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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BMI Over 30: What the NHS Says About Your Health
A BMI over 30 is classified as obese according to NHS guidelines. This means your weight may be affecting your health and increasing your risk of serious conditions like type 2 diabetes, heart disease, and high blood pressure. The good news is that the NHS offers support to help you manage your weight safely. Even a modest weight loss of 5–10% can bring significant health benefits. Our free BMI calculator above can help you check your exact BMI and see where you fall within the NHS categories.
10,000+ calculations today · NHS-aligned thresholds · 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/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 uses standardised BMI range categories to assess whether weight is within a healthy level. A BMI over 30 is classified into three subcategories:
- Class I (30–34.9): Obese — increased health risk
- Class II (35–39.9): Severely obese — substantial health risk
- Class III (40+): Very severely obese — very high health risk
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower healthy BMI thresholds. A BMI of 27.5 or above may indicate increased health risk for these groups due to genetic and metabolic factors.
The BMI formula (weight in kg ÷ height in metres²) is the same for all adults, but it's important to understand that BMI limitations exist — it doesn't distinguish between muscle and fat or account for where fat is stored. Your GP can offer personalised health assessment beyond BMI alone.
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.
NHS Support and Weight Management Pathway
If your BMI is over 30, the NHS offers a structured weight management pathway to help. Your GP can assess your health, discuss weight loss options, and refer you to specialist services if needed. This typically involves:
- Tier 1: Self-help tools, digital programmes, and community support
- Tier 2: Primary care-led behaviour change programmes through your GP
- Tier 3: Specialist multidisciplinary weight management services where medication may be prescribed
- Tier 4: Bariatric (weight loss) surgery for severe obesity with health complications
Access to specialist services varies by region. Contact your GP to discuss which support is available in your area and whether you qualify for NHS-funded weight management treatment.
- 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 a BMI over 30 always a health risk?
A BMI over 30 increases risk of serious health conditions including type 2 diabetes, heart disease, and stroke. However, individual health depends on many factors. Your GP can assess your personal health risk, considering your medical history, fitness level, and where your weight is distributed. Some people with a higher BMI are healthier than others with lower BMI.
How much weight do I need to lose to reduce health risks?
The NHS recommends losing 5–10% of your body weight to see meaningful health benefits. This modest loss can improve blood pressure, blood sugar control, and reduce joint strain. Sustainable weight loss is typically 0.5–1 kg per week. Use our free progress tracker to log your weight loss journey and celebrate incremental improvements.
What should I do if my BMI is over 30?
Book an appointment with your GP to discuss your health and weight. Your GP can check for weight-related conditions, assess your individual risk, and discuss support options available to you — including diet advice, exercise programmes, and referral to specialist weight management services if appropriate.
Can I access prescription weight loss medication on the NHS if my BMI is over 30?
You may be eligible for prescription weight loss medication through NHS specialist weight management services if you have a BMI over 30 or 27–29.9 with weight-related health conditions. However, access varies by region and typically requires referral from your GP to a tier 3 service. Waiting times can be significant in many areas.
How is BMI calculated and does it have limitations?
BMI is calculated as weight (kg) divided by height (metres) squared. The BMI calculator on this page does this instantly. However, BMI has limitations — it doesn't account for muscle mass, bone density, or where fat is stored on your body. Your GP may also measure waist circumference and assess other health markers for a complete picture of 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.