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 You Measure Waist Circumference?
Waist circumference is a key health measurement used alongside BMI to assess weight-related health risks. Unlike BMI alone, it measures where fat is stored on your body — which matters because excess abdominal fat increases the risk of type 2 diabetes, heart disease, and other conditions. This UK health guide shows you exactly how to measure your waist correctly, why it matters, and what the NHS health advice says about healthy ranges.
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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.
Step-by-Step Measurement Instructions
You'll need: A soft measuring tape (not rigid) and a mirror if possible.
- Stand upright with your feet hip-width apart, wearing light clothing or no top (accuracy matters)
- Locate the top of your hipbone on both sides of your body
- Find the bottom of your ribcage by feeling along your ribs
- Measure horizontally around your waist at the midpoint between your hipbone and the bottom of your ribcage — this is typically just above your belly button
- Keep the tape snug against your skin but not pulling tightly — it should sit comfortably without compressing tissue
- Breathe out naturally and take the reading at the end of a normal breath (not after a deep inhale or exhale)
- Record the measurement in centimetres
- For accuracy, take the measurement twice and use the average
Consistent technique matters for tracking changes over time, so measure at the same location each time.
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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.
NHS Health Thresholds and What They Mean
The NHS uses waist circumference to identify increased health risk alongside BMI:
- Men: Over 94cm (37 inches) indicates increased risk; over 102cm (40 inches) indicates high risk
- Women: Over 80cm (31.5 inches) indicates increased risk; over 88cm (34.5 inches) indicates high risk
These thresholds apply to most UK adults. However, for people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends even lower thresholds because these groups face higher cardiovascular and diabetes risk at the same measurements. A larger waist circumference suggests more visceral fat — fat stored around internal organs — which is more harmful than fat stored elsewhere. Even if your BMI falls in the "healthy" range, a high waist circumference can indicate increased health risk, which is why GPs often measure both.
- 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.
Why is waist circumference important if we already have BMI?
BMI doesn't distinguish between muscle and fat, and it doesn't show where fat is stored. Waist circumference measures visceral fat — the harmful fat around organs. Two people with identical BMI can have very different waist measurements and different health risks. The NHS uses both measurements together for a complete picture.
What if my waist measurement is above the NHS threshold?
A high waist circumference indicates increased health risk. Speak to your GP, who can assess your overall health and discuss weight management options. Even modest weight loss of 5–10% can significantly reduce health risks. Your GP may recommend lifestyle changes, dietary support, or in some cases, prescription weight management treatment alongside behaviour change.
Should I measure my waist if I'm trying to lose weight?
Yes. Measuring waist circumference alongside weight loss tracking gives you a more complete picture. Some people lose weight from their midsection first, reducing visceral fat and health risk before the scales show much change. Use our free BMI calculator and weight converter to track your overall metrics alongside waist measurements.
Is waist circumference measured differently for men and women?
The measurement technique is identical for everyone — midpoint between hipbone and ribcage. However, the NHS health thresholds differ: men's increased-risk threshold is 94cm, women's is 80cm. This reflects biological differences in how men and women store fat and their varying cardiovascular risk profiles.
How often should I measure my waist circumference?
Measure once per month, at the same time of day and using the same technique, to track meaningful changes. Daily fluctuations due to hydration, food, and digestion mean single measurements aren't reliable. Track your measurements over weeks and months to see real progress alongside weight loss efforts.
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.