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 Does a BMI of 30 Mean?
A BMI of 30 puts you into the obese category according to NHS guidelines — the threshold where health risks begin to increase significantly. This doesn't mean you're unhealthy, but it does suggest your GP may recommend lifestyle changes or support to reduce your risk of weight-related conditions like type 2 diabetes, high blood pressure, and heart disease. Understanding where your BMI falls helps you make informed decisions about your health. Use our free BMI calculator above to check your personal BMI and explore what it means for you.
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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 30 Means
The NHS BMI formula divides your weight in kilograms by your height in metres squared. A BMI of 30 is significant because it marks the boundary into the obese category — the first of three obesity classifications. Here are the full NHS BMI categories:
- Under 18.5: Underweight
- 18.5 to 24.9: Healthy weight
- 25.0 to 29.9: Overweight
- 30.0 to 34.9: Obese (Class I)
- 35.0 to 39.9: Obese (Class II)
- 40.0+: Severely obese (Class III)
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy BMI range is lower — 18.5 to 22.9 — because research shows these groups face higher health risks at the same BMI as other populations. At a BMI of 30, your risk of weight-related health conditions is elevated, though individual risk depends on other factors like fitness level, waist measurement, and family history.
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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.
BMI Limitations and What Else Matters
BMI has important limitations. It doesn't distinguish between muscle and fat — a very muscular person may have a high BMI but low body fat percentage. It also ignores where fat is stored; excess weight around the waist carries greater health risk than fat on the hips or thighs. Your GP may also measure your waist circumference — over 94cm (37 inches) for men or 80cm (31.5 inches) for women suggests increased health risk. Blood pressure, cholesterol, blood sugar, and fitness level all matter too. Rather than focusing on BMI alone, consider it one piece of the health puzzle. Your GP can give you personalised guidance on whether your BMI of 30 requires action and what support might help you.
- 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 of 30 dangerous?
A BMI of 30 increases risk of type 2 diabetes, heart disease, and high blood pressure — but it doesn't assures you'll develop these conditions. Risk depends on your overall health, fitness, family history, and where weight is carried. Your GP can assess your individual risk and suggest next steps.
What should I do if my BMI is 30?
Start by booking a GP appointment to discuss your health. They may recommend lifestyle changes — increased physical activity and a modest calorie deficit typically help. Some people benefit from structured support through NHS weight management services or prescription medication if they meet eligibility criteria.
How much weight do I need to lose to get below BMI 30?
It depends on your height. For example, at 5ft 9in (175cm), a BMI of 30 equals approximately 92kg. To reach BMI 29.9, you'd need to lose just under 1kg. Your GP or a dietitian can calculate the target weight range for your specific height.
How is BMI calculated exactly?
The BMI formula is weight in kilograms divided by height in metres squared. For example: if you weigh 90kg and are 1.75m tall, your BMI = 90 ÷ (1.75 × 1.75) = 29.4. Use our free BMI calculator above for gradual improvement in both metric and imperial measurements.
Does a BMI of 30 mean I'm overweight or obese?
At exactly 30, you're at the threshold of the obese category. BMI 25–29.9 is classified as overweight; 30 and above is obese. The distinction matters because health guidance changes — your GP may suggest more structured support or referral to specialist weight management services at BMI 30 or above.
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.