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 a BM Test and Why It Matters in the UK
A BM test typically refers to a body measurement screening or BMI assessment — a standard UK health check used by the NHS and GPs to understand weight-related health risk. It's not a blood test, but a simple measurement-based evaluation that helps determine whether your current weight falls into a healthy range for your height. Understanding what a BM assessment involves is an important first step in managing your health, especially if you're concerned about weight-related conditions or want to track your progress towards a healthier weight. The NHS uses this information alongside other health markers to assess your overall cardiovascular and metabolic risk.
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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.
How NHS Body Measurement Screening Works in the UK
Body measurement (BM) screening in the UK is typically performed by your GP or nurse and forms part of routine health checks, particularly for adults aged 40 and over through the NHS Health Check programme. The screening involves:
- Height measurement — recorded in centimetres
- Weight measurement — recorded in kilograms or stone and pounds
- BMI calculation — weight divided by height squared, giving a number between 0 and 50+
- Waist circumference measurement — measured at the narrowest point, important for assessing abdominal fat
- Blood pressure recording — as part of wider health assessment
According to NHS guidance, a healthy BMI for most UK adults is between 18.5 and 24.9. However, for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds starting at 18.5 to 22.9 due to higher health risks at lower BMI levels. Your GP will discuss your results and any next steps needed.
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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.
UK Tools and Resources for Body Measurement Assessment
MyWeightCheck provides free health calculators designed specifically for UK adults. Our BMI calculator lets you instantly check your BMI using stone and pounds or kilograms — the measurements your GP uses. You can also use our weight converter to switch between different units, making it easy to track your measurements in whichever format suits you best.
If you're concerned about your body measurement results or want personalised guidance, your GP is always your best resource. They can explain what your measurements mean for your individual health, discuss any weight-related concerns, and recommend next steps — whether that's lifestyle changes, referral to a weight management service, or prescription support if appropriate. Many GP surgeries also offer free weight management programmes as part of NHS 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.
Is a BM test the same as a BMI test?
Not exactly. A BM test is a broader body measurement screening that includes height, weight, waist circumference, and sometimes blood pressure. BMI is just one calculation within that screening — weight divided by height squared. Your GP uses all these measurements together to assess your health risk, not just BMI alone.
What BMI range is considered healthy according to the NHS?
For most UK adults, a healthy BMI is 18.5 to 24.9. However, the NHS recommends lower thresholds for people of South Asian, Chinese, Black African, or Black Caribbean heritage — a healthy BMI for these groups starts at 18.5 to 22.9. Your GP can advise what's healthy for you personally.
Do I need to see my GP for a body measurement test?
Not necessarily. You can check your own measurements at home and use our free BMI calculator to understand where you stand. However, if you're over 40, the NHS Health Check programme offers a free assessment through your GP surgery, which includes body measurements alongside other health checks. It's worth booking one if you haven't had a check recently.
What should I do if my body measurement screening shows I'm overweight?
If your measurements fall in the overweight range, your GP can discuss what this means for your health and recommend options. This might include lifestyle changes like diet and exercise, referral to NHS weight management services, or in some cases, prescription weight management support. The good news is that even a 5–clinically studied weight loss can have significant health benefits.
Can I use a body measurement test to track weight loss progress?
Yes. Regular body measurements — including weight, waist circumference, and BMI — are excellent ways to track progress. Our free progress tracker lets you log your measurements over time, giving you a clear picture of your journey. Many people find this motivating, especially when the scales don't change but other measurements improve.
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.