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 UK adults is approximately 27.4 for women and 27.9 for men — both falling into the overweight category according to NHS guidelines. However, average doesn't mean healthy. The NHS recommends a healthy BMI range of 18.5 to 24.9 for most adults, and lower thresholds for people of South Asian, Chinese, Black African, or Black Caribbean heritage. Understanding where your BMI sits within the official NHS BMI range and categories is the first step toward making informed health decisions. Use our free BMI calculator above to check your personal BMI instantly.
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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.
NHS BMI Categories and What They Mean
The NHS BMI categories are the official UK standard for assessing healthy weight. Here's how BMI ranges break down:
- Underweight: BMI below 18.5 — may need nutritional support
- Healthy weight: BMI 18.5–24.9 — associated with lower health risks
- Overweight: BMI 25.0–29.9 — increased risk of weight-related health conditions
- Obese (Class I): BMI 30.0–34.9 — significant health risks
- Obese (Class II): BMI 35.0–39.9 — higher health risks
- Severely obese (Class III): BMI 40.0+ — very high health risks
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower overweight BMI threshold starting at 23.0 and obesity at 27.5 — because these groups face higher cardiovascular and diabetes risk at lower BMI levels. NICE guidance supports these ethnicity-adjusted thresholds. The BMI formula used is weight (kg) divided by height (m) squared.
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
If your BMI falls outside the healthy range, the NHS offers structured support through its weight management pathway. Your GP can assess your individual health and discuss options at each tier: tier 1 includes self-help tools and digital programmes; tier 2 involves primary care-based behaviour change support; tier 3 offers specialist multidisciplinary weight management services where prescription medications may be considered; tier 4 covers bariatric surgery for severe obesity with significant health complications.
Even modest weight loss of 5–10% of your body weight can meaningfully improve blood pressure, blood sugar control, and reduce joint pain. Contact your GP if you'd like personalised advice about your healthy weight range, or use our weight converter and BMI calculator on this page to understand your current position within NHS guidelines.
- 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 considered a healthy BMI in the UK according to NHS guidelines?
According to NHS standards, a healthy BMI for most UK adults is between 18.5 and 24.9. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the recommended healthy range is 18.5 to 22.9 due to higher health risks at higher BMI levels in these populations.
Why is the UK average BMI above the healthy range?
The average BMI in the UK (approximately 27.4–27.9) is above the NHS healthy range due to multiple factors: sedentary lifestyles, increased availability of calorie-dense foods, stress, and socioeconomic factors. This reflects broader patterns across developed countries.
What BMI limitations should I be aware of?
BMI limitations include that it doesn't distinguish between muscle and fat (athletes may have high BMI but low body fat), doesn't account for fat distribution (where fat is stored matters for health), and may be less accurate in elderly people or during pregnancy. Waist circumference is also important.
What should I do if my BMI is above the healthy range?
Start by booking an appointment with your GP to discuss your individual health context. The NHS offers a structured weight management pathway starting with self-help tools and digital support, progressing to specialist services if needed. Even small lifestyle changes can improve health outcomes.
How does ethnicity affect BMI categories?
The NHS recognises that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher risk of type 2 diabetes and heart disease at lower BMI levels. Therefore, lower BMI thresholds apply: overweight starts at 23.0 and obesity at 27.5 instead of 25.0 and 30.0.
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.