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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BMI for Wegovy: NHS Eligibility and Weight Categories
If you're considering Wegovy for weight management, understanding your BMI is the first step. BMI (body mass index) is how the NHS assesses whether prescription weight loss treatment like Wegovy may be suitable for you. This guide explains NHS BMI categories, eligibility thresholds for Wegovy, and how to work out whether you might qualify. Use our free BMI calculator above to find your personal BMI instantly — then read on to understand what it means in the context of NHS weight management guidance.
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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 Categories and Wegovy Eligibility Thresholds
The NHS uses standardised BMI categories to assess weight and health risk. These categories apply to most UK adults:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese (Class I): BMI 30.0–34.9
- Obese (Class II): BMI 35.0–39.9
- Severely obese: BMI 40.0 and above
For Wegovy eligibility in the UK, adults typically need a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or cardiovascular disease). However, lower BMI thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage — eligibility may start at BMI 27.5 or above for these groups, reflecting their higher health risk at lower BMI levels.
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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 How to Access Wegovy
The NHS offers a four-tier weight management pathway. Tier 1 covers self-help and community programmes; Tier 2 involves primary care support; Tier 3 is specialist multidisciplinary services where prescription medications like Wegovy are typically initiated; Tier 4 covers bariatric surgery for severe obesity.
If you think you may qualify for Wegovy based on your BMI and health conditions, speak to your GP. They can assess your eligibility and refer you to a specialist tier 3 weight management service in your area. Be aware that NHS waiting times vary significantly by region — some areas have lengthy lists. Alternatively, Wegovy is available privately through GPhC-registered online prescribers following a clinical assessment, though this involves a cost. Try our GLP-1 weight loss calculator to understand potential outcomes, and use the weight converter to track changes in both kg and stone.
- 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 BMI do I need to be eligible for Wegovy on the NHS?
You typically need a BMI of 30 or above, or BMI 27–29.9 with a weight-related condition like type 2 diabetes or high blood pressure. Lower thresholds (from BMI 27.5) apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Your GP can assess your individual eligibility.
How do I calculate my BMI for Wegovy eligibility?
BMI is calculated as weight (kg) divided by height (metres) squared. For example, if you weigh 85kg and are 1.75m tall, your BMI is 85 ÷ (1.75 × 1.75) = 27.7. Use our free BMI calculator above to find your exact BMI instantly.
Does BMI tell the whole story about weight and health?
No. BMI doesn't distinguish between muscle and fat, and it doesn't account for where fat is stored. Waist circumference is also important — the NHS recommends measuring waist as part of health assessment. Your GP can give you personalised health context beyond BMI alone.
Can I get Wegovy through the NHS?
Yes, Wegovy is available through NHS specialist tier 3 weight management services if you meet BMI and health criteria. However, availability and waiting times vary significantly by region. Your GP can refer you, or you can access Wegovy privately through an online prescriber if you prefer quicker access.
What's the difference between Wegovy and other weight loss injections?
Wegovy (semaglutide) is a GLP-1 injection; Mounjaro (tirzepatide) is a dual GIP/GLP-1 injection. Both require similar BMI eligibility, but they work slightly differently. Your prescriber will assess which is most suitable for you based on your health and circumstances.
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.