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
Free tracker included with every download this week
Mounjaro vs Wegovy: Dosing Schedule Comparison
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are once-weekly prescription injections for weight management in UK adults, but they follow different dosing schedules and reach different maximum doses. Understanding the differences between the two tirzepatide and GLP-1 options can help you discuss which might be more suitable for your circumstances with your prescriber. This guide compares the schedules, mechanisms, and key differences based on clinical evidence.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 vs Wegovy: Dosing Schedules and Trial Data
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist licensed for UK weight management. The schedule involves:
- Starting dose: 2.5 mg once weekly for weeks 1–4
- Escalation: increasing by 2.5 mg every 4 weeks if tolerated
- Maximum dose: 15 mg once weekly
- Clinical context: SURMOUNT-1 trial showed average weight loss of approximately 20.9% body weight at the 15 mg dose over 72 weeks
Wegovy (semaglutide) is a GLP-1-only receptor agonist with a slower dose titration:
- Starting dose: 0.25 mg once weekly for weeks 1–4
- Escalation: stepping up through 0.5 mg, 1 mg, and 1.7 mg at 4-week intervals
- Maximum dose: 2.4 mg once weekly
- Clinical context: STEP-1 trial showed average weight loss of approximately 14.9% body weight at 68 weeks on the 2.4 mg dose
Both schedules involve multiple dose adjustments over several months, and individual progression depends on tolerance and clinical response. Use our GLP-1 weight loss calculator to estimate potential outcomes at different dose levels.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Mechanism Differences and Individual Suitability
The key difference between the two medications is their mechanism: Mounjaro activates both GIP and GLP-1 pathways (dual agonist), whilst Wegovy targets GLP-1 only. This dual action in Mounjaro may contribute to the higher average weight loss seen in clinical trials, though individual results vary significantly. Neither schedule is automatically "better"—suitability depends on your personal health profile, medical history, and how your body responds during the dose titration phase.
Both medications require a UK prescription following a clinical assessment by a licensed prescriber. Your GP or specialist will review your BMI, weight-related health conditions, and current medications to determine which dosing schedule is appropriate for you. If one medication doesn't suit you, switching to the other is a prescriber decision based on your individual circumstances. Track your progress with our free progress tracker once you've started treatment.
- 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.
What is the difference between Mounjaro and Wegovy dosing schedules?
Mounjaro starts at 2.5 mg and increases by 2.5 mg every 4 weeks up to 15 mg maximum. Wegovy starts at 0.25 mg and escalates more gradually through 0.5 mg, 1 mg, 1.7 mg, to 2.4 mg maximum. Mounjaro reaches a higher absolute dose and may reach maximum sooner, whilst Wegovy has a slower, lower-dose progression.
Why is Mounjaro's average weight loss higher than Wegovy's?
Clinical trials showed Mounjaro (SURMOUNT) averaging clinically studied weight loss versus Wegovy (STEP) at 14.9%. This difference is attributed to Mounjaro's dual GIP and GLP-1 mechanism compared to Wegovy's GLP-1-only action. However, individual results vary—some people respond better to one than the other.
Can I switch from Wegovy to Mounjaro or vice versa?
Yes, but any switch must be managed by your prescriber. There is no official dose equivalence chart, though approximate comparisons exist. Your prescriber will assess your response to the current medication and decide if switching is appropriate.
How long does the dosing schedule take to complete?
Mounjaro typically reaches maximum dose in approximately 16–20 weeks (four 4-week escalation steps). Wegovy takes slightly longer, usually 16–20 weeks as well due to smaller incremental increases. Both then continue on the maintenance dose indefinitely.
Do I need a prescription to access either Mounjaro or Wegovy in the UK?
Yes, both are prescription-only medicines in the UK. Access is through NHS specialist weight management services or private prescribing following an online clinical assessment. Your prescriber will confirm eligibility before issuing a prescription.
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.