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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Average Body Weight By Age in the UK
Understanding how your weight compares to UK averages can provide helpful context for your health. Average body weight varies significantly by age, sex, and height across the UK population. However, what matters most for your individual health is not the average — it's whether your weight falls within a healthy range for your age and height according to NHS guidance. This guide explains UK weight data, how to assess your personal weight, and where to find support if you're concerned about weight management.
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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.
UK Average Body Weight Data by Age Group
According to the Office for National Statistics (ONS) and NHS data, UK adult weights vary considerably across age groups. Men aged 16–24 average around 79 kg (12st 6lbs), increasing to approximately 87 kg (13st 9lbs) by ages 35–44, and reaching peak weight around 89 kg (14st 0lbs) in the 55–64 age group before declining slightly in older age. Women aged 16–24 average around 67 kg (10st 7lbs), rising to approximately 75 kg (11st 12lbs) by ages 35–44. Overall, UK adults average 85.7 kg for men and 71.6 kg for women — though these figures mask substantial individual variation based on height, muscle mass, and genetic factors.
These averages are not health targets. Many UK adults at the national average weight still fall into the overweight or obese BMI categories because average height and body composition vary. Use our free BMI calculator on this page to see where your weight sits relative to NHS healthy weight ranges for your specific height and age.
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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 Healthy Weight Guidance and What "Healthy" Really Means
Rather than focusing on average body weight, the NHS recommends assessing your weight using BMI (Body Mass Index) alongside waist circumference and overall health context. A healthy BMI for most UK adults is 18.5 to 24.9, though lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage — for these groups, the healthy range starts at 18.5 to 22.9 due to higher cardiovascular risk at higher BMI levels.
Weight alone doesn't determine health. A person at the UK average weight may have excellent health markers, whilst someone below average might have health concerns. Age also matters: muscle naturally declines with age, which can affect weight and BMI interpretation. Your GP can provide personalised weight management guidance based on your health history, not population averages. Track your weight trends over time using our free progress tracker to monitor meaningful change rather than comparing yourself to national figures.
- 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.
Is the UK average body weight a healthy weight?
No. The UK average weight doesn't equal a healthy weight. Many UK adults at the national average (85.7 kg for men, 71.6 kg for women) have BMI in the overweight or obese range. Your healthy weight depends on your height, age, and individual health factors. Use an NHS BMI calculator or our free weight converter to check your personal healthy weight range.
Does weight increase naturally with age in the UK?
Yes, average UK weight does tend to increase from young adulthood through middle age, peaking around ages 55–64 before declining slightly. However, this average increase reflects population trends, not biological necessity. Maintaining physical activity and healthy eating habits can help prevent age-related weight gain. Your GP can advise on appropriate weight management for your age and health.
What's the difference between average weight and healthy weight?
Average weight is simply the statistical mean across a population — it's descriptive data about what UK adults typically weigh. Healthy weight is individual to you, determined by your height, age, health conditions, and body composition. A person can be at average weight but unhealthy, or above average and very healthy. BMI provides a better health indicator than comparison to averages.
How can I tell if my weight is healthy for my age?
Calculate your BMI using your height and weight — the NHS BMI healthy range is 18.5 to 24.9 (or 18.5 to 22.9 for South Asian, Chinese, Black African, and Caribbean populations). Also check your waist circumference: over 94 cm for men or 80 cm for women indicates increased health risk. Ask your GP for a personalised assessment rather than relying on age-based averages.
Should I aim to weigh what the UK average is for my age?
No — aim for a weight within the healthy BMI range for your height, not the population average. The UK average weight reflects current population trends (including high rates of overweight and obesity), not a health target. Your GP or NHS weight management services can help set realistic, health-based weight goals tailored to you.
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.