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
Understanding Mounjaro Bundles in the UK
A Mounjaro bundle in the UK typically refers to a starter pack containing multiple pre-filled KwikPens at graduated doses, designed to help you reach your maintenance dose over several weeks. Mounjaro (tirzepatide) is a prescription-only, once-weekly weight loss injection licensed in the UK. Access is available through NHS specialist weight management services or private prescribing following clinical assessment. Understanding the bundle structure, dosing schedule, and eligibility criteria helps you prepare for treatment. Use our free BMI calculator above to check your current BMI against NHS thresholds.
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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.
NHS Eligibility and Mounjaro Access in the UK
NHS eligibility for tirzepatide (Mounjaro): NICE has approved Mounjaro for weight management in UK adults meeting specific criteria. You may be eligible if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — eligibility may start at BMI 27.5 or above due to higher health risks at lower weights.
- NHS access route: Referral from your GP to a tier 3 specialist weight management service
- Assessment: Specialist team assesses suitability based on your health history and BMI
- Prescription: If approved, Mounjaro is prescribed through the NHS specialist service
- Regional variation: Availability varies significantly across England, Scotland, Wales, and Northern Ireland — some areas have waiting lists of several months
A Mounjaro bundle typically contains four pre-filled pens covering the first four weeks of treatment, starting at the 2.5 mg dose.
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.
Mounjaro Bundle Dosing & Private Access
The standard Mounjaro bundle includes four KwikPens at 2.5 mg (one per week for weeks 1–4), allowing you to begin treatment safely. After four weeks, your prescriber increases the dose to 5 mg and continues escalating every 4 weeks — up to a maximum of 15 mg — based on your response and tolerability. In clinical trials, Mounjaro helped participants lose an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
Private route: Outside NHS services, Mounjaro is available through GPhC-registered online pharmacies following a consultation with a UK-licensed prescriber. This route does not require NHS referral and may have shorter waiting times. Try our GLP-1 weight loss calculator to estimate potential outcomes at different doses, and track your progress with our free progress tracker.
- 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 a Mounjaro bundle and how long does it last?
A Mounjaro bundle is a starter pack containing four pre-filled KwikPens, each at 2.5 mg, covering your first four weeks of treatment. Each pen is injected once weekly. After four weeks, your prescriber typically increases your dose to 5 mg and continues escalating every 4 weeks based on your individual response, up to a maximum of 15 mg weekly.
Am I eligible for Mounjaro on the NHS in the UK?
You may be eligible if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with a weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, cardiovascular disease). South Asian, Chinese, Black African, or Black Caribbean adults may be eligible from a BMI of 27.5 or above. Your GP can refer you to a tier 3 specialist weight management service for assessment.
What's the difference between NHS and private Mounjaro access in the UK?
NHS access requires a GP referral to a specialist service and has regional waiting lists, sometimes several months long. Private access is through GPhC-registered online pharmacies with a UK-licensed prescriber consultation, typically faster but involves out-of-pocket costs. Both routes require clinical assessment; both are prescription-only.
How much weight can I expect to lose with Mounjaro?
Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks — though individual results vary significantly. Weight loss depends on dose, diet, physical activity, and personal factors. Use our free GLP-1 weight loss calculator to estimate potential outcomes. Results are not assured, and lifestyle changes remain essential alongside medication.
How is a Mounjaro bundle stored and used?
Unopened KwikPens should be stored in a refrigerator at 2–8°C in the original carton. Once you start using a pen, it can be kept at room temperature (below 30°C) for up to 30 days. Inject once weekly into your stomach, thigh, or upper arm, rotating injection sites. Dispose of each pen 30 days after first use, even if not empty.
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.