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
How Do I Figure Out Circumference?
Body circumference measurements are an important part of assessing your health alongside BMI, especially waist circumference which relates directly to cardiovascular risk. This UK health guide explains how to measure circumference accurately at home, why these measurements matter according to NHS guidance, and how they complement weight management tools. Accurate measurements help you track changes over time and understand your health profile more completely.
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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 to Measure Body Circumference Accurately
To measure circumference accurately, you'll need a soft measuring tape (the flexible kind used in sewing, not a rigid ruler). Wear light clothing or no clothing for the most accurate reading. Keep the tape snug against your skin but not tight enough to compress tissue. Measure in front of a mirror if possible, and take measurements on the same day and time each week for consistency.
- Waist circumference: Measure around your natural waist, midway between your hip bone and lowest rib
- Hip circumference: Measure around the fullest part of your hips and buttocks
- Chest circumference: Measure around your chest at the level of your nipples, keeping the tape parallel to the ground
- Thigh circumference: Measure around the midpoint between hip and knee
Record your measurements in centimetres or inches. Take each measurement three times and note the average. This reduces measurement error and gives you a more reliable baseline for tracking progress.
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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.
Why Waist Circumference Matters for Health
The NHS emphasises that waist circumference is an important health indicator separate from weight or BMI. Excess weight stored around the abdomen (visceral fat) poses a higher health risk than fat stored elsewhere on the body. According to NHS guidance, increased health risk begins at waist measurements of 94cm (37 inches) for men and 80cm (31.5 inches) for women. Substantially increased risk starts at 102cm (40 inches) for men and 88cm (34.5 inches) for women. Use our free BMI calculator alongside waist measurement to get a more complete picture of your health profile. Tracking both measurements helps you understand whether weight changes are improving your health markers.
- 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's the difference between circumference and waist-to-height ratio?
Waist circumference is a single measurement around your middle. Waist-to-height ratio divides your waist circumference by your height (in the same units). A healthy ratio is below 0.5 for all adults. This ratio accounts for your height, making it a more personalised health indicator than waist circumference alone.
How often should I measure my circumference?
Measure weekly or monthly, on the same day and time, wearing similar clothing. Daily measurements are not useful as natural fluid fluctuations cause small changes. Measuring monthly shows genuine progress from lifestyle changes. Record measurements consistently to track trends over time.
Can I use a regular ruler or string instead of a measuring tape?
Using string and then measuring against a ruler works, but a soft measuring tape is more accurate. Rulers can distort around curved areas. If using string, mark where it overlaps, lay it flat on a ruler, and record the distance carefully. A proper tape measure costs only a few pounds and ensures consistency.
Does circumference measurement replace BMI?
No — waist circumference and BMI give different information. BMI assesses overall weight relative to height. Waist circumference shows fat distribution and cardiovascular risk. The NHS recommends using both together. Our BMI calculator and weight converter help you assess your full health picture alongside circumference measurements.
What if my circumference is in the increased risk range?
Speak to your GP about your measurement and overall health. Increased waist circumference often responds well to weight management through diet and physical activity. Your GP can discuss whether further assessment or support is needed. Many people see improvements in circumference even with modest weight loss.
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.