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 Are UK Health Metrics and Why Do They Matter?
UK health metrics form the foundation of how the NHS assesses weight and wellbeing across the population. These standardized measurements — including BMI, waist circumference, and weight in stone and kilograms — help healthcare professionals understand individual health risks and guide weight management decisions. Whether you're checking your own health status or understanding NHS health advice, these metrics provide crucial context. MyWeightCheck offers free BMI calculator and weight converter tools to help you understand where you stand against NHS guidance and healthy weight UK benchmarks.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 UK Health Metrics Work in Practice
UK health metrics combine several measurements to create a complete picture of health status. BMI (Body Mass Index) remains the primary screening tool used by the NHS, calculated by dividing weight in kilograms by height in metres squared. However, BMI alone has limitations — it doesn't distinguish between muscle and fat, so the NHS also recommends measuring waist circumference as an indicator of central fat storage.
Key metrics include:
- BMI range: 18.5–24.9 is considered healthy weight
- Waist circumference: under 94cm for men, under 80cm for women indicates lower risk
- Weight measured in both stone (UK standard) and kilograms (clinical standard)
- Ethnicity-adjusted thresholds for South Asian, Black African, and Chinese populations, who face higher health risks at lower BMI levels
These measurements work together to provide NHS health guidance that's individualized and evidence-based.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Eligibility, Access, and Your Next Steps
Understanding your UK health metrics is the first step toward informed weight management. If your measurements fall outside healthy ranges, the NHS provides structured support through tiered weight management services. Tier 1 includes self-help resources and digital tools like our free BMI calculator and weight converter. Tier 2 offers primary care-based programmes, while Tier 3 provides specialist multidisciplinary services.
To access NHS weight management guidance:
- Book an appointment with your GP to discuss your individual health picture
- Use MyWeightCheck's free health calculators to understand your current metrics
- Ask your GP about referral to local tier 2 or tier 3 services if appropriate
- Explore evidence-based lifestyle changes alongside any professional support
Your GP can provide personalized NHS health advice based on your specific circumstances.
- 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 are the main UK health metrics I should track?
The primary UK health metrics are BMI (Body Mass Index), waist circumference, and weight in stone or kilograms. The NHS uses these together to assess health risk. BMI ranges from 18.5–24.9 for healthy weight, but waist measurement also matters — under 94cm for men and 80cm for women indicates lower cardiovascular risk. MyWeightCheck's free BMI calculator helps you find where you stand.
Why does the NHS use different BMI thresholds for some ethnic groups?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage face higher risks of type 2 diabetes and heart disease at lower BMI levels. The NHS recommends lower thresholds for these groups — healthy weight starts at BMI 18.5–22.9 rather than 18.5–24.9. This reflects real health differences and ensures more appropriate screening.
How do I know if my measurements put me at health risk?
Use our free weight converter and BMI calculator to check your current metrics against NHS guidance. If your BMI is 25 or above, or your waist circumference exceeds NHS recommendations, contact your GP for personalized NHS health advice. Your doctor can assess your individual risk based on your complete health picture, not just numbers.
What's the difference between UK stone measurements and kilograms?
In the UK, people typically refer to weight in stone and pounds, while NHS clinicians use kilograms for precision. One stone equals 6.35 kilograms. MyWeightCheck's free weight converter instantly translates between both — essential since most NHS guidance uses kilograms but UK adults think in stone.
Can I improve my health metrics without medication?
Yes — the NHS recommends starting with lifestyle changes: reducing calorie intake by 500 kcal daily (roughly 0.5kg weight loss weekly), increasing physical activity, and eating a balanced diet. Many people see significant health improvements through these changes alone. Your GP can discuss whether additional support, including medication, might help alongside lifestyle changes.
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.