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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Tirzepatide 10mg vs Wegovy: How Do They Compare?
If you're exploring weight loss medication options in the UK, you may have heard about both tirzepatide (sold as Mounjaro) and Wegovy (semaglutide). At the 10mg dose, tirzepatide works differently from Wegovy and shows different clinical outcomes. This guide explains the key differences between these two prescription weight loss injections, the evidence behind them, and how prescribers decide which might be suitable. Both are licensed for weight management in UK adults and require a clinical assessment before prescription.
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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 Tirzepatide 10mg and Wegovy Work Differently
The most important difference between tirzepatide and Wegovy is how they work at the hormone level. Tirzepatide is a dual GIP and GLP-1 receptor agonist — it activates two separate hormone pathways simultaneously, whereas Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating a single pathway.
This dual mechanism may explain why tirzepatide shows higher average weight loss in clinical trials. In the SURMOUNT-1 trial, tirzepatide 10mg helped participants lose approximately 19.5% of their body weight on average over 72 weeks. By comparison, in the STEP-1 trial, Wegovy 2.4mg (the maximum dose) achieved approximately clinically studied weight loss at 68 weeks.
However, individual results vary significantly. Some people respond better to one mechanism than the other. Both medications also slow gastric emptying (how quickly food leaves the stomach), reduce appetite signals to the brain, and support feeling fuller after smaller meals. The choice between them depends on your individual health, previous medication responses, and your prescriber's clinical judgment.
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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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Doses, Side Effects, and Choosing Between Them
At the 10mg dose, tirzepatide is administered once weekly via a pre-filled KwikPen. Wegovy's maximum dose is 2.4mg weekly — tirzepatide's 10mg dose is roughly equivalent to Wegovy's 1.7mg in terms of potency, though this is approximate and not an official conversion.
Common side effects are similar for both: nausea, diarrhoea, constipation, and stomach pain are most frequent. Both require a minimum 4-week interval between dose increases, and both should be used alongside a reduced-calorie diet and increased physical activity.
Your prescriber will assess which is more suitable based on your medical history, whether you have type 2 diabetes, any previous GLP-1 medication experience, and individual tolerability. Access through the NHS or private prescription both require clinical assessment. Use our free GLP-1 weight loss calculator to explore projected outcomes with different doses, and our BMI calculator to understand your current weight status.
- 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 tirzepatide 10mg stronger than Wegovy?
Tirzepatide 10mg shows higher average weight loss in clinical trials (~19.5%) compared to Wegovy 2.4mg (~14.9%), likely due to its dual GIP+GLP-1 mechanism versus Wegovy's single GLP-1 pathway. However, "stronger" varies by individual — some people respond better to one than the other.
Can I switch from Wegovy to tirzepatide 10mg?
Yes, switching is possible under medical supervision. There is no official conversion chart, but 10mg tirzepatide is approximately equivalent to 1.7mg Wegovy in potency. Your prescriber will manage any switch, typically with a transition period to monitor tolerability.
Which one is available on the NHS?
Both tirzepatide (Mounjaro) and Wegovy are approved by NICE for NHS specialist weight management services. Access depends on your local integrated care board (ICB) and referral through tier 3 services. Private access is available through prescription if not available on the NHS in your area.
What's the difference in injection frequency?
Both tirzepatide and Wegovy are once-weekly injections. Liraglutide (Saxenda) is the only UK-licensed weight loss GLP-1 injection that requires daily dosing. Mounjaro and Wegovy are equally convenient in terms of injection schedule.
Who decides whether I get tirzepatide or Wegovy?
Your GP or the prescriber conducting your clinical assessment will decide based on your individual health profile, BMI, weight-related health conditions, medical history, and medication tolerability. Both require prescription and clinical assessment — neither is available without prescriber evaluation.
Ready to take control of your weight loss journey?
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