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 Is the Average BMI in the UK?
The average BMI in the UK is approximately 27.5 for adults, which falls into the overweight category according to NHS guidelines. Recent data shows that around 63% of UK adults are overweight or obese (BMI 25 or above), with men averaging 27.9 and women averaging 27.4. Understanding where the average sits helps you see how your own health measures up, though individual circumstances vary significantly based on age, muscle mass, and personal health factors.
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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.
UK BMI Statistics and Healthy Ranges
The healthy BMI range according to NHS guidelines is 18.5 to 24.9. The current UK average of 27.5 shows that most adults fall above this threshold. Here's how UK BMI categories break down:
- Underweight: Below 18.5
- Healthy weight: 18.5–24.9
- Overweight: 25.0–29.9 (includes the average)
- Obese Class I: 30.0–34.9
- Obese Class II: 35.0–39.9
- Severely obese: 40.0 and above
For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — healthy weight begins at 18.5 but extends only to 22.9, reflecting higher health risks at standard BMI levels for these communities.
You can calculate your personal BMI using our free BMI calculator above to see where you fall within these ranges.
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.
BMI Limitations and What Else Matters
While average BMI statistics are useful for population health monitoring, the BMI formula has important limitations for individuals. BMI does not distinguish between muscle and fat — athletes and people with high muscle mass may have a higher BMI but lower actual body fat. Age, bone density, and where fat is stored also affect health risk independently of BMI.
The NHS recommends considering waist circumference alongside BMI: over 94cm (37 inches) in men and 80cm (31.5 inches) in women indicates increased health risk. Discuss your individual health picture with your GP, who can assess your total cardiovascular and metabolic health rather than relying on BMI alone.
- 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 an average BMI of 27.5 considered healthy?
No. The NHS defines healthy BMI as 18.5–24.9. An average BMI of 27.5 falls in the overweight category, which is above the healthy range. However, "average" doesn't mean "healthy" — it reflects that most UK adults are currently above the healthy weight threshold.
Why is the UK average BMI higher than other European countries?
Several factors contribute: higher rates of sedentary lifestyle, increased consumption of processed foods, portion sizes, and reduced physical activity. Public health campaigns and NHS weight management services aim to address this trend.
How do I know if my BMI is healthy?
Use our free BMI calculator above with your height and weight. If your result falls between 18.5 and 24.9, you're in the healthy range. For South Asian, Chinese, or Black African heritage, the range is 18.5–22.9. Your GP can also advise on your individual health context.
Does the average BMI differ between men and women?
Yes. UK men average 27.9 and women average 27.4. Both are above the healthy range, though the difference is relatively small. Individual variation within each gender is much larger than the gender difference.
What does BMI not tell me about my health?
BMI doesn't account for muscle mass, bone density, body composition, age, or where fat is stored. Two people with identical BMI can have very different health profiles. Waist circumference, fitness level, blood pressure, and cholesterol are equally important health measures.
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.