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
Is My Weight in the Obese Range?
Obese weight is defined by BMI rather than a specific number on the scales, as height affects what's considered obese. According to NHS guidelines, an obese BMI is 30 or above. However, for adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, obesity thresholds start at a lower BMI of 27.5 or above due to higher health risks at lower weights. Use our free BMI calculator above to check your personal BMI instantly and find out if your weight falls into the obese category.
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 — Overweight and Obese Thresholds
According to NHS guidelines, BMI categories are:
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9 (also called "overweight bmi")
- Obese Class I: BMI 30.0–34.9
- Obese Class II: BMI 35.0–39.9
- Severely obese (Class III): BMI 40.0 and above
An obese bmi uk starts at 30. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the nhs overweight threshold is lower: healthy weight is BMI 18.5–22.9, overweight is 23.0–27.4, and obesity starts at 27.5. These lower thresholds reflect evidence that these groups face higher cardiovascular and diabetes risks at lower BMI levels. Your GP can explain what your personal BMI means for your health and discuss your individual risk factors.
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.
Waist Measurement — A Complementary Health Check
While BMI is a useful screening tool, waist measurement also matters for health risk. The NHS recommends:
- Men: increased risk if over 94 cm (37 inches); high risk if over 102 cm (40 inches)
- Women: increased risk if over 80 cm (31.5 inches); high risk if over 88 cm (34.5 inches)
Waist measurement is a useful indicator of central fat storage, which poses greater health risks than fat distributed elsewhere. Even if your BMI is in the healthy range, a large waist circumference can indicate waist measurement health risk. Combining your BMI result with your waist measurement gives a more complete picture of your health. If you're concerned about your weight, your GP can discuss a personalized approach tailored to your circumstances.
- 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 does it mean if I have an obese weight?
An obese BMI (30 or above) indicates a higher health risk for conditions like type 2 diabetes, cardiovascular disease, and certain cancers. It's not a judgement — it's a health indicator. Your GP can assess your individual situation and discuss support options, including lifestyle changes or prescription treatments if appropriate.
Is obese weight the same as overweight?
No. Overweight is BMI 25–29.9; obese is BMI 30 and above. Both indicate health risks, but obesity carries a higher risk level. The exact threshold depends on your height and, for some ethnic groups, may start at a lower BMI according to NHS guidance.
Can I use the BMI calculator to check if I'm obese?
Yes. Enter your height and weight into our free BMI calculator above. It will instantly show you your BMI and which NHS category you fall into — whether that's healthy weight, overweight, or obese. This gives you a clear, evidence-based starting point.
What should I do if my BMI is in the obese range?
Start by discussing your health with your GP. They can assess your individual risk factors, medical history, and lifestyle. Options may include structured weight loss programmes, dietary support, increased physical activity, or in some cases, prescription weight management treatments available through NHS specialist services or private options.
Do the obese weight thresholds differ for different ethnic groups?
Yes. The NHS recommends lower BMI thresholds for adults of South Asian, Chinese, Black African, and Black Caribbean descent because these groups have higher health risks at lower BMI levels. If this applies to you, discuss your personal thresholds with your GP to get tailored guidance.
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.