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 Is Average Body Mass?
Average body mass in the UK refers to the typical weight of adults based on their height and body composition. According to the latest Office for National Statistics (ONS) data, the average UK adult man weighs approximately 85.7 kg (13 stone 7 lbs) at a height of 175.3 cm (5 ft 9 in), whilst the average UK adult woman weighs approximately 71.6 kg (11 stone 3 lbs) at a height of 161.6 cm (5 ft 3.5 in). However, average weight doesn't necessarily mean healthy weight. Your personal healthy weight depends on your individual height, body composition, and overall health profile. Use our free BMI calculator above to check where your weight falls on the NHS health 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.
Average UK Body Mass & BMI Categories
The average UK adult man has a BMI of approximately 27.9, and the average UK adult woman has a BMI of approximately 27.4. These figures fall into the overweight category according to NHS guidelines (BMI 25.0–29.9), rather than the healthy weight range (18.5–24.9). This reflects a broader trend: around 63% of UK adults are classified as overweight or obese. It's important to note that average doesn't equal healthy—many UK adults are heavier than the NHS recommends for optimal health outcomes. Your personal healthy weight range depends on your exact height. For example, at 175 cm (5 ft 9 in), a healthy BMI range would be approximately 55–75 kg (8 st 10 lb–11 st 11 lb). Use our free weight converter to translate your weight between kg, stone, and pounds, then check your BMI instantly using the calculator on this page.
- Healthy BMI range: 18.5–24.9
- Overweight range: 25.0–29.9
- Obese range: 30.0 and above
- South Asian, Chinese, Black African, and Black Caribbean adults: Lower thresholds apply due to higher health risks at lower BMI levels
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.
Understanding Body Composition Beyond Average Weight
Average body mass and BMI are useful screening tools, but they don't tell the complete picture of your health. Body composition—the ratio of lean body mass (muscle, bone, organs) to body fat—matters significantly. Two people at the same weight and height can have very different body compositions and health profiles. Body fat percentage is often a more meaningful measure than weight alone. A high percentage of visceral fat (fat stored around organs) poses greater health risks than subcutaneous fat (under the skin). Additionally, lean body mass decreases naturally with age, so older adults may have higher BMI yet still be relatively healthy. For personalised guidance on whether your body mass is healthy for you, consult your GP, who can assess your overall health context, family history, and any weight-related health conditions you may have.
- 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 average body mass of a UK adult?
According to ONS data, the average UK adult man weighs 85.7 kg (13 st 7 lb) at 175.3 cm tall, and the average UK adult woman weighs 71.6 kg (11 st 3 lb) at 161.6 cm tall. However, these averages fall into the overweight BMI category, not the healthy weight range recommended by the NHS.
Does average body weight mean healthy body weight?
No. Average and healthy are different. Around 63% of UK adults are overweight or obese according to NHS classifications. Your healthy weight depends on your individual height, age, muscle mass, and health status. Use the BMI calculator on this page to check your personal healthy weight range.
What is a healthy BMI for UK adults?
The NHS recommends a healthy BMI of 18.5–24.9 for most adults. However, people of South Asian, Chinese, Black African, or Black Caribbean heritage should aim for 18.5–22.9 due to higher health risks at higher BMI levels. Your GP can advise on your personal healthy range.
How is average body mass calculated?
Average body mass is calculated by collecting weight data from large population samples (like the ONS) and determining the mean weight across age groups, genders, and heights. Individual averages vary significantly by age, genetics, muscle mass, and lifestyle factors.
Is body fat percentage more important than average weight?
Both matter. Body fat percentage gives a clearer picture of health than weight alone, as it distinguishes between muscle and fat. Two people at the same weight can have very different body compositions and health risks. Ask your GP about body composition assessment if you're concerned about your health.
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.