 3/4). However, NHS access is limited and varies significantly by region. Many people access Mounjaro privately through a GPhC-registered online pharmacy following a clinical assessment. Eligibility criteria are the same for both routes (BMI ≥30, or BMI 27–29.9 with weight-related health conditions). Your GP can refer you to NHS specialist services, or you can pursue private assessment.
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