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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NHS Health Weight — Your Guide to Healthy Weight Management
The NHS defines healthy weight based on your height using BMI (Body Mass Index) and waist measurement. For most UK adults, a healthy BMI is between 18.5 and 24.9. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI starts at 18.5 but the upper limit is 22.9 instead of 24.9. This is because these groups face higher health risks from excess weight at lower BMI levels. Understanding your own healthy weight range is the first step towards sustainable weight management and better long-term health.
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.
What Does the NHS Say About Healthy Weight?
According to NHS health guidance, a healthy weight depends on your height, age, and ethnicity. The NHS uses Body Mass Index (BMI) as the primary screening tool, alongside waist circumference measurement. A healthy BMI for most adults is 18.5–24.9 kg/m². For South Asian and other at-risk ethnic groups, the upper limit is lower at 22.9.
- Healthy weight: BMI 18.5–24.9 (or 18.5–22.9 for South Asian, Chinese, Black African, or Black Caribbean adults)
- Overweight: BMI 25.0–29.9
- Obese: BMI 30.0 and above
The NHS also measures waist circumference because where you carry weight matters. For men, a waist over 94cm (37 inches) signals increased health risk; over 102cm (40 inches) is high risk. For women, these thresholds are 80cm (31.5 inches) and 88cm (34.5 inches). Use our free BMI calculator above to find your personal BMI and see where you fall on the NHS scale.
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.
How Can You Achieve a Healthy Weight?
The NHS recommends a gradual approach to weight management — aim to lose no more than 0.5–1 kg per week for sustainable results. This typically requires a calorie deficit of around 500 calories daily, combined with increased physical activity. The NHS Weight Loss Plan offers free support through your GP, including behaviour change advice and access to community weight management programmes.
For some people, prescription weight loss medication may be appropriate. The NHS funds medications like GLP-1 injections through specialist tier 3 weight management services, though access varies by region and waiting lists can be lengthy. Your GP can assess whether specialist referral is suitable for you. You can also convert your weight between kg, stone, and lbs using our free weight converter to track progress in whichever units feel most familiar.
- 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 a healthy weight according to NHS guidance?
A healthy BMI for most UK adults is 18.5–24.9 kg/m². For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a healthy BMI of 18.5–22.9. Your GP can help determine your individual healthy weight range based on your height, age, and health conditions.
How quickly should I aim to lose weight according to the NHS?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week for safe, sustainable weight loss. This typically requires a calorie deficit of around 500 calories per day, combined with increased physical activity. Very gradual weight management can lead to muscle loss and is not recommended without medical supervision.
Can I get NHS weight loss support and medication?
Yes. Start with your GP who can refer you to tier 3 specialist weight management services if appropriate. The NHS may fund prescription weight loss medications like GLP-1 injections for eligible adults, though regional availability varies. Private prescribing is also available through online prescribers if you don't want to wait for NHS referral.
Why are BMI thresholds lower for some ethnic groups in the UK?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage develop weight-related health conditions (like type 2 diabetes and heart disease) at lower BMI levels than white Europeans. The NHS uses lower thresholds for these groups to identify health risks earlier and offer earlier intervention.
What is waist circumference and why does the NHS measure it?
Waist circumference measures where you carry excess fat. Central (belly) fat is more strongly linked to cardiovascular disease and diabetes than fat carried elsewhere. The NHS measures it alongside BMI because two people with the same BMI can have very different health risks depending on waist size.
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.