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 to Size Your Waist — A UK Health Guide
Measuring your waist correctly is an important part of assessing your health, especially in the UK where NHS guidance emphasises waist circumference alongside BMI. Your waist measurement can indicate how much fat you're carrying around your organs, which is linked to serious health conditions like type 2 diabetes and heart disease. This guide walks you through the correct technique, explains healthy waist measurements for UK adults, and shows how waist size fits into your overall weight management picture.
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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 to Measure Your Waist — The Correct Method
Measuring your waist accurately requires a soft measuring tape and a mirror. Stand upright with feet shoulder-width apart, relax your stomach (don't suck in or push out), and locate the natural crease above your hip bone and below your rib cage — this is where your waist measurement should be taken. Wrap the measuring tape around this point, keeping it parallel to the ground and snug but not tight. The tape should sit directly against your skin, not over clothing. Read the measurement where the tape overlaps and note it in centimetres or inches. For accuracy, take the measurement three times and use the average. Measure at the same time of day, ideally in the morning before eating, as waist measurements can fluctuate by up to 2cm depending on meals and hydration. This consistent approach aligns with NHS health monitoring guidance and helps you track genuine changes over time rather than daily variations.
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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.
Healthy Waist Measurements — NHS Guidelines
According to NHS guidance, healthy waist circumference limits for UK adults are:
- Men: below 94cm (37 inches)
- Women: below 80cm (31.5 inches)
If your waist measurement exceeds these thresholds, you have an increased risk of weight-related health conditions. Above 102cm for men or 88cm for women indicates high risk. Waist measurement is important because it reflects visceral fat — fat stored around organs — which is more harmful to health than fat stored elsewhere on your body. Use our free BMI calculator above alongside your waist measurement for a complete picture of your health. For South Asian, Chinese, or Black African and Caribbean adults, slightly lower thresholds apply due to higher metabolic risk at the same measurements.
- 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 waist circumference?
Waist size typically refers to clothing sizes (measured in inches or cm), while waist circumference is the health measurement around your natural waist for health risk assessment. For health purposes, use the natural waist crease method described above, not clothing measurements.
Why does the NHS focus on waist measurement if I already know my BMI?
Waist circumference reveals where your body stores fat. BMI doesn't distinguish between muscle and fat, or show fat distribution. Someone with a healthy BMI but high waist measurement may still face increased health risks. Both measurements together give a fuller health picture aligned with NHS guidance.
Should I measure my waist daily to track weight loss?
Waist measurements fluctuate daily based on meals, water intake, hormones, and digestion. Weekly or monthly measurements are more meaningful. If you're tracking progress, use our free progress tracker on this site for consistent logging and easier trend spotting over weeks.
What should I do if my waist measurement is above the healthy range?
Speak with your GP. They can assess your overall health, discuss weight management options, and refer you to specialist services if needed. Even a 5% reduction in waist circumference can significantly improve health markers. Your GP can advise whether structured weight management support is appropriate for you.
Can men and women measure their waist the same way?
Yes — the technique is identical. However, the healthy thresholds differ: men below 94cm, women below 80cm. These reflect different metabolic and cardiovascular risk profiles. Both measurements should use the same natural waist crease method for consistency.
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.