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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NHS BMI Graph — Understanding UK Weight Categories
The NHS BMI graph shows the standard weight categories used by healthcare professionals across the UK. Your BMI (body mass index) is calculated from your height and weight, and the NHS uses specific thresholds to determine whether you're in a healthy weight range. Understanding where you fall on the BMI scale helps you assess your health risk and decide if you need support from your GP. Use our free BMI calculator above to find your personal BMI instantly and see which NHS category you fall into.
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 Healthy Weight Ranges
The NHS BMI formula divides your weight in kilograms by your height in metres squared. The NHS uses these standard BMI categories UK for adults:
- Underweight: BMI below 18.5 — may indicate you need more nutritional support
- Healthy weight: BMI 18.5 to 24.9 — the healthy BMI range recommended by NHS guidelines
- Overweight: BMI 25.0 to 29.9 — increased health risk begins here
- Obese (Class I): BMI 30.0 to 34.9 — significant health risks
- Obese (Class II): BMI 35.0 to 39.9 — higher health risks
- Severely obese (Class III): BMI 40.0 and above — serious health concerns
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the overweight BMI threshold is lower — the nhs bmi recommendations suggest a healthy range of 18.5 to 22.9, with overweight starting at 23.0. This reflects higher cardiovascular and diabetes risk in these populations 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 Support and Next Steps
If your BMI falls outside the healthy range, the NHS offers a structured weight management pathway. Your GP can assess your health and refer you to tier 1 community programmes, tier 2 primary care services, or tier 3 specialist weight management teams depending on your needs. The NHS recommends sustainable weight loss of around 0.5 to 1 kg per week. For people with a BMI of 30 or above, or 27 to 29.9 with weight-related conditions like type 2 diabetes or high blood pressure, prescription support may be available. Speak with your GP about what support is right for you — they can also refer you to dietitians, exercise specialists, and behavioural support services.
- 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 NHS healthy BMI range for UK adults?
The NHS defines a healthy BMI as 18.5 to 24.9 for most adults. For South Asian, Chinese, Black African, and Black Caribbean adults, the healthy range is 18.5 to 22.9. Your GP can discuss whether your personal BMI is healthy for your individual circumstances.
Why are BMI thresholds different for some ethnic groups?
Research shows that people from South Asian, Chinese, Black African, and Black Caribbean backgrounds have higher risks of type 2 diabetes and heart disease at lower BMI levels. The NHS adjusted thresholds reflect this increased health risk and allow earlier intervention.
Does the NHS BMI graph account for muscle mass?
No — this is a key BMI limitation. BMI does not distinguish between muscle and fat, so athletes and very muscular individuals may have a high BMI without excess body fat. Your GP can assess your overall health risk using other measures like waist circumference.
How can I reduce my BMI according to NHS guidance?
The NHS recommends a calorie deficit of around 500 kcal per day for gradual, sustainable weight loss. This involves eating a balanced diet, reducing portion sizes, and increasing physical activity. Your GP or a dietitian can provide personalised guidance for your situation.
When should I contact my GP about my BMI?
If your BMI is outside the healthy range, or if you have a BMI between 25 and 29.9 with weight-related health conditions, speak to your GP. They can assess your health risk, discuss lifestyle changes, and refer you to NHS weight management services if appropriate.
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.