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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What's the Highest Mounjaro Dosage Compared to Wegovy?
Mounjaro and Wegovy are both prescription-only weight management injections available in the UK, but they reach different maximum doses. Mounjaro's highest dose is 15mg once weekly, while Wegovy tops out at 2.4mg once weekly. Both medications work through different mechanisms and show different weight loss results in clinical trials. Your GP or prescriber will assess which is suitable for you based on your individual health, eligibility, and response to treatment. Understanding the dosage differences helps you have informed conversations with your healthcare team about what to expect.
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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.
Mounjaro vs Wegovy: Maximum Doses and Clinical Trial Results
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways, which distinguishes it from single-mechanism medications. The highest Mounjaro dosage is 15mg once weekly, reached over approximately 20 weeks of gradual dose titration starting from 2.5mg. In the SURMOUNT-1 clinical trial, participants on 15mg Mounjaro lost an average of approximately 20.9% of their body weight over 72 weeks, alongside reduced-calorie diet and increased physical activity. Individual results vary significantly.
Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates a single hormone pathway. The maximum Wegovy dose is 2.4mg once weekly, reached over approximately 16 weeks starting from 0.25mg. In the STEP-1 clinical trial, participants on 2.4mg Wegovy lost approximately 14.9% of their body weight over 68 weeks, again alongside lifestyle changes. Both are available on prescription in the UK through NHS specialist services or private prescribing following clinical assessment.
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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.
Which Medication Might Suit You? Individual Assessment is Key
Neither medication is universally "better" — suitability depends on your personal health profile, medical history, and how you respond to treatment. Your prescriber will assess eligibility based on BMI, weight-related health conditions, and any contraindications. Some people respond better to dual-mechanism medications like Mounjaro; others achieve excellent results with single-mechanism Wegovy. Dose titration schedules differ too: Mounjaro requires longer titration (20 weeks to reach 15mg) versus Wegovy (16 weeks to reach 2.4mg). Use our free GLP-1 weight loss calculator to explore projected outcomes at different doses, and discuss your personal suitability with your GP or licensed prescriber before starting any medication.
- 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 15mg Mounjaro more effective than 2.4mg Wegovy because the dose is higher?
Not necessarily. Doses are not directly comparable — Mounjaro and Wegovy use different mechanisms and dosing scales. SURMOUNT-1 data showed approximately clinically studied weight loss on 15mg Mounjaro; STEP-1 showed approximately 14.9% on 2.4mg Wegovy. However, individual results vary significantly. Some people achieve excellent results on Wegovy, while others respond better to Mounjaro. Your prescriber assesses which suits you based on your health profile.
How quickly does Mounjaro reach its highest dose?
Mounjaro dose titration takes approximately 20 weeks to reach the maximum 15mg dose, starting from the initial 2.5mg dose. Each dose level is held for a minimum of 4 weeks before escalation. This gradual approach helps your body adjust and allows your prescriber to monitor side effects and effectiveness before increasing.
Can I switch from Wegovy to Mounjaro if one doesn't work?
Yes, switching between medications is possible, but must be managed by your prescriber. There is no official conversion chart, though approximate equivalences exist (e.g., 2.4mg Wegovy is roughly equivalent to 10–15mg Mounjaro). Any switch requires a new clinical assessment and prescription. Never switch medications without guidance from your healthcare provider.
Are the side effects the same for Mounjaro and Wegovy?
Both share common side effects like nausea, diarrhoea, constipation, and stomach pain — these are typical of GLP-1 medications. Mounjaro, as a dual-mechanism medication, may have a slightly different side effect profile, though both are generally well-tolerated. Discuss potential side effects with your prescriber before starting.
Do I need to reach the highest Mounjaro dose to see weight loss results?
No. Weight loss can occur at lower doses. Many people see meaningful results at 5mg or 10mg Mounjaro and choose to stabilise at those doses. Your prescriber may recommend reaching the highest dose, but individual tolerance and response guide the final dose chosen. Higher doses don't assures better outcomes for everyone.
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.