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
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How to Measure Your Waist Size Correctly
Measuring your waist size accurately is an important part of understanding your health risk. Unlike BMI, which doesn't account for where fat is stored, waist circumference is a direct indicator of abdominal fat — the type most linked to cardiovascular disease and type 2 diabetes. The NHS recommends waist measurement alongside BMI for a complete health picture. This UK health guide shows you the correct technique and explains why this measurement matters for your wellbeing.
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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 Waist Measurement Technique
Find the right position: Stand upright with your feet together and your abdomen relaxed (not pulled in). You should be wearing minimal clothing, or thin clothing only — heavy layers will give an inaccurate reading.
Locate the measurement point: Place your fingers on your hip bones (the top of your pelvis). Measure horizontally around your body at the point midway between your hip bone and the lowest rib. This is typically just above your belly button, though the exact spot varies slightly between individuals.
Take the measurement: Wrap a soft measuring tape (cloth tape works best) around your waist horizontally, keeping it snug but not tight. The tape should be parallel to the floor. Take the reading at the end of a normal breath — not whilst holding your breath in or letting your stomach relax completely. Record your measurement to the nearest 0.5 cm.
Check your reading: Take the measurement twice and average the two results. This ensures accuracy and accounts for minor variation.
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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.
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What Your Waist Measurement Means
NHS health risk guidance: For men, a waist circumference over 94 cm (37 inches) indicates increased health risk, and over 102 cm (40 inches) indicates high risk. For women, the thresholds are 80 cm (31.5 inches) for increased risk and 88 cm (34.5 inches) for high risk. These levels are associated with increased risk of type 2 diabetes, cardiovascular disease, and certain cancers.
Waist measurement is particularly important because it reflects visceral fat — fat stored around your organs — which is more metabolically active and harmful than fat stored elsewhere. You can use our free BMI calculator alongside your waist measurement to get a complete picture of your health risk.
If your waist circumference is above the healthy range, speak to your GP about weight management support, which may include lifestyle changes or, in some cases, prescription weight loss medication following a clinical assessment.
- 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 waist size and BMI?
BMI measures overall weight relative to height but doesn't distinguish between muscle and fat, or where fat is stored. Waist circumference measures abdominal fat specifically — the type most linked to heart disease and diabetes. The NHS recommends using both measurements together for a complete health assessment.
Should I measure my waist over clothes or on bare skin?
Measure on bare skin or over thin clothing only. Thick clothing, belts, or layers will give inaccurate results. The tape should sit comfortably against your skin without compressing it or leaving marks.
What if my waist measurement is above the NHS healthy range?
A high waist circumference indicates increased health risk and warrants a conversation with your GP. Even modest weight loss of 5–10% of your body weight can improve health markers. Your GP can discuss lifestyle changes, dietary support, or other options appropriate for your individual situation.
Is waist measurement accurate for everyone, including people with disabilities or pregnancy?
Waist measurement is challenging for pregnant women — guidelines suggest measurement before pregnancy or after delivery. For individuals with mobility issues or disabilities affecting measurement, discuss alternative assessment methods with your GP, who may use other health indicators.
How often should I measure my waist?
The NHS suggests measuring waist circumference alongside BMI at regular health checks — typically annually or when monitoring weight changes. If you're actively managing your weight, monthly measurements can help track progress, though weight can fluctuate daily due to water retention and other factors.
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.