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
Where to Measure Your Waist for Accurate Health Assessment
Measuring your waist correctly is essential for assessing health risk, as waist circumference is a key indicator alongside BMI. Unlike height and weight alone, waist measurement reflects where fat is stored — which matters for cardiovascular and metabolic health. The NHS recognises that even people with a healthy BMI can face increased health risks if excess fat is concentrated around the abdomen. This guide shows you exactly where and how to measure, plus what the NHS considers healthy thresholds for UK adults.
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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 Your Waist Correctly
The correct measurement point is at the midpoint between your lowest rib and the top of your hip bone (iliac crest). This is not at your natural waistline (where you wear trousers) — it's slightly higher. Stand relaxed in front of a mirror, breathe normally (do not hold your breath), and wrap a soft measuring tape horizontally around this midpoint. The tape should be snug but not tight — you should be able to slide one finger under it comfortably.
- Use a flexible tape measure, not a rigid ruler
- Measure over bare skin if possible, or thin clothing only
- Keep the tape parallel to the ground
- Take the measurement at the end of a normal breath out
- Record to the nearest 0.5 cm (or 0.25 inches)
Consistency matters. Measure at the same time of day, in the same conditions, to track changes accurately. Many people find measuring first thing in the morning gives the most consistent results.
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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 Healthy Waist Thresholds for UK Adults
The NHS provides clear waist circumference thresholds that indicate increased health risk:
- Men: over 94 cm (37 inches) = increased risk; over 102 cm (40 inches) = high risk
- Women: over 80 cm (31.5 inches) = increased risk; over 88 cm (34.5 inches) = high risk
These thresholds are particularly important for people of South Asian, Chinese, Black African, or Black Caribbean heritage, who face higher metabolic risk at lower waist measurements. Waist measurement is valuable because it reflects visceral fat — the fat stored around organs — which is metabolically more active and carries greater health risk than fat stored elsewhere. Even if your BMI is healthy, a large waist circumference suggests increased cardiovascular and diabetes risk. Use our free BMI calculator alongside waist measurement for a complete health picture.
- 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 measurement important if I already know my BMI?
BMI does not distinguish between muscle and fat, and does not show where fat is stored. Waist circumference measures visceral fat around organs, which increases metabolic risk independent of BMI. Someone with a healthy BMI but large waist circumference may still face increased health risk. This is why the NHS recommends both measurements.
Can I measure my waist while wearing clothes?
Ideally, measure over bare skin for accuracy. If you must wear clothes, use thin fabric only and remember to subtract the thickness when logging your measurement. Measuring over thick jumpers or multiple layers will give inaccurate results.
Should I measure my waist every day?
Once or twice weekly is sufficient. Waist circumference naturally fluctuates day-to-day based on hydration, food intake, and hormones, so daily measurement is not necessary and can be discouraging. Weekly measurement shows the true trend better.
What if my waist measurement is over the NHS threshold?
Speak to your GP about strategies to reduce waist circumference. Even a modest reduction — 5–10 cm — can significantly reduce health risk. Your GP can discuss lifestyle changes, weight management options, or referral to specialist weight management services. Use our GLP-1 weight loss calculator to understand what might be achievable with evidence-based support.
Is waist-to-height ratio better than waist measurement alone?
Waist-to-height ratio (waist circumference ÷ height, in the same units) is a useful screening tool — a healthy ratio is below 0.5. It accounts for height, so shorter people have different absolute waist measurements but similar health risk at the same ratio. Both measurements are valuable; your GP can advise which is most relevant for you.
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.