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 a Normal Healthy BMI Range According to the NHS?
According to NHS guidance, a normal healthy BMI range for most UK adults is between 18.5 and 24.9. Your BMI (body mass index) is calculated by dividing your weight in kilograms by your height in metres squared. It's one of the most straightforward ways to assess whether you're at a healthy weight for your height. However, BMI is just a screening tool — it doesn't account for muscle mass, bone density, or where fat is stored on your body. Your GP can give you personalised advice about what your BMI means for your individual health.
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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.
NHS BMI Categories and What They Mean
The NHS recognises five main BMI categories for adults:
- Underweight: BMI below 18.5 — may indicate insufficient weight for your height
- Healthy weight: BMI 18.5–24.9 — the target range for most adults
- Overweight: BMI 25.0–29.9 — increased health risk begins here
- Obese (Class I): BMI 30.0–34.9 — significant health risk
- Severely obese (Class III): BMI 40.0 and above — very high health risk
It's important to note that BMI limitations exist. BMI doesn't distinguish between muscle and fat, so athletes or very muscular individuals may have a higher BMI despite being healthy. Additionally, the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage, as these groups face higher cardiovascular and diabetes risk at lower BMI levels. For these populations, a healthy BMI range begins at 18.5–22.9 instead. Use our free BMI calculator above to check your personal BMI instantly and see where you fall on the NHS scale.
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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 Weight Management Support and When to Seek Help
If your BMI falls outside the healthy range, the NHS offers a structured approach to weight management through its four-tier pathway. Tier 1 includes self-help resources, digital tools, and community weight loss programmes available to everyone. Tier 2 involves primary care interventions where your GP may discuss lifestyle changes and refer you to a local weight management service. Tier 3 provides specialist multidisciplinary support, including dietary advice, physical activity programmes, and potentially prescription medications if appropriate. Tier 4 covers bariatric (weight loss) surgery for severe obesity with significant health complications. Your GP is the best starting point — they can assess your individual health, discuss your weight goals, and recommend the right support for you. Even a small weight loss of 5–10% of your body weight can bring meaningful health benefits.
- 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 normal healthy BMI range in the UK?
The NHS defines a normal healthy BMI range as 18.5 to 24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy range is 18.5 to 22.9 due to higher health risks at lower BMI levels. You can calculate your BMI using the formula: weight (kg) divided by height (metres) squared.
What BMI counts as overweight according to NHS guidelines?
The NHS classifies a BMI of 25.0 to 29.9 as overweight. At this level, health risks begin to increase, including type 2 diabetes and cardiovascular disease. If your BMI falls in this range, your GP may discuss lifestyle changes or refer you to a weight management service.
Why does the NHS use different BMI thresholds for some ethnic groups?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage develop type 2 diabetes and heart disease at lower BMI levels than other populations. The NHS therefore recommends a lower healthy range (18.5–22.9) for these groups to better identify health risks early and enable earlier intervention.
Is BMI the only measure of a healthy weight?
No. While BMI is useful as a screening tool, it has limitations — it doesn't account for muscle mass, bone density, or where fat is stored. Waist circumference is also important. The NHS recommends men keep waist circumference under 94cm (37 inches) and women under 80cm (31.5 inches) for reduced health risk.
How do I find out my healthy weight range for my height?
Your healthy weight range depends on your height and can be calculated using the BMI formula. For example, at 1.73m (5ft 8in), a healthy weight falls between approximately 55kg (8st 10lbs) and 74kg (11st 10lbs). Use our free BMI calculator and weight converter above to find your personal healthy range instantly.
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.