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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Is Wegovy 1 mg Equivalent to Mounjaro? Dose Comparison
Wegovy 1 mg and Mounjaro are not directly equivalent — they contain different active ingredients and work through different mechanisms. Wegovy (semaglutide) is a GLP-1 only medication, while Mounjaro (tirzepatide) activates both GIP and GLP-1 pathways. This guide explains how UK prescribers compare these two prescription weight loss injections, what the dose differences mean, and why individual suitability depends on clinical assessment rather than simple dose conversion.
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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.
Understanding Dose Equivalence: SURMOUNT vs STEP Trial Data
There is no official UK dose conversion chart between Wegovy and Mounjaro — they are structurally different medications. However, clinical practice suggests approximate equivalence based on their respective trials:
- Wegovy 0.5 mg may compare loosely to Mounjaro 5 mg in early weight loss effect
- Wegovy 1.7 mg may approximate Mounjaro 10 mg in potency
- Wegovy 2.4 mg (maximum) may align with Mounjaro 15 mg (maximum)
The SURMOUNT trials for tirzepatide showed average weight loss of ~15–21% at maximum dose, while the STEP trials for semaglutide (Wegovy) showed ~14.9% average loss. These figures are from clinical trials using reduced-calorie diet and increased physical activity — individual results vary significantly. Your prescriber will choose a specific medication based on your health profile, not dose equivalence.
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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 These Medications Differ: Mechanism and Prescriber Selection
Mechanism difference: Wegovy activates only the GLP-1 hormone pathway, reducing appetite and slowing gastric emptying. Mounjaro activates both GIP and GLP-1 pathways simultaneously — this dual action is why Mounjaro is sometimes described as potentially more potent, though results vary between individuals.
Clinical choice: Your GP or specialist prescriber will assess your medical history, previous weight loss attempts, and any underlying conditions (like type 2 diabetes or prediabetes) when deciding between them. Neither medication is "better" in absolute terms — suitability is individual. Both require a prescription following a clinical assessment and are available through NHS specialist weight management services or private online prescribing in the UK.
- 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.
Can I switch from Wegovy 1mg to Mounjaro based on dose equivalence?
Not automatically. Any switch between medications must be managed by your prescriber, not based on dose conversion alone. Your prescriber will consider your response to Wegovy, any side effects, and your overall health before recommending a change. If you're considering a switch, discuss it with your GP or the prescriber managing your weight loss.
Which medication caused more weight loss in clinical trials?
In trials, Mounjaro (tirzepatide) showed average weight loss of approximately 15–21% of body weight, while Wegovy (semaglutide) showed approximately 14.9%. However, these are trial averages — individual results vary significantly, and one medication is not assured to work better for you than the other.
Is Mounjaro stronger than Wegovy?
"Stronger" isn't the right comparison. Mounjaro has a dual mechanism (GIP+GLP-1), which may account for slightly higher average weight loss in trials. Wegovy has a single mechanism (GLP-1 only). Which works better for you depends on your individual body, metabolism, and health factors — your prescriber will advise.
How does the UK GLP-1 weight loss calculator help me understand these medications?
Our free GLP-1 weight loss calculator on this page lets you estimate projected weight loss at different doses of both Wegovy and Mounjaro, based on your current weight. This can help you understand the potential range of outcomes, though your actual results will depend on adherence, diet, activity, and individual factors.
Can I get Mounjaro or Wegovy on the NHS in the UK?
Both are available through NHS specialist tier 3 weight management services, though access varies significantly by region and waiting times can be lengthy. Private prescription and dispensing is also available through GPhC-registered pharmacies following an online clinical assessment. Your GP can advise about NHS routes in your area.
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.