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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Do You Lose More Weight On 5mg Mounjaro Compared To Wegovy?
The short answer is: individual results vary significantly, and both Mounjaro and Wegovy can support meaningful weight loss. At the 5mg Mounjaro dose, clinical trials showed average weight loss of around 15% body weight over 72 weeks. Wegovy at equivalent doses showed similar results in the STEP trials. The key difference isn't necessarily which one produces more weight loss, but how your body responds to the specific mechanism. Both are prescription-only medications requiring clinical assessment. Your GP or prescriber will recommend the most suitable option based on your individual health profile and preferences.
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Calculate Your BMI Instantly
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.
Clinical Trial Data: 5mg Mounjaro vs Wegovy Weight Loss
Mounjaro (tirzepatide) at 5mg: The SURMOUNT-1 trial showed participants lost an average of approximately 15% of their body weight at this dose over 72 weeks, alongside a reduced-calorie diet and increased physical activity. For example, a person weighing 100kg might lose around 15kg on average.
Wegovy (semaglutide) at equivalent dose: The STEP-1 trial demonstrated average weight loss of approximately 14.9% body weight at 68 weeks on semaglutide 2.4mg — the closest comparative dose. Results were similarly achieved with diet and exercise changes.
- Both show comparable average weight loss percentages at lower-to-mid doses
- Individual results vary — some people lose significantly more or less
- Results depend on adherence, diet, exercise, and metabolism
- Weight loss is gradual, typically most noticeable after 12–16 weeks
The key insight: at 5mg Mounjaro, the average weight loss is comparable to Wegovy, not necessarily greater. The choice between them depends on other factors, not just projected weight loss.
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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.
Why Results Vary: Mechanism, Dose, And Individual Suitability
Mounjaro works as a dual GIP and GLP-1 receptor agonist — activating two hormone pathways simultaneously. Wegovy is a GLP-1 agonist only — a single mechanism. This difference doesn't automatically mean more weight loss on Mounjaro; it means your body may respond differently depending on your individual hormone sensitivity and metabolism.
At 5mg, Mounjaro is still in the dose titration phase — your prescriber will assess how you respond before escalating to higher doses (7.5mg, 10mg, 12.5mg, 15mg). Wegovy follows a similar gradual escalation. Individual suitability matters more than dose alone: a weekly weight loss injection works best alongside genuine diet and lifestyle changes. Use our GLP-1 weight loss calculator to explore projected outcomes, and discuss with your prescriber which medication aligns with your health goals.
- 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.
Will I lose more weight on 5mg Mounjaro than Wegovy?
Clinical trial data shows comparable average weight loss — approximately 15% with Mounjaro 5mg and 14.9% with Wegovy at equivalent doses. However, individual results vary significantly based on metabolism, diet, exercise, and medication adherence. Your prescriber can discuss which is more suitable for you personally.
How quickly will I see weight loss results on 5mg Mounjaro?
Most people begin noticing weight changes after 4–8 weeks, with more significant results visible by 12–16 weeks. Weight loss is gradual and steady — rapid results are not typical and may indicate unsustainable practices. Aim for 0.5–1kg per week as a safe, sustainable rate.
Is 5mg the maximum dose of Mounjaro for weight loss?
No. 5mg is the first maintenance dose. Your prescriber may escalate to 7.5mg, 10mg, 12.5mg, or the maximum 15mg depending on your response and tolerance. Each dose increase is typically given every 4 weeks to assess safety and effectiveness.
Can I switch from Wegovy to Mounjaro if I'm not seeing enough weight loss?
Switching between medications requires GP or prescriber guidance — never switch without clinical assessment. Your prescriber will evaluate your response, side effects, and suitability before recommending a change. There is no official standard conversion between the medications, so any switch must be managed carefully.
What should I do to maximise weight loss on 5mg Mounjaro or Wegovy?
Both medications work best alongside a reduced-calorie diet, increased physical activity, and consistent adherence. Track your progress using a weight loss tool, stay hydrated, and maintain regular check-ins with your prescriber. These medications support weight loss but are not replacements for lifestyle change.
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.