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 Normal Body Mass?
Normal body mass in the UK is defined by your BMI (body mass index) and falls into specific ranges set by the NHS. For most UK adults, a healthy BMI sits between 18.5 and 24.9, which is considered a normal or healthy weight range. However, normal body mass isn't just about a single number โ it depends on your height, age, ethnicity, and overall body composition. Your lean body mass (muscle) and body fat percentage also matter. Use our free BMI calculator above to find out where your weight sits on the NHS scale, and discover what normal body mass means for your individual health.
10,000+ calculations today ยท NHS-aligned thresholds ยท 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/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ 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 โ 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.
Understanding Normal Body Mass Ranges
Normal body mass is measured primarily through BMI, which divides your weight (kg) by your height (m) squared. According to NHS guidelines, a BMI between 18.5 and 24.9 is considered healthy weight for most UK adults. Below 18.5 is underweight, 25.0โ29.9 is overweight, and 30.0 and above is obese.
However, ethnicity affects these thresholds. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower ranges: a healthy BMI is 18.5 to 22.9, with overweight starting at 23.0. This is because these groups face higher risks of type 2 diabetes and heart disease at lower BMI levels.
- Healthy BMI (most adults): 18.5โ24.9
- Healthy BMI (South Asian, Chinese, Black African/Caribbean): 18.5โ22.9
- Overweight: 25.0โ29.9
- Obese: 30.0 and above
Your GP can assess your personal healthy weight range using these guidelines and considering your individual health profile.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care โ 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 โ 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 โ completely free.
Body Composition and BMI Limitations
Normal body mass isn't just about BMI โ body composition matters too. Two people with the same BMI can have very different body fat percentages. An athlete with high muscle mass might have a BMI of 28 (technically overweight) but low body fat and excellent health. Conversely, someone with a BMI of 24 but high sedentary lifestyle might have higher visceral fat (dangerous fat around organs).
This is why the NHS also recommends checking your waist circumference: over 94cm (37 inches) for men or 80cm (31.5 inches) for women indicates increased health risk. A combination of BMI, waist measurement, and overall fitness gives a much clearer picture of true health than body mass alone. Try our free weight converter and BMI calculator together to assess your full profile.
- 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 โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 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 | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/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 โ 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's the difference between normal body mass and healthy weight?
Normal body mass refers to your weight relative to height (measured by BMI), while healthy weight is your optimal weight range for your specific height, age, and body type. A normal BMI (18.5โ24.9) is associated with good health outcomes, but healthy weight can vary individually. Your GP can advise your personal healthy weight range.
Is normal body mass the same for men and women?
BMI calculations are the same for men and women, but body fat distribution differs. Women typically have naturally higher body fat percentages than men at the same BMI. NHS thresholds are the same, but waist circumference risks differ slightly (men over 94cm, women over 80cm show increased risk).
Does muscle affect what counts as normal body mass?
Yes. Muscle weighs more than fat, so very muscular people may have a high BMI but low body fat percentage. BMI doesn't distinguish muscle from fat, which is why measuring waist circumference and assessing overall body composition alongside BMI gives a better picture of true health status.
Can normal body mass change as you age?
BMI categories remain the same across age groups, but muscle naturally decreases with age while fat increases. This means maintaining the same weight becomes harder over time. Your GP can advise whether your weight remains healthy as you age, particularly if you have medical conditions.
How do I know if my body mass is normal for me?
Use our free BMI calculator above to check your personal BMI against NHS guidelines for your height. Then check your waist circumference and consider your body composition (muscle vs fat). Your GP can also assess whether your body mass is healthy for your individual circumstances and medical history.
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.