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 Weight Loss Graph — Clinical Trial Data
If you're considering Mounjaro (tirzepatide) for weight management, you've likely wondered what results look like in practice. The SURMOUNT clinical trials tracked weight loss progression over 72 weeks, showing how this prescription injection helps participants achieve results when combined with diet and exercise changes. Understanding the data helps you set realistic expectations, though individual results vary significantly based on dose, lifestyle changes, and personal factors. Your GP or prescriber can discuss whether Mounjaro may be suitable for your specific situation.
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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.
SURMOUNT Trial Weight Loss Results by Dose
The SURMOUNT-1 clinical trial followed over 2,500 adults with obesity or overweight with weight-related health conditions for 72 weeks. Participants received either Mounjaro at doses ranging from 5mg to 15mg weekly, or a placebo injection, alongside a reduced-calorie diet and increased physical activity. The results showed clear dose-dependent weight loss:
- 5mg dose: approximately 15% average body weight loss
- 10mg dose: approximately 19.5% average body weight loss
- 15mg dose: approximately 20.9% average body weight loss
These figures represent the proportion of body weight lost, not absolute kilogrammes. For example, a person weighing 100kg losing 20.9% would lose approximately 21kg. The graph pattern shows weight loss begins within the first 4 weeks and continues throughout the 72-week study period. Most significant losses occurred between weeks 12 and 52.
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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.
How Weight Loss Progresses on Mounjaro
Weight loss on Mounjaro isn't immediate — it's gradual and progressive. During the dose escalation phase (weeks 1–20), participants typically lose 1–2kg per week on average, with some weeks showing faster loss and others plateauing slightly. By week 12, most participants show noticeable progress. After reaching the maintenance dose (usually 10mg or 15mg), weight loss continues but may slow to 0.5–1kg per week. Importantly, the graph shows individual variation is substantial — some participants lost significantly more, others less, depending on adherence to diet and exercise changes, metabolism, and other factors. Using our free GLP-1 weight loss calculator can help you estimate potential outcomes based on your starting weight and dose.
- 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 Mounjaro weight loss assured based on the graph?
No. Clinical trial data shows average results, but individual outcomes vary significantly. The graph represents population averages — your personal weight loss depends on your diet adherence, physical activity, dose tolerance, genetics, and other health factors. Your prescriber can discuss realistic expectations for your specific situation.
How quickly does Mounjaro produce weight loss?
Most people see initial weight loss within 4 weeks of starting treatment. Significant progression typically occurs between weeks 8 and 16. The SURMOUNT trial showed continued loss through week 72, though the rate may slow after initial months. Patience and consistent lifestyle changes are important.
Does the 15mg dose always produce the best results?
The trial showed 15mg produced the highest average weight loss (20.9%), but not everyone reaches or tolerates the maximum dose. Some people achieve their weight loss goals at 10mg or lower doses. Prescribers escalate doses gradually over 20 weeks based on your tolerance and response.
What happens to weight loss if you stop Mounjaro?
The SURMOUNT trial didn't extensively cover post-treatment outcomes, but clinical experience suggests weight may gradually return if diet and exercise habits don't change permanently. This is why Mounjaro is used alongside lifestyle modifications, not instead of them.
How does Mounjaro compare to Wegovy on weight loss graphs?
Mounjaro (tirzepatide) and Wegovy (semaglutide) are different medications with different mechanisms. Mounjaro's dual GIP/GLP-1 action showed slightly higher average weight loss (~21% vs ~15% for Wegovy in trials), but both medications require prescription and individual results vary considerably. Your prescriber can discuss which may suit you better.
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.