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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What's a Healthy Waist Size in the UK?
Your waist size is an important health marker that your GP may discuss with you. In the UK, NHS guidance recommends healthy waist measurements based on sex and ethnicity, as where you carry weight matters for your health. Unlike BMI, which measures overall weight relative to height, waist circumference directly indicates abdominal fat—a stronger predictor of heart disease, type 2 diabetes, and other health conditions. This uk health guide explains what measurements mean and why your GP tracks this alongside other health indicators.
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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.
NHS Waist Circumference Guidance
The NHS recommends these healthy waist measurements for UK adults:
- Men: Under 94cm (37 inches) is healthy; 94–102cm (37–40 inches) indicates increased health risk; over 102cm (40 inches) indicates high health risk
- Women: Under 80cm (31.5 inches) is healthy; 80–88cm (31.5–34.5 inches) indicates increased risk; over 88cm (34.5 inches) indicates high risk
- South Asian, Chinese, Black African, and Black Caribbean adults: NHS thresholds are lower due to higher cardiovascular risk at the same measurements—discuss with your GP for personalised guidance
These measurements are more predictive of metabolic health than BMI alone. Excess abdominal fat increases insulin resistance and inflammation, raising risk of type 2 diabetes, high blood pressure, and heart disease—even in people with a healthy BMI. Your GP may measure waist circumference during routine health checks.
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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.
How to Measure Your Waist Correctly
To get an accurate measurement at home: Stand upright, relax your abdomen (do not suck in), and measure around your waist at the midpoint between your lowest rib and hip bone, using a soft measuring tape parallel to the ground. Take the measurement at the end of a normal breath out. Measure twice to confirm accuracy.
Record your measurement in centimetres for NHS guidance context. If your waist size falls in the increased or high-risk range, discuss this with your GP. Weight management combining reduced-calorie diet and increased physical activity can help reduce waist circumference—often with benefits visible before significant weight loss on the scales. Use our free BMI calculator alongside waist measurement for a fuller picture of your health.
- 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 size important if my BMI is healthy?
BMI does not distinguish between muscle and fat, or where fat is stored. Abdominal fat (visceral fat) is metabolically active and raises disease risk more than fat stored elsewhere. You can have a healthy BMI but carry excess abdominal fat, increasing risk of type 2 diabetes and heart disease. This is why NHS guidance recommends measuring waist circumference alongside BMI for a complete health picture.
What's the difference between waist size and waist-to-height ratio?
Waist size alone tells you abdominal fat level. Waist-to-height ratio (waist circumference ÷ height in the same units) accounts for your frame size. A healthy ratio is below 0.5 for all adults. For example, someone 170cm tall should aim for a waist under 85cm. Both measurements are useful; your GP can advise which is most relevant for you.
Can I reduce my waist size without losing overall weight?
Yes, to some degree. Reduced-calorie diet and exercise—especially aerobic activity and strength training—can reduce visceral abdominal fat preferentially, sometimes shrinking waist size noticeably before significant weight loss on scales. However, sustained waist reduction typically requires a modest overall calorie deficit of around 500 kcal per day, resulting in approximately 0.5kg per week weight loss alongside dietary and exercise changes.
Are waist measurements different for men and women?
Yes. The NHS recommends lower thresholds for women (under 80cm healthy) than men (under 94cm healthy) because women naturally have different fat distribution patterns. However, the health risk from excess abdominal fat applies to both sexes. Additionally, some ethnic groups have different thresholds—your GP can advise your personal healthy range.
Should I use my waist size to diagnose health conditions?
No—waist measurement is a screening tool, not a diagnosis. If your waist size is in the increased or high-risk range, discuss this with your GP. They can assess your overall health, other risk factors, blood pressure, blood sugar, and cholesterol to give you personalised nhs health advice and discuss whether weight management or other interventions would benefit you.
Ready to take control of your weight loss journey?
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