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 Dosage for Weight Loss in the UK
Mounjaro (tirzepatide) is a once-weekly weight loss injection licensed in the UK for adults with excess weight and weight-related health conditions. It starts at a low dose and increases gradually every 4 weeks to help your body adapt and minimise side effects. The NHS approves tirzepatide for weight management through specialist tier 3 services, though access varies significantly across regions. This guide explains how Mounjaro dosing works, who qualifies under NHS criteria, and the practical steps to access it in the UK.
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.
How Mounjaro Dosage Works in the UK
Mounjaro is delivered as a once-weekly injection using a pre-filled KwikPen device. The dosing schedule starts low and increases gradually — a process called dose titration. Each dose is held for at least 4 weeks before increasing to the next level:
- Weeks 1–4: 2.5 mg (starting dose)
- Weeks 5–8: 5 mg (first escalation)
- Weeks 9–12: 7.5 mg
- Weeks 13–16: 10 mg
- Weeks 17–20: 12.5 mg
- Week 21+: 15 mg (maximum dose)
This gradual increase helps your body adjust and allows your prescriber to find the lowest effective dose for you. Clinical trial data from SURMOUNT-1 showed that at 15 mg weekly, participants lost an average of approximately 20.9% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. However, individual results vary significantly — some people see good results at lower doses. Try our free GLP-1 weight loss calculator to estimate potential results 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.
NHS Eligibility and Access for Mounjaro in the UK
The NICE (National Institute for Health and Care Excellence) has approved tirzepatide for weight management within the NHS, but access is through specialist tier 3 weight management services, not standard GP prescriptions. You qualify if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, eligibility thresholds are lower (BMI 27.5+). NHS availability varies by region — some areas have waiting lists of many months. Many UK patients access Mounjaro privately through GPhC-registered online prescribing services, which offer faster access following a clinical assessment. Check your personal BMI using our free BMI calculator to understand your eligibility 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.
What's the starting dose of Mounjaro for weight loss in the UK?
The starting dose is 2.5 mg once weekly for the first 4 weeks. This low starting dose helps your body adapt to the medication and reduces side effects. Your prescriber will increase the dose every 4 weeks if it's working well and you're tolerating it — up to a maximum of 15 mg weekly. The exact escalation schedule may vary based on your individual response.
Can I stay on a lower dose of Mounjaro, or do I need to reach 15 mg?
No, you don't need to reach the maximum dose. Many people see good weight loss results at doses like 5 mg, 7.5 mg, or 10 mg weekly. Your prescriber will work with you to find the lowest effective dose that gives you results without troublesome side effects. There's no requirement to escalate to 15 mg if you're doing well on a lower dose.
How does Mounjaro dosage compare to Wegovy?
Mounjaro and Wegovy are different medications with different dose ranges. Mounjaro goes up to 15 mg, while Wegovy goes up to 2.4 mg — but they're not directly comparable because they use different mechanisms. Mounjaro is a dual GIP/GLP-1 agonist, while Wegovy is GLP-1 only. Average weight loss results are similar in clinical trials, but individual outcomes vary. Your prescriber will recommend whichever suits your health profile.
Is Mounjaro available on the NHS in my area?
Mounjaro is approved by NICE for NHS use, but availability varies significantly by region because it's prescribed through specialist tier 3 weight management services. Some areas have limited services or long waiting lists. Your GP can refer you to your local service, or you can check your ICB's (Integrated Care Board) guidelines online. Many people choose private access for faster availability.
What if I miss a Mounjaro injection dose?
If you're within 4 days of your scheduled injection, take it as soon as you remember and continue your normal weekly schedule. If more than 4 days have passed, skip that dose and inject on your next regular day. Never take two doses within 3 days of each other. Contact your prescriber or pharmacist if you're unsure about the timing.
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.