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
Understanding Their Weight — A UK Health Perspective
Weight is a complex health measure influenced by genetics, lifestyle, medical conditions, and environment. Understanding healthy weight in a UK context means looking beyond just a number on the scales. Whether you're thinking about your own weight or someone else's, it helps to know how NHS guidance defines healthy weight, what factors affect it, and what evidence-based approaches can support better health outcomes. Our free BMI calculator and weight converter can help you understand where weight falls within UK health ranges.
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.
What Makes a Healthy Weight in the UK?
The NHS defines healthy weight using BMI (body mass index), which takes height and weight into account. For most UK adults, a healthy BMI falls between 18.5 and 24.9. However, BMI has important limitations — it doesn't distinguish between muscle and fat, so athletes or very muscular people may have a higher BMI but low body fat.
- For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds (18.5 to 22.9) because these groups face higher health risks at lower weights
- Healthy weight also depends on waist circumference — excess belly fat carries higher health risk than fat distributed elsewhere
- Use our free BMI calculator above to check whether a given weight falls into the healthy range for a specific height
Weight is just one part of overall health. Someone at a healthy weight but sedentary faces different health challenges than someone above healthy weight but very active.
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.
Factors That Affect Weight and Weight Management
Weight is influenced by many factors beyond diet and exercise. Genetics account for approximately 40% of weight variation; some people naturally weigh more or less at the same height. Medical conditions like thyroid disease, polycystic ovary syndrome (PCOS), and type 2 diabetes affect weight regulation. Age, medications, sleep quality, stress, and hormonal changes all play roles.
For sustainable weight management, the NHS recommends a balanced approach: gradual calorie deficit (around 500 kcal/day for approximately 0.5kg weekly loss), regular physical activity, and behaviour change support. Our free progress tracker helps log weight changes over time, and our weight converter makes it easy to track progress across UK measurements (stone, pounds, and kilograms).
- 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 is the healthy weight range for a specific height in UK measurements?
To find the healthy weight range, use the formula: 18.5 × height(m)² = lower bound; 24.9 × height(m)² = upper bound. For example, at 5ft 8in (1.73m), healthy weight is approximately 55–75kg (8st 10lbs to 11st 10lbs). Use our free BMI calculator above to check instantly for any height and weight combination.
Is BMI an accurate measure of health?
BMI is a useful screening tool but has limitations. It doesn't account for muscle mass, so athletes may have high BMI but low body fat. It also doesn't reflect where fat is stored or overall fitness. The NHS recommends using BMI alongside waist circumference and other health measures for a fuller picture.
Can someone at an unhealthy weight still be healthy?
Health is multifactorial. Someone above healthy weight but very active with good fitness, normal blood pressure, and stable blood sugar may have good health markers. Conversely, someone at healthy weight but sedentary faces health risks. This is why weight management is just one part of overall wellness.
What does NHS guidance say about safe weight loss?
The NHS recommends losing 0.5 to 1kg per week (1 to 2lbs weekly) for sustainable, healthy weight loss. This typically requires a calorie deficit of around 500 kcal daily. Faster loss is possible with medical support but increases the risk of muscle loss and nutrient deficiencies.
Are there prescription medications available for weight management in the UK?
Yes. Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, may be eligible for prescription weight management medications like Mounjaro or Wegovy. These are prescription-only and require clinical assessment through either NHS specialist services or private prescribing. Our GLP-1 weight loss calculator can help you explore potential weight loss projections with these medications.
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.