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
What is the Minimum BMI for Mounjaro in the UK?
In the UK, the minimum BMI for Mounjaro eligibility is generally 30 kg/m² for adults without weight-related health conditions, or 27 kg/m² if you have conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. However, for people of South Asian, Chinese, Black African, or Black Caribbean heritage, NHS guidance recommends lower BMI thresholds — starting at 27.5 kg/m² or even 23 kg/m² depending on ethnicity and health factors. Your GP or a licensed prescriber will assess whether Mounjaro is suitable for you based on your individual circumstances. Use our free BMI calculator above to check your current BMI instantly.
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 BMI Categories and Mounjaro Eligibility
According to NHS guidance, Mounjaro eligibility is based on BMI thresholds and health status:
- BMI 30 or above: Adults with a BMI in the obese range may be considered for Mounjaro, even without weight-related health conditions
- BMI 27–29.9 (overweight) with comorbidities: If you have type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or a history of heart attack or stroke, you may qualify at a lower BMI
- Ethnicity adjustments: For South Asian, Chinese, Black African, and Black Caribbean adults, the NHS recommends using lower BMI thresholds because these groups face higher cardiovascular and metabolic risk at the same BMI as other populations
The healthy BMI range for UK adults is 18.5 to 24.9 according to NHS guidelines, though ethnicity-adjusted thresholds may vary. Mounjaro is prescribed as part of a comprehensive weight management approach, not as a standalone treatment.
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 Weight Management Pathway and How to Access Mounjaro
In the UK, Mounjaro access is available through two main routes. NHS access: Your GP can refer you to a specialist weight management service (tier 3), where a multidisciplinary team will assess your eligibility and prescribe Mounjaro if appropriate. Waiting times vary significantly by region and can be lengthy in many areas. Private access: You can obtain a prescription through a GPhC-registered online prescriber following a clinical assessment, without needing an NHS referral. Either route requires a thorough health assessment — Mounjaro is prescription-only and not suitable for everyone. Your prescriber will discuss whether it's appropriate alongside lifestyle changes including diet and physical activity.
- 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 does BMI stand for and how is it calculated?
BMI stands for body mass index. It's calculated by dividing your weight in kilograms by your height in metres squared (kg/m²). For example, someone weighing 70kg and 1.73m tall would have a BMI of approximately 23.4. Use our free BMI calculator on this page to work out your exact BMI in seconds.
Why do South Asian and Black African adults have lower BMI thresholds for Mounjaro?
Research shows that South Asian, Chinese, Black African, and Black Caribbean populations have a higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels compared to white European populations. The NHS acknowledges this by recommending lower BMI thresholds for these groups when assessing weight management treatment eligibility.
Can I get Mounjaro through the NHS if my BMI is between 27 and 30?
Yes, if you have weight-related health conditions like type 2 diabetes, hypertension, or obstructive sleep apnoea, you may qualify for Mounjaro even with a BMI between 27 and 29.9. Your GP will assess your individual circumstances and can refer you to a specialist weight management service for evaluation.
Is BMI the only factor that determines Mounjaro eligibility?
No. While BMI is important, your overall health, existing medical conditions, medications, and lifestyle are all considered. BMI also has limitations — it doesn't account for muscle mass or fat distribution. Your prescriber will conduct a full health assessment before deciding if Mounjaro is appropriate for you.
What's the difference between NHS and private Mounjaro prescribing?
NHS Mounjaro comes through specialist tier 3 weight management services and may have long waiting lists. Private prescribing is available through GPhC-registered online prescribers without NHS referral and is typically faster, though you'll pay for the medication. Both routes require proper clinical 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.