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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Understanding BMI Labels and NHS Weight Categories
BMI labels are standardised health categories used by the NHS to classify weight status in UK adults. Understanding these labels helps you know whether your weight falls within a healthy range according to NHS guidelines. Your BMI (body mass index) is calculated from your height and weight, and the resulting number falls into one of five NHS categories. Knowing your BMI label is a useful first step in assessing your health, though it's important to remember that BMI has limitations and doesn't account for muscle mass or where fat is stored on your body. Use our free BMI calculator above to find out your personal label instantly.
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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 What They Mean
The NHS recognises five standard BMI labels for UK adults. These are based on BMI ranges calculated using the formula: weight (kg) ÷ height (m)². According to NHS guidance, here are the official categories:
- Underweight: BMI below 18.5 — may indicate insufficient weight for your height
- Healthy weight: BMI 18.5 to 24.9 — the target range for most adults
- Overweight: BMI 25.0 to 29.9 — carries increased health risks
- Obese (Class I): BMI 30.0 to 34.9 — significant health concerns
- Obese (Class II): BMI 35.0 to 39.9 — substantial health risks
- Severely obese (Class III): BMI 40.0 and above — serious health concerns requiring medical support
These bmi categories uk are the standard used across NHS services. However, the NHS also recognises that for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower bmi range uk thresholds apply due to higher cardiovascular and diabetes risk at lower BMI levels.
Clinically BackedWeight Loss
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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 Support and When to Seek Help
If your BMI label indicates overweight or obesity, the NHS offers support through its structured weight management pathway. Tier 1 includes self-help resources and community programmes. Tier 2 offers primary care support from your GP, including behaviour change programmes like the NHS Weight Loss Plan. Tier 3 provides specialist multidisciplinary weight management services, where prescription medications may be prescribed. Your GP can assess which tier suits you and refer you appropriately. Even modest weight loss of 5–10% can improve blood pressure, blood sugar control, and reduce cardiovascular risk. The NHS recommends sustainable weight loss of 0.5–1 kg per week alongside dietary changes and increased physical activity. Use our weight converter to track your progress in stone and kg.
- 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 label means I'm at a healthy weight according to the NHS?
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. This range suggests your weight is appropriate for your height and carries the lowest health risks. However, BMI is just one indicator — your GP may also consider waist circumference, fitness level, and overall health. Use our BMI calculator to check your personal label.
Are BMI labels the same for all adults in the UK?
No. The NHS recognises that adults of South Asian, Chinese, Black African, and Black Caribbean heritage have higher cardiovascular and diabetes risk at lower BMI levels. For these groups, the overweight threshold starts at BMI 23 (instead of 25) and obesity at BMI 27.5 (instead of 30). Your GP can advise on thresholds relevant to you.
What should I do if my BMI label shows I'm overweight?
Start by speaking to your GP, who can assess your overall health and discuss options. The NHS recommends losing weight gradually at 0.5–1 kg per week through balanced eating and increased activity. Your GP may refer you to tier 2 or tier 3 weight management services depending on your health needs and local availability.
Does BMI label account for muscle mass?
No, this is a key limitation of BMI labels. BMI cannot distinguish between muscle and fat — athletes may have a high BMI but low body fat. If you're very muscular, your GP may use additional measurements like waist circumference to assess health more accurately.
Can I access NHS weight loss medication if my BMI label is "overweight" rather than "obese"?
Possibly. Prescription weight loss medications are available on the NHS for adults with BMI 27 or above (or 25 or above with weight-related health conditions like high blood pressure or type 2 diabetes). You'll need assessment by a specialist weight management service, typically via referral from your GP. Availability varies by region.
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.