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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Understanding BMI Weight Scales: NHS Guidance
A BMI weight scale measures your body mass index—a key health indicator used by the NHS to assess whether you're at a healthy weight. Your BMI is calculated using your weight and height, and it helps identify potential health risks linked to excess weight. The NHS uses specific BMI categories to guide health recommendations. While BMI isn't perfect and has limitations, it remains a useful screening tool that your GP can discuss with you to understand your personal health context. Use our free BMI calculator above to check your BMI instantly and see where you fall on the NHS weight scale.
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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.
What the NHS BMI Weight Scale Shows
The NHS BMI weight scale divides adults into four main categories, each indicating different health risk levels:
- Underweight (BMI below 18.5): May indicate nutritional deficiency or other health concerns
- Healthy weight (BMI 18.5–24.9): Associated with lowest health risk
- Overweight (BMI 25.0–29.9): Increased risk of type 2 diabetes, heart disease, and high blood pressure
- Obese (BMI 30.0 and above): Significantly elevated risk of serious health conditions
The bmi formula is straightforward: weight (kg) divided by height (m) squared. For example, if you weigh 70kg and are 1.73m tall, your BMI is approximately 23.4—a healthy weight range according to NHS guidance. Your GP can help you understand what your specific BMI means for your individual health and circumstances.
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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 Weight Management Support and Your Next Steps
If your BMI falls outside the healthy range, the NHS offers a structured weight management pathway starting with support from your GP. The NHS recognises that sustainable weight change requires personalised support, not just monitoring a bmi weight scale. Your GP can refer you to local weight management services, discuss lifestyle changes, and explore options like structured diet programmes or physical activity support.
For adults with a BMI above 30, or 27–29.9 with weight-related health conditions, prescription weight management treatments may be considered through specialist NHS services. This might include medications like Mounjaro or Wegovy, always alongside lifestyle changes. The NHS recommends losing weight gradually—around 0.5–1kg per week—for sustainable results. Your GP is the best starting point for understanding your personal BMI context and available support.
- 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 BMI weight scale categories does the NHS use?
The NHS uses four BMI categories: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), and obese (30.0+). These categories help identify health risks, though BMI has limitations and doesn't account for muscle mass or where fat is stored.
How do I calculate my BMI using the weight scale method?
Divide your weight in kilograms by your height in metres squared. For example: 70kg ÷ (1.73 × 1.73) = BMI of 23.4. Our free BMI calculator above does this instantly—just enter your weight and height in UK measurements.
Are NHS BMI thresholds the same for all ethnic groups?
No. The NHS recommends lower thresholds for adults of South Asian, Chinese, Black African, and Black Caribbean heritage due to higher health risks at lower BMI levels. A GP can discuss whether adjusted thresholds apply to you.
What are the main limitations of the BMI weight scale?
BMI doesn't distinguish between muscle and fat, doesn't measure where fat is stored, and may be less accurate for elderly adults or very muscular individuals. Waist measurement and overall health context matter too—your GP can advise.
When should I contact my GP about my BMI weight scale reading?
Contact your GP if your BMI is consistently below 18.5 or above 25, especially if you have weight-related symptoms like fatigue, joint pain, or sleep problems. Your GP can assess your personal health and discuss support options. ```
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.