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's the Minimum BMI for Mounjaro in the UK?
The minimum BMI for Mounjaro eligibility in the UK is 30 kg/m², or 27–29.9 kg/m² if you have a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds due to higher health risks at the same BMI. Your GP or a licensed prescriber will assess your individual circumstances to determine if Mounjaro is appropriate for you.
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
Standard BMI eligibility for Mounjaro:
- BMI 30 or above (obesity) — eligible for Mounjaro
- BMI 27–29.9 with weight-related health conditions — eligible for Mounjaro
- BMI below 27 without health conditions — not typically eligible
According to NHS guidelines and NICE recommendations, the healthy BMI range is 18.5 to 24.9. An overweight BMI threshold begins at 25.0, and obese categories start at 30.0. When calculating your BMI, use the formula: weight (kg) ÷ height (m)². You can check your personal BMI instantly using our free BMI calculator above.
Ethnicity-adjusted thresholds: For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds apply — you may be eligible for Mounjaro at BMI 27.5 or above, reflecting higher cardiovascular and diabetes risk at lower weight levels in these populations.
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 When to Seek Help
The NHS offers a structured approach to weight management through its tiered pathway. Tier 1 involves self-help and community programmes, while Tier 2 includes GP-led interventions. Tier 3 is where specialist weight management services assess and prescribe medications like Mounjaro, and Tier 4 covers surgical options for severe obesity.
To access Mounjaro through the NHS, you'll typically need a referral from your GP to a Tier 3 specialist service. Waiting times vary by region, and not all areas currently offer consistent access. You can also explore private prescribing through UK-licensed online clinics. Our GLP-1 weight loss calculator can help you estimate potential outcomes if you're considering Mounjaro as part of a weight management 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.
Is BMI the only factor for Mounjaro eligibility?
No. While BMI is a key screening tool, your GP or prescriber will also consider weight-related health conditions (diabetes, high blood pressure, sleep apnoea), your overall health, current medications, and whether lifestyle changes alone have been effective. BMI has limitations—it doesn't account for muscle mass or where fat is stored—so a holistic health assessment is always performed.
What if my BMI is 28 and I have type 2 diabetes?
You may be eligible for Mounjaro. The NHS criteria state that adults with a BMI of 27–29.9 with weight-related conditions (including type 2 diabetes, prediabetes, high blood pressure, or sleep apnoea) can be considered for prescription weight loss treatment. Your GP can assess whether Mounjaro is suitable for you based on your individual circumstances.
Do ethnicity-adjusted BMI thresholds apply to everyone?
Only if you identify as South Asian, Chinese, Black African, or Black Caribbean. The NHS recommends lower BMI thresholds for these populations because research shows they face higher health risks at the same BMI levels as White populations. If this applies to you, mention it to your GP—it may affect your eligibility assessment.
Can I get Mounjaro on the NHS if my BMI is below 27?
Typically not, unless you have significant weight-related health complications. NHS eligibility criteria focus on BMI 30+ or BMI 27–29.9 with documented weight-related conditions. However, individual circumstances vary, and your GP can advise on alternatives or discuss whether private prescribing might be an option for you.
How do I calculate my BMI to check my eligibility?
Use the formula: weight (kg) ÷ height (metres)². For example, if you weigh 85 kg and are 1.75 m tall: 85 ÷ (1.75)² = 27.7 BMI. Our free BMI calculator above will do this instantly for you and show you which NHS category you fall into, making it easy to understand your starting point.
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.