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 Your Mounjaro Plan in the UK
A Mounjaro plan outlines how tirzepatide is prescribed and used in the UK for weight management. On the NHS, access happens through specialist tier 3 weight management services following NICE approval. Privately, prescribers work with you to establish a personalised dosing plan starting at 2.5 mg and increasing weekly until you reach an effective maintenance dose—typically 10 mg or 15 mg. This guide explains NHS eligibility, how the tirzepatide dose plan works, and your options for accessing Mounjaro in the UK. Use our free BMI calculator above to check your starting point before exploring whether Mounjaro might be suitable for you.
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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 Mounjaro Eligibility and Tier 3 Services
NHS eligibility for tirzepatide (Mounjaro) is determined by your BMI and health status. You may qualify if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, prediabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease history. For South Asian, Chinese, Black African, and Black Caribbean adults, lower thresholds apply—eligibility may begin at BMI 27.5 or above due to higher metabolic risk at lower weights.
Access on the NHS is through tier 3 specialist weight management services, not standard GP prescription. NICE approved tirzepatide for use within these services, but availability varies significantly by region and waiting lists can be substantial. Your GP can refer you to your local specialist weight management service, though regional differences mean some areas have longer waits than others.
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 Dose Plan and Private Access in the UK
A standard Mounjaro kwikpen dose plan starts at 2.5 mg weekly, increasing every 4 weeks: 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), 10 mg (weeks 13–16), 12.5 mg (weeks 17–20), and up to 15 mg (week 21 onwards). Your prescriber adjusts based on tolerability and weight loss response. Privately, you can access tirzepatide through a UK-licensed prescriber following an online clinical assessment, without NHS referral, though costs typically range from £150–£300 monthly depending on dose.
Whether NHS or private, your plan always pairs tirzepatide with reduced-calorie diet and increased activity. Try our GLP-1 weight loss calculator to estimate potential results at different doses, and track progress using our free progress tracker throughout your plan.
- 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.
How long does a Mounjaro plan typically take to reach maximum dose?
A standard Mounjaro plan takes approximately 20–24 weeks to reach the maximum dose of 15 mg, starting at 2.5 mg and increasing every 4 weeks. However, many people stabilise at 10 mg or 12.5 mg if they achieve good weight loss and tolerance at that level. Your prescriber adjusts your plan based on your individual response.
What's the difference between NHS and private Mounjaro plans in the UK?
NHS plans are delivered through tier 3 specialist weight management services with longer waiting times but no direct cost. Private plans start sooner through online prescribers but involve monthly fees (typically £150–£300 depending on dose). Both follow similar dosing protocols and require lifestyle changes alongside the medication.
Can I switch from Wegovy to Mounjaro on an NHS plan?
Switching between GLP-1 medications on the NHS requires your tier 3 specialist's approval and assessment. Some services may offer the switch if Wegovy hasn't worked well or side effects are problematic. Private prescribers can also manage switches, though this requires a new clinical assessment and prescription.
Does my Mounjaro plan include follow-up appointments?
Yes—both NHS and private plans include regular follow-up appointments (typically monthly or every 4–6 weeks) to monitor weight loss, side effects, and tolerability. Your prescriber or nurse may adjust your dose, offer support for diet and exercise, and check for any health concerns.
What happens after I reach my target weight on Mounjaro?
Once you reach your target weight, your prescriber may maintain you on your current dose long-term, as tirzepatide may help prevent weight regain. Some people gradually reduce dose under medical supervision. Your plan will include discussion about maintenance versus tapering based on your individual goals and response.
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.