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
What Is a Healthy Waist Size in the UK?
Waist circumference is one of the most important health measurements you can track—sometimes even more revealing than overall weight. The NHS recommends specific healthy waist size thresholds based on sex, and measuring your waist can help identify health risks that a BMI reading alone might miss. This guide explains healthy waist sizes in the UK, why they matter, and how to measure correctly.
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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 Healthy Waist Size Guidelines
The NHS recommends these waist circumference thresholds for UK adults:
- Men: Below 94 cm (37 inches) = low risk; 94–102 cm (37–40 inches) = increased risk; above 102 cm (40 inches) = high health risk
- Women: Below 80 cm (31.5 inches) = low risk; 80–88 cm (31.5–34.5 inches) = increased risk; above 88 cm (34.5 inches) = high health risk
These thresholds apply to adults of European descent. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds—typically starting increased risk at 90 cm for men and 80 cm for women—because these groups face higher cardiovascular and type 2 diabetes risk at lower waist measurements. Excess weight around the middle (abdominal fat) is particularly harmful because it surrounds vital organs and is metabolically active, increasing inflammation and disease risk.
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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.
Why Waist Size Matters More Than Weight Alone
Where your body stores fat matters. Two people of the same weight and BMI can have very different health risks depending on waist circumference. Central obesity—carrying excess weight around the stomach—is more strongly linked to type 2 diabetes, heart disease, and metabolic syndrome than overall body weight. Using our free BMI calculator alongside waist measurement gives a much clearer health picture than either measure alone. The NHS now emphasises waist measurement as a key part of health assessment because it's simple, quick, and highly predictive of health outcomes. Even if your BMI is in the healthy range, a high waist circumference can indicate health risk.
- 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.
How do I measure my waist correctly?
Stand relaxed and upright. Locate the midpoint between your lowest rib and the top of your hip bone. Wrap a soft tape measure around this point horizontally, keeping it snug but not tight. Take the measurement to the nearest centimetre. Measure at the end of a normal breath out. Avoid pulling the tape tight or holding your stomach in—accurate measurement is more important than a flattering result.
Can I have a healthy BMI but an unhealthy waist size?
Yes, absolutely. BMI doesn't distinguish between muscle and fat or show where fat is stored. You could have a healthy BMI but high central obesity, which increases disease risk. This is why the NHS recommends measuring both—they give different information. Use our free weight converter to compare your weight in different units, then check both your BMI and waist measurement for a complete picture.
Does waist size matter if I'm losing weight?
Yes. Waist circumference often decreases before overall body weight changes significantly, making it a sensitive indicator of progress. If you're using weight management strategies—including lifestyle changes or, for eligible adults, prescription medication like GLP-1 treatment—tracking waist size alongside weight provides motivation and insight into health improvements.
What's the difference between waist circumference and waist-to-height ratio?
Waist circumference is the absolute measurement. Waist-to-height ratio divides your waist by your height—a ratio below 0.5 is considered healthy for all adults. For example, someone 170 cm tall should aim for a waist below 85 cm. The ratio accounts for body size, making it useful for comparing individuals of different heights.
Are healthy waist sizes different for older adults?
NHS guidelines don't differ significantly by age, but muscle naturally decreases with age while fat increases—so maintaining a healthy waist size becomes increasingly important for health in older age. If you're uncertain about what's healthy for you personally, discuss your specific waist measurement and health risk with your GP, who can contextualise it with your individual health history.
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.