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
How to Get Mounjaro Through Your GP on the NHS
If you're interested in Mounjaro (tirzepatide) as a weight management option in the UK, your GP is the right starting point — but the NHS pathway works differently than prescription antibiotics. Unlike straightforward GP prescriptions, Mounjaro access through the NHS typically involves referral to specialist tier 3 weight management services. This guide explains the NHS eligibility criteria, how the NICE-approved pathway works, and what to expect when you approach your GP about tirzepatide treatment.
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.
NHS Eligibility and the Tier 3 Referral Pathway
The NHS approves Mounjaro (tirzepatide) for weight management, but access is controlled through NICE guidelines and specialist tier 3 services, not routine GP prescription. Your GP cannot simply prescribe it; they must refer you to your local tier 3 weight management service for assessment.
You may be eligible for NHS Mounjaro 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 (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, cardiovascular disease, or abnormal blood lipids)
- For adults of South Asian, Chinese, Black African, or Black Caribbean heritage: lower thresholds apply (BMI 27.5 or above)
After referral, the tier 3 service will conduct a full clinical and psychological assessment, review your medical history, and check whether tirzepatide is appropriate for you. This process ensures the medication is safe and suitable for your individual circumstances.
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 vs Private Routes — What's the Difference?
The NHS route is free at the point of use but involves specialist referral, assessment, and potential waiting lists (which vary significantly by region — some areas have waits of months). The private route involves an online consultation with a UK-licensed prescriber, typically faster access (sometimes within days), but requires payment per dose (usually £150–£300/month depending on your dose).
Eligibility criteria are similar for both routes. The key difference is speed and cost. If you're eligible and your local NHS service has capacity, NHS access is cost-free. If waiting lists are long or you prefer faster access, private prescribing is available through registered UK pharmacies following a clinical assessment. Use our free GLP-1 weight loss calculator to explore potential outcomes, and discuss both pathways with your GP.
- 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.
Can my GP prescribe Mounjaro directly?
Not usually. Your GP can initiate the referral, but Mounjaro prescriptions come from NHS specialist tier 3 weight management services, not routine GP practices. Some integrated care boards (ICBs) have different arrangements, so ask your GP about your local pathway.
How long are NHS waiting lists for Mounjaro?
Waiting times vary significantly by region. Some areas have waits of 3–6 months, others longer. Contact your local tier 3 weight management service for current waiting times in your area.
What happens at the NHS assessment appointment?
The specialist team will review your weight history, medical conditions, medications, mental health, and lifestyle. They'll check whether tirzepatide is safe for you, discuss side effects, explain the injection technique, and confirm your commitment to dietary and lifestyle changes alongside medication.
Is Mounjaro available on the NHS everywhere in the UK?
NICE has approved tirzepatide for NHS use, but regional availability and commissioning vary. Some ICBs have good access; others may have restrictions based on funding. Your GP can check what's available in your area.
Can I switch between NHS and private Mounjaro?
Technically yes, but it's not recommended mid-treatment. If you start on the NHS and waiting lists are lengthy, you can explore private access independently. If you're on private tirzepatide, you cannot automatically switch to NHS supply — each route requires separate assessment and 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.