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
Am I overweight? How to know using NHS guidelines
Whether you're overweight depends on your height, weight, and individual health factors. The best way to find out is by calculating your BMI (body mass index) and comparing it against NHS guidelines. Our free BMI calculator above will instantly show you where you fall on the NHS weight scale. In the UK, a healthy weight is typically defined as a BMI between 18.5 and 24.9, though thresholds differ for people of South Asian, Chinese, Black African, and Black Caribbean heritage. Even if your BMI is in the overweight range, your GP can provide personalised advice about what it means for your health and whether action is needed.
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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.
Understanding overweight according to NHS guidance
According to NHS weight management guidance, being overweight means having a BMI between 25.0 and 29.9. This is distinct from obesity (BMI 30 or above) and healthy weight (BMI 18.5–24.9). However, BMI is just one screening tool — it doesn't distinguish between muscle and fat, so athletes or very muscular individuals may have a high BMI without excess body fat.
Your waist measurement also matters. The NHS recommends checking your waist circumference:
- Men: over 94cm (37 inches) suggests increased health risk
- Women: over 80cm (31.5 inches) suggests increased health risk
Ethnicity affects health risk at the same BMI. South Asian and Black African adults face higher health risks at lower BMI levels, which is why the NHS recommends lower thresholds for these groups. Use our free BMI calculator on this page to check your exact BMI instantly — it accounts for your height and weight, and will tell you which category you fall into according to current UK health standards.
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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.
What should I do if I'm overweight?
If your BMI is in the overweight range, the NHS recommends starting with lifestyle changes: a balanced, calorie-controlled diet and regular physical activity. Even a 5–clinically studied weight loss can improve your health markers like blood pressure and blood sugar levels.
Your GP can help you access free weight management support through the NHS Weight Loss Plan or local community weight management services. If you have weight-related health conditions like high blood pressure, type 2 diabetes, or sleep apnoea, your GP may refer you to specialist tier 3 services. For ongoing tracking, our free progress tracker helps you monitor your weight loss journey month by month. Always consult your GP before starting any new diet or exercise programme, especially if you have existing health conditions.
- 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 difference between overweight and obese according to NHS guidelines?
The NHS defines overweight as a BMI of 25.0–29.9 and obese as 30.0 or above. Both indicate a health risk, but obesity requires more urgent intervention. Your GP can advise on the appropriate next steps based on your individual health profile and any weight-related health conditions.
Is BMI the only way to tell if I'm overweight?
No. BMI is a useful screening tool but has limitations — it doesn't account for muscle mass, bone density, or where fat is stored. Your waist circumference, overall fitness level, and health markers like blood pressure and cholesterol are equally important. A holistic health assessment from your GP is always recommended.
Can I be overweight but still healthy?
Yes. Some people with a BMI in the overweight range have no weight-related health conditions and good cardiovascular fitness. However, carrying excess weight typically increases risks over time. Your GP can assess your individual risk factors and advise whether weight loss is medically necessary for you.
How much weight should I aim to lose if I'm overweight?
The NHS recommends losing no more than 0.5–1kg per week for sustainable results. A modest loss of 5–10% of your body weight can improve blood pressure, blood sugar, and cholesterol levels. gradual weight management is not recommended and can be harmful. Your GP or a dietitian can set a personalised target based on your health.
What free NHS support is available if I'm overweight?
The NHS offers the free Weight Loss Plan, local community weight management services, and GP-led behaviour change support. If you're overweight with health conditions, your GP can refer you to specialist tier 3 services. Use our free BMI calculator and weight converter to track your starting point, then speak to your GP about available support in your area.
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.