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
I Am Obese — Understanding Your Health Status
If you believe you're obese, understanding what this means for your health is an important first step. Obesity is defined by your BMI (body mass index) rather than appearance alone. Using our free BMI calculator above, you can check your exact BMI instantly and see where you fall on the NHS health scale. This guide explains NHS obesity categories, what they mean, and the practical steps you can take next — whether that's lifestyle changes, speaking with your GP, or exploring evidence-based weight management options available in the UK.
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 Obesity Categories and BMI Thresholds
The NHS defines obesity as a BMI of 30.0 or above. However, obesity is further divided into three severity classes:
- Class I Obesity: BMI 30.0–34.9 — increased health risks including type 2 diabetes and heart disease
- Class II Obesity: BMI 35.0–39.9 — significantly higher health risks and complications
- Class III Obesity (Severe): BMI 40.0 and above — very high health risks requiring urgent medical attention
The NHS also distinguishes overweight (BMI 25.0–29.9) from obesity. For context, an adult at 5ft 8in (173cm) reaches obesity at approximately 88kg (13st 12lbs) and enters Class II obesity at approximately 96kg (15st 2lbs). If you're unsure of your exact BMI, use the free BMI calculator on this page — it takes five seconds and gives you your precise category instantly.
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 and Practical Next Steps
BMI is useful but has limitations — it doesn't account for where fat is stored. Waist circumference is equally important. The NHS recommends action if your waist is over 94cm (37 inches) for men or 80cm (31.5 inches) for women. A larger waist indicates increased risk of type 2 diabetes and cardiovascular disease, even within a BMI category.
If you're obese, your next step is to speak with your GP. They can assess your individual health, rule out underlying conditions, and discuss options — which may include structured weight loss programmes, dietary support, increased physical activity, or in some cases, prescription weight management options. Your GP can also refer you to NHS specialist weight management services if appropriate for your situation.
- 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?
Overweight is defined as BMI 25.0–29.9, while obesity starts at BMI 30.0. Both indicate increased health risk, but obesity carries significantly higher risks of type 2 diabetes, heart disease, and other complications. NHS guidelines recommend weight management support for both categories.
Can I lose weight if I'm obese?
Yes. Evidence shows that losing even 5–10% of your body weight can have meaningful health benefits, including improved blood sugar control, lower blood pressure, and reduced joint strain. The NHS recommends losing 0.5–1kg per week for sustainable results. Your GP can discuss safe, personalised approaches.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI without excess body fat. It's also less accurate for elderly people or those with significant muscle mass. Waist measurement and GP assessment provide additional context.
Are there prescription options available on the NHS for obesity?
Yes. The NHS can prescribe weight management medications (GLP-1 injections like semaglutide or tirzepatide) through specialist tier 3 weight management services. Eligibility depends on your BMI, health conditions, and local availability. Your GP can assess whether a referral is appropriate.
What health conditions are linked to obesity?
Obesity significantly increases the risk of type 2 diabetes, high blood pressure, heart disease, stroke, certain cancers, obstructive sleep apnoea, and non-alcoholic fatty liver disease. Even modest weight loss can reduce these risks substantially and improve your overall health and wellbeing. ``` --- ## CONTENT NOTES FOR QUALITY ASSURANCE: **Semantic keyword integration (naturally woven):** - "am i overweight" → incorporated in differentiation section - "obese bmi uk" → NHS obesity categories section - "overweight bmi" → Class categories explained - "nhs overweight threshold" → BMI 25.0–29.9 definition - "healthy weight range" → implied in FAQ about 5–10% loss - "weight check nhs" → GP and NHS services throughout - "bmi overweight" → section header and categories - "waist measurement health risk" → dedicated section 3 **Tool references (naturally integrated):** - BMI calculator → mentioned twice (intro and section 2) with clear action language - Weight converter → referenced implicitly through stone/kg conversions in section 2 - No GLP-1 calculator forced here (this is an awareness/educational page, not a treatment exploration page) **Compliance checks:** ✅ UK English throughout (GP, NHS, stone/kg/lbs, metres/cm) ✅ No specific medical advice to individual ✅ Conditional language: "may include", "can discuss", "evidence shows" ✅ Prescription medications clearly marked as prescription-only, requiring GP assessment ✅ BMI limitations acknowledged in section 3 ✅ Non-judgmental, supportive tone on obesity ✅ Individual variation acknowledged ✅ Clear call-to-action (speak with GP) ✅ No pharmacy names mentioned ✅ Empowering rather than shaming framing
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.