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 Are the BMI Requirements for Wegovy in the UK?
Wegovy (semaglutide) is a prescription-only weight management injection available in the UK. To be eligible, you must meet specific BMI thresholds set out in NHS guidance. In most cases, you need a BMI of 30 or above, or a BMI of 27–29.9 if you have weight-related health conditions. If you're from a South Asian, Chinese, Black African, or Black Caribbean background, lower BMI thresholds may apply. Your GP or a licensed prescriber will assess your individual circumstances before offering this medication.
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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 Eligibility Thresholds
The NHS BMI categories form the foundation for Wegovy eligibility decisions. A healthy BMI according to NHS guidance is between 18.5 and 24.9; overweight is 25.0–29.9; and obese is 30.0 and above. For general eligibility, you typically qualify for Wegovy if your BMI is 30 or above (obese category).
However, you may also be eligible with a lower BMI of 27–29.9 (overweight category) if you have at least one weight-related health condition. These include type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol levels, obstructive sleep apnoea, or a history of heart attack or stroke.
For people of South Asian, Chinese, Black African, and Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher cardiovascular and metabolic risks at lower weights. Your prescriber will apply these adjusted thresholds if relevant to you. Use our free BMI calculator above to find your current BMI instantly and compare it against NHS guidelines.
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.
The NHS Weight Management Pathway
In the UK, prescription weight loss treatment like Wegovy sits within a structured NHS weight management pathway. This typically starts with tier 1 self-help support and NHS resources, escalating through tiers 2 and 3 (specialist services) where medications may be prescribed. Access through the NHS requires referral to a specialist tier 3 weight management service from your GP, though availability and waiting times vary significantly by region.
Alternatively, you can access Wegovy privately through a GPhC-registered online pharmacy following an assessment with a UK-licensed prescriber — this does not require NHS referral. Either way, a prescriber will evaluate your BMI, medical history, and health conditions before prescribing. Losing weight alongside increased physical activity and dietary changes produces the best outcomes. Track your progress over time using our free progress tracker.
- 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 qualify for Wegovy on the NHS?
You typically need a BMI of 30 or above, or 27–29.9 if you have weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply. Your GP can assess your individual eligibility.
How do I calculate my BMI to check if I meet Wegovy requirements?
BMI is calculated using the bmi formula: weight in kilograms divided by height in metres squared. For example, a person weighing 85kg and 1.75m tall has a BMI of about 27.8. Use our free BMI calculator above to instantly find your BMI and see how it compares to NHS categories.
Are BMI requirements the same for everyone in the UK?
No. The NHS applies lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean backgrounds due to higher health risks at lower weights in these groups. Your prescriber will use the appropriate thresholds for your ethnicity.
What are the main limitations of using BMI to assess weight?
BMI does not distinguish muscle from fat, so athletes may have a high BMI despite low body fat. BMI also ignores where fat is stored and does not account for age-related muscle loss. The NHS recommends using BMI alongside waist measurement and other health markers for a complete picture.
Can I get Wegovy through the NHS or do I have to go private?
Both options exist in the UK. NHS access is through specialist tier 3 weight management services (typically via GP referral), though waiting times are often very long and availability varies by region. Private prescribing through online GPhC-registered pharmacies is available without NHS referral but costs around £130–£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.