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
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What BMI Do You Need to Qualify for Mounjaro in the UK?
If you're considering Mounjaro for weight management in the UK, your BMI is a key factor in eligibility assessment. The NHS and private prescribers use specific BMI thresholds to determine who may benefit from this prescription-only injection. Understanding these thresholds and how the NHS BMI categories work will help you know where you stand and what your next steps might be. Let's break down the exact eligibility criteria and what the NHS recommends.
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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 Thresholds and Eligibility for Mounjaro
Adults with a BMI of 30 kg/m² or above qualify for consideration for Mounjaro in the UK. If your BMI falls between 27 and 29.9 kg/m², you may still be eligible if you have at least one weight-related health condition — such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or cardiovascular disease history.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds due to higher health risks at lower BMI levels. In these groups, eligibility may start at a BMI of 27.5 or above, or even 23 if weight-related conditions are present.
To find your personal BMI, use our free BMI calculator above — this gives you an gradual improvement based on your height and weight. According to the NHS BMI range, a healthy BMI sits between 18.5 and 24.9 kg/m². The overweight BMI threshold begins at 25, and obesity (where Mounjaro eligibility typically begins) starts at 30.
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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 Getting Mounjaro
Access to Mounjaro through the NHS happens via specialist tier 3 and tier 4 weight management services, not through routine GP prescribing. Your GP can refer you to these specialist services, but availability and waiting times vary significantly by region and integrated care board (ICB). In some areas, NHS Mounjaro access is limited or has extended waiting lists.
If NHS access isn't immediately available, Mounjaro is also available privately through UK-licensed prescribers following an online clinical assessment. A prescriber will review your BMI, health history, and suitability before issuing a prescription. Whichever route you take, remember that Mounjaro works best alongside a reduced-calorie diet and increased physical activity. Track your progress using our free progress tracker as you work towards your health goals.
- 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 the exact BMI to qualify for Mounjaro on the NHS?
A BMI of 30 kg/m² or above generally qualifies. If your BMI is 27–29.9 kg/m² with a weight-related condition (diabetes, high blood pressure, heart disease), you may also qualify. For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply — starting around 27.5 or 23 with comorbidities.
How do I calculate my BMI to check if I qualify?
Use the BMI formula: weight (kg) ÷ height (m)². Or use our free BMI calculator on this page for an gradual improvement. For example, someone who is 75kg and 1.73m tall has a BMI of approximately 25.1. You can also use our weight converter to switch between stone, pounds, and kilograms.
Can I get Mounjaro on the NHS if my BMI is below 30?
Yes, if your BMI is 27–29.9 kg/m² and you have a weight-related health condition, you may qualify. Conditions include type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol, sleep apnoea, or cardiovascular disease. Your GP or specialist will assess your individual situation.
What happens after I'm referred to an NHS weight management service?
The specialist service will conduct a full assessment, which may include blood tests, health history review, and discussion of lifestyle changes. If Mounjaro is deemed appropriate, they'll explain how it works, discuss potential side effects, and provide ongoing monitoring. Waiting times vary by region.
What if the NHS waiting list is too long?
Private prescribing is available through GPhC-registered online pharmacies. You'll need an online clinical assessment with a UK-licensed prescriber, who'll review your BMI, health history, and suitability before issuing a prescription. Private costs vary but are typically £129–£320 per month depending on dose.
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.