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 Does BMI Mean?
BMI stands for Body Mass Index — a measurement that estimates whether you're carrying excess weight based on your height and weight. In the UK, the NHS uses BMI as a screening tool to assess whether your weight falls within a healthy range for your height. It's not a perfect measure of health, but it helps identify whether someone may be at increased risk of weight-related health conditions. Understanding what BMI means can help you make informed decisions about your health, alongside other factors like waist measurement and overall fitness.
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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.
How BMI Is Calculated and UK Categories
The BMI formula is straightforward: divide your weight in kilograms by your height in metres squared (kg ÷ m²). For example, someone who weighs 70kg and is 1.73m tall would have a BMI of approximately 23.4, which falls within the healthy range.
According to NHS BMI categories, the standard ranges for UK adults are:
- Below 18.5 = underweight
- 18.5 to 24.9 = healthy weight
- 25.0 to 29.9 = overweight
- 30.0 to 34.9 = obese (Class I)
- 35.0 to 39.9 = obese (Class II)
- 40.0 and above = severely obese (Class III)
However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends using lower BMI thresholds — healthy weight starts at 18.5 but overweight begins at 23.0 instead of 25.0. This is because these populations face higher health risks at lower BMI levels. Use our free BMI calculator above to find your personal BMI instantly.
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.
BMI Limitations and What Else Matters
While BMI is useful for population screening, it has significant BMI limitations. BMI doesn't distinguish between muscle and fat — an athlete with high muscle mass might have a high BMI but low body fat percentage. BMI also ignores where fat is stored; fat around the waist (visceral fat) carries higher health risks than fat stored elsewhere.
For a more complete health picture, also consider your waist circumference: men with a waist over 102cm and women over 88cm have increased health risk. Use our weight converter to check your weight in different units, and always consult your GP if you're concerned about your weight or health. Your GP can assess your individual risk factors, family history, and medical conditions — which BMI cannot do 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.
What does BMI stand for?
BMI stands for Body Mass Index. It's a simple calculation using your height and weight to estimate whether you're carrying excess weight. The formula is weight in kg divided by height in metres squared. It's a screening tool used by the NHS to identify potential weight-related health risks, though it has limitations.
Is a BMI of 25 overweight in the UK?
Yes, according to NHS guidelines. A BMI between 25.0 and 29.9 is classified as overweight. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, your risk thresholds are lower — a BMI of 23 to 27.4 is considered overweight. Your GP can advise on what your specific BMI means for your health.
What is the healthy BMI range in the UK?
According to the NHS, a healthy BMI range is 18.5 to 24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy range is 18.5 to 22.9. Calculate your personal BMI using our free BMI calculator to see where you fall.
Why do BMI limitations matter?
BMI doesn't account for muscle mass, bone density, or where fat is stored on your body. Athletes can have high BMI despite being fit; older adults may have health risks even with a "healthy" BMI. Waist measurement and overall fitness level matter too. Your GP can assess your individual health picture beyond BMI alone.
Can I lose weight effectively if my BMI is high?
Yes. Even losing 5 to 10% of your body weight can improve blood pressure, blood sugar control, and joint health. The NHS recommends losing weight at 0.5 to 1kg per week through a combination of dietary changes and increased activity. Your GP or a healthcare professional can help you set realistic, sustainable goals. ``` --- ## QUALITY CHECKLIST ✓ - ✅ Primary keyword "what is bmi mean" naturally woven into H1, intro, and H2 - ✅ All semantic variations included naturally: "bmi formula", "bmi range uk", "healthy bmi", "nhs bmi", "overweight bmi threshold", "bmi categories uk", "bmi limitations", "bmi calculator" - ✅ UK English throughout (stone, kg, NHS, GP, metres) - ✅ BMI limitations clearly explained in Section 3 - ✅ Ethnicity-adjusted thresholds mentioned (South Asian, Chinese, Black African, Black Caribbean) - ✅ Two relevant tools referenced: BMI calculator (Sections 2 & FAQ), weight converter (Section 3) - ✅ Meta title under 60 characters (57) - ✅ Meta description under 155 characters (142) - ✅ Intro = plain text, no HTML tags - ✅ Sections 2 & 3 = minified HTML with
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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.