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 among UK adults is approximately 27.4 for women and 27.9 for men, according to Office for National Statistics data. This means the average UK adult is classified as overweight according to NHS guidelines, which define a healthy BMI as falling between 18.5 and 24.9. However, individual BMI varies significantly across age groups, regions, and ethnic backgrounds. Understanding where your own BMI sits within the NHS BMI range is the first step towards assessing your personal health. You can calculate your BMI instantly using our free BMI calculator above to see how you compare.
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 What They Mean
The NHS BMI categories are the standard health framework used across the UK. According to NICE guidance, these are the official classifications:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obese (Class I): BMI 30.0 to 34.9
- Obese (Class II): BMI 35.0 to 39.9
- Severely obese (Class III): BMI 40.0 and above
Because the average UK adult has a BMI around 27–28, most of the population falls into the overweight category. However, BMI limitations exist — it does not distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. The bmi formula (weight in kg ÷ height in metres²) is the same for everyone, but what matters is how your individual BMI relates to your health risks. Use the free weight converter on this page to check your weight in different units, then calculate your personal BMI.
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.
NHS Weight Management Support and When to Seek Help
The NHS offers a tiered approach to weight management. If your BMI is above the healthy range, your GP can refer you to NHS support services. NHS guidelines recommend that adults with a BMI of 30 or above, or 25–29.9 with weight-related health conditions, should seek professional support. The NHS weight management pathway includes Tier 1 (self-help and digital tools like MyWeightCheck), Tier 2 (primary care programmes), Tier 3 (specialist services), and Tier 4 (bariatric surgery for severe obesity).
Even a modest 5–10% reduction in body weight can significantly improve health outcomes including blood pressure, blood sugar control, and cardiovascular risk. Your GP can discuss your individual BMI context and recommend appropriate next steps based on your health, medications, and personal circumstances.
- 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 a BMI of 27 considered overweight in the UK?
Yes. According to NHS guidelines, a BMI of 27 falls in the overweight category (BMI 25.0–29.9). However, this does not mean you are unhealthy — BMI is a screening tool only. Your GP can assess your individual health risk based on other factors including waist circumference, blood pressure, and medical history.
What is the healthy BMI range according to the NHS?
The NHS defines a healthy BMI as 18.5 to 24.9 for most adults. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a slightly lower healthy range of 18.5 to 22.9, as these groups face higher health risks at lower BMI levels.
Why is the average UK BMI higher than the healthy range?
Multiple factors contribute: sedentary lifestyles, increased calorie availability, stress, sleep disruption, and medical conditions. Public Health England data shows that around 63% of UK adults are overweight or obese. This reflects population-wide changes in diet and activity patterns, not individual failure.
How do I know if my BMI puts me at health risk?
Use our free BMI calculator above to find your personal BMI. If it's above 25, discuss it with your GP. They will consider your BMI alongside waist circumference (for men >102cm and women >88cm indicates increased risk), blood pressure, and medical history to assess your actual health risk.
What should I do if my BMI is in the obese category?
Contact your GP. They can refer you to NHS weight management services (Tier 2 or 3), which may include dietary advice, behaviour change support, or in some cases, prescription weight management medication. The NHS offers evidence-based support tailored to your individual needs 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.