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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Working Out An Average Weight — UK Health Guide
Working out your average weight is a useful step in understanding your health and tracking progress over time. Whether you're monitoring weight for fitness, health management, or calculating your BMI, knowing how to find your average weight accurately helps you see the bigger picture beyond day-to-day fluctuations. This UK health guide explains the methods, why averages matter, and how they fit into NHS weight management guidance.
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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.
Why Calculate Your Average Weight?
Weight naturally fluctuates day to day due to hydration, meals, hormones, and exercise. Calculating an average over a week or month smooths out these fluctuations and gives you a true picture of whether you're maintaining, gaining, or losing weight. This is especially useful if you're tracking progress or assessing your healthy weight range using UK BMI guidelines.
- Day-to-day weight can vary by 1–2 kg (2–4 lbs) due to water retention and food intake
- An average eliminates noise and shows real trends
- Averages are more reliable for calculating BMI changes over time
- Regular tracking supports weight management and health monitoring
If you're working towards a specific healthy weight for your height, or using weight management tools like our free BMI calculator and weight converter above, averaging your weekly weight gives you meaningful data to work with rather than reacting to daily fluctuations.
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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 Calculate Your Average Weight
Step 1: Weigh yourself on the same day and time each week (ideally morning, after toilet, before eating). Record your weight in kg, stone, or lbs—whichever you prefer.
Step 2: Collect data for at least 4 weeks to establish a reliable average.
Step 3: Add all your weekly weights together and divide by the number of weeks. For example: (70 + 70.5 + 69.8 + 70.2) ÷ 4 = 70.1 kg average.
Use our free progress tracker to log your weekly weights automatically and see your average calculated for you. This removes the maths and lets you focus on your health goals. Once you have your average weight and height, use our weight converter to switch between kg, stone, and lbs, then calculate your BMI using the calculator on this page.
Once you've established your average weight, you can assess it against NHS healthy weight ranges for your height. A healthy BMI is between 18.5 and 24.9 for most UK adults (lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage). If your average weight puts you outside the healthy range and you're interested in support, your GP can discuss options including lifestyle changes or, if eligible, prescription weight management approaches. Individual circumstances vary—always speak to your healthcare team about what's right for you.
- 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 often should I weigh myself to work out an accurate average?
Once per week on the same day and time (ideally morning, after the toilet, before food) gives the most reliable average. Weighing daily introduces noise from water retention and food intake. A weekly weigh-in removes these fluctuations and shows genuine weight trends over time.
What if my weight fluctuates a lot week to week—is the average still useful?
Yes. Even with significant weekly variation, a monthly or quarterly average reveals your true direction. This is why weight management programmes and health monitoring focus on averages rather than individual weigh-ins. Fluctuation is normal; the trend matters.
Do I need to convert my weight to kg to work out the average?
No. Calculate your average in whichever unit you prefer (stone, lbs, or kg). Once you have your average, use our free weight converter to switch between units if needed for BMI calculations or health comparisons.
How does my average weight relate to a healthy BMI?
Your average weight and height determine your BMI using the formula: weight (kg) ÷ height (m)². A healthy BMI is 18.5–24.9 for most UK adults. Use our free BMI calculator above to check your BMI once you have your average weight, or speak to your GP for personalised advice.
Can I use my average weight to assess whether I need weight loss support?
Your average weight is a starting point. NHS guidance suggests adults with a BMI of 30 or above, or 25–29.9 with weight-related health conditions, may benefit from support. Your GP can assess your individual situation and discuss options including lifestyle changes or prescription weight management if eligible.
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.