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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Mounjaro Maintenance Dose UK vs Wegovy — Full Comparison
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription weight loss injections licensed in the UK, but they work through different mechanisms and reach different maintenance doses. Mounjaro's dual GIP and GLP-1 action allows a higher maximum dose of 15 mg weekly, while Wegovy's single GLP-1 mechanism reaches 2.4 mg weekly. Understanding the differences in dosing, clinical trial results, and how each reaches maintenance can help you and your prescriber decide which suits your individual health needs.
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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.
Maintenance Dose Comparison: Trial Data and Mechanisms
Mounjaro (tirzepatide) reaches maintenance at 15 mg once weekly, typically after 5 months of dose escalation starting from 2.5 mg. The SURMOUNT-1 clinical trial showed average weight loss of approximately 20.9% of body weight at the 15 mg maintenance dose over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) reaches maintenance at 2.4 mg once weekly, typically after 16 weeks of escalation starting from 0.25 mg. The STEP-1 clinical trial demonstrated average weight loss of approximately 14.9% of body weight at 2.4 mg maintenance over 68 weeks under similar lifestyle conditions.
The key difference: Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two separate hormone pathways. Wegovy is a GLP-1 receptor agonist only, stimulating a single pathway. This dual mechanism in Mounjaro may explain the higher average weight loss in trials, though individual results vary significantly and depend on factors including starting weight, adherence, diet, and exercise.
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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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Individual Suitability and Prescriber Assessment
Both Mounjaro and Wegovy are prescription-only medicines available in the UK through NHS specialist weight management services or private online prescribing following clinical assessment. Your prescriber will consider your individual health profile, including BMI, weight-related conditions such as type 2 diabetes or high blood pressure, any medications you take, and your personal health goals.
Eligibility criteria are the same for both: typically a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions. Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. Neither medication is suitable during pregnancy or whilst breastfeeding, and both require commitment to lifestyle changes for optimal results. Use our free GLP-1 weight loss calculator to explore potential outcomes, or calculate your BMI using our weight converter and BMI tools to understand your starting point.
- 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 maximum maintenance dose of Mounjaro in the UK?
The maximum maintenance dose of Mounjaro in the UK is 15 mg once weekly. Most patients reach this dose after approximately 20 weeks of gradual escalation from 2.5 mg, increasing by 2.5 mg every four weeks. The dose is adjusted based on tolerance and response.
How long does it take to reach maintenance dose on Wegovy?
Wegovy typically reaches maintenance dose (2.4 mg) after 16 weeks of escalation, starting from 0.25 mg and increasing weekly through intermediate doses of 0.5 mg, 1 mg, and 1.7 mg. The full escalation schedule is slower than Mounjaro's.
Which injection lost more weight in clinical trials — Mounjaro or Wegovy?
In clinical trials, Mounjaro showed average weight loss of approximately 20.9% body weight at maintenance, while Wegovy showed approximately clinically studied weight loss. However, individual results vary significantly, and these are trial averages alongside reduced-calorie diet and exercise.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between medications requires prescriber guidance. There is no official conversion chart, but approximate equivalences exist (e.g., Wegovy 2.4 mg is roughly equivalent to Mounjaro 10–15 mg). Any switch must be managed by your healthcare provider to ensure safety.
Is Mounjaro or Wegovy better for weight loss?
Neither is universally "better" — suitability depends on your individual health profile, tolerance, and prescriber assessment. Mounjaro's dual mechanism may support greater average weight loss, but Wegovy may suit others equally well. Your GP or prescriber will advise which aligns with your health needs.
Ready to take control of your weight loss journey?
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