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 Mounjaro 7.5mg Equivalent to Wegovy?
Mounjaro 7.5mg and Wegovy are not directly equivalent, though approximate dose comparisons exist. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1-only medication. Both are prescription-only weight management injections licensed in the UK, but their different mechanisms and dosing schedules mean direct comparison is complex. This guide explains the differences and helps you understand what these doses mean in clinical context. Use our free BMI calculator and GLP-1 weight loss calculator to explore your personal health picture alongside any discussion with your prescriber.
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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.
Mounjaro and Wegovy: Mechanism and Dose Differences
Mounjaro (tirzepatide): A dual GIP and GLP-1 receptor agonist with doses ranging from 2.5mg to 15mg once weekly. The 7.5mg dose is typically an escalation step during titration, usually reached by weeks 9–12 of treatment. Mounjaro's dual mechanism activates two separate hormone pathways, which may contribute to its stronger appetite suppression in some clinical contexts.
Wegovy (semaglutide): A single GLP-1 receptor agonist with doses from 0.25mg to 2.4mg once weekly. Wegovy reaches its maximum therapeutic dose (2.4mg) by week 17 of titration.
Approximate equivalence: Clinical practice suggests Mounjaro 7.5mg approximates to Wegovy 1.7mg in terms of glycaemic control, though weight loss outcomes vary individually. This is not an official conversion—any medication switch must be managed by your prescriber. Both are prescribed via prescription-only status following clinical assessment by a UK-licensed healthcare professional.
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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.
Clinical Trial Context and Individual Suitability
Mounjaro's SURMOUNT-1 trial showed average weight loss of approximately 19.5% at the 10mg dose and 20.9% at 15mg over 72 weeks. Wegovy's STEP-1 trial demonstrated approximately clinically studied weight loss at the maximum 2.4mg dose over 68 weeks. These results were achieved alongside reduced-calorie diet and increased physical activity—individual results vary significantly. Neither medication is "better"; suitability depends on your personal health history, other medications, and prescriber assessment. Your GP or specialist weight management service can evaluate whether Mounjaro or Wegovy is more appropriate for you based on your BMI, health conditions, and clinical factors. Track your progress with our free progress tracker once treatment begins.
- 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 7.5mg the same strength as Wegovy 1.7mg?
They are approximate clinical equivalents used in practice, but not officially interchangeable. Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is GLP-1-only. Different mechanisms mean results vary by individual. Any switch between medications must involve your prescriber.
What does GIP mean in Mounjaro?
GIP (glucose-dependent insulinotropic polypeptide) is a second hormone pathway that Mounjaro activates alongside GLP-1. This dual action may enhance appetite suppression and metabolic effects compared to GLP-1-only medications like Wegovy.
How long does it take to reach Mounjaro 7.5mg?
Mounjaro titration typically takes 9–12 weeks to reach 7.5mg, starting at 2.5mg and increasing by 2.5mg every 4 weeks. Your prescriber may adjust this schedule based on your tolerability and response.
Can I switch from Wegovy to Mounjaro 7.5mg?
Switching between GLP-1 medications is possible but must be managed by your prescriber. There is no standard automatic conversion. Your GP or weight management specialist will assess whether a switch is appropriate and manage the transition safely.
Which causes more side effects—Mounjaro 7.5mg or Wegovy?
Both can cause nausea, stomach upset, and appetite changes. Side effect profiles are similar overall. Individual tolerance varies. Discuss any side effects with your prescriber—dose adjustments or medication choice may help manage tolerability.
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.