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
Obese Treatment NHS — Understanding Your Weight Status
If you're concerned about your weight and how the NHS classifies obesity, this guide will help you understand where you stand. The NHS defines obesity as a BMI of 30 or above, though the thresholds vary for different ethnic groups. Using our free BMI calculator above, you can instantly check your personal BMI and see which NHS category you fall into. Understanding your weight status is the first step towards accessing the right support and treatment options available through the NHS.
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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.
NHS BMI Categories and Obesity Classification
The NHS uses standardised BMI categories to classify weight status in UK adults. These are based on your weight in kilograms divided by your height in metres squared. According to NHS guidelines:
- Healthy weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obese (Class I): BMI 30.0 to 34.9
- Obese (Class II): BMI 35.0 to 39.9
- Severely obese (Class III): BMI 40.0 and above
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the nhs overweight threshold is lower due to increased health risk at these weights. These groups have a healthy BMI range of 18.5 to 22.9, with overweight starting at 23.0. An obese bmi uk for these groups starts at 27.5 rather than 30.0.
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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.
Waist Measurement and Next Steps
Your BMI is important, but waist measurement also matters for assessing health risk. The NHS recommends checking your waist circumference alongside your BMI, as fat stored around the middle carries greater health risks. Men with a waist over 94cm (37 inches) and women over 80cm (31.5 inches) have increased risk; these thresholds are even lower for South Asian individuals. If you've identified that you fall into the overweight or obese category, speaking to your GP is the next step. Your GP can discuss a weight check nhs assessment and talk through treatment options, which may include lifestyle support, referral to specialist weight management services (tier 3), or prescription weight management medications for eligible individuals.
- 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 my BMI is in the obese range?
A BMI of 30 or above indicates obesity according to NHS classifications. This means your weight relative to your height puts you at increased risk of weight-related health conditions like type 2 diabetes, heart disease, and high blood pressure. However, BMI is a screening tool — it doesn't account for muscle mass or overall fitness. Your GP can assess your individual health picture.
Are the NHS BMI categories different for me if I'm South Asian or Black?
Yes. The NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage because these groups face higher health risks at lower BMI levels. For these groups, the healthy range is 18.5 to 22.9, and obesity starts at 27.5 rather than 30.0. Your GP can apply the appropriate thresholds for your ethnicity.
How can I check if I'm overweight or obese?
The easiest way is to use our free BMI calculator above — enter your weight and height, and it will instantly show you your BMI and which NHS category you fall into. You can also calculate it manually: divide your weight in kilograms by your height in metres squared. Your GP can also check your BMI and waist measurement during a routine appointment.
What NHS treatment options are available for obesity?
The NHS offers support through different tiers. Tier 1 includes self-help resources and community programmes. Your GP can refer you to tier 2 or 3 specialist weight management services, which provide behaviour change support and may offer prescription medications like GLP-1 injections for eligible individuals. Tier 4 (bariatric surgery) is available for severe obesity with significant health complications.
Should I measure my waist as well as my BMI?
Yes. Waist measurement helps identify health risk from fat stored around the abdomen. Combined with BMI, it gives a more complete picture of your health. For men, a waist over 94cm raises health risk; for women, over 80cm. These thresholds are lower for South Asian individuals. You can measure your waist at the midpoint between your lowest rib and hip bone.
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.