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
NHS Weight Guide for UK Adults
The NHS provides clear guidance on healthy weight for UK adults, based on BMI categories and individual health circumstances. A healthy weight depends on your height, age, and overall health rather than a single number on the scales. The NHS uses evidence-based thresholds to help people understand whether their weight falls within a healthy range, and offers practical support through its weight management pathway. This guide explains NHS weight guidance, how to assess your own weight using standard measures, and what support is available if you want to manage your weight.
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 and Healthy Weight Ranges
The NHS defines healthy weight using BMI (body mass index), which is calculated from your height and weight. According to NHS guidance, a healthy BMI for most adults is between 18.5 and 24.9. You can calculate your personal BMI instantly using our free BMI calculator above.
The NHS weight categories are:
- Underweight: BMI below 18.5
- 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 people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds because these groups face higher health risks at lower BMI levels. Healthy weight for these groups is BMI 18.5 to 22.9, and overweight starts at BMI 23.0.
Clinically BackedWeight Loss
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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.
Why Weight Matters and NHS Support
The NHS recognises that weight affects health and wellbeing. Even modest weight loss—as little as 5 to 10% of your current weight—can improve blood pressure, blood sugar control, and reduce strain on joints. The NHS offers a structured weight management pathway with support at different tiers: self-help resources and digital tools (Tier 1), primary care-based programmes (Tier 2), specialist weight management services (Tier 3), and bariatric surgery for severe obesity (Tier 4).
If you're concerned about your weight, your GP can provide personalised advice and discuss whether specialist support or prescription weight management treatment might be appropriate for you. Use our free weight converter to check your weight in different units, and track your progress with our free progress tracker.
- 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 the NHS?
The NHS defines healthy weight using BMI, with a healthy range of 18.5 to 24.9 for most adults. For South Asian, Chinese, Black African, or Black Caribbean adults, the healthy range is 18.5 to 22.9 due to higher health risk thresholds. Your GP can give you personalised guidance based on your individual health and circumstances.
How do I calculate my BMI using NHS guidance?
BMI is calculated by dividing your weight in kilograms by your height in metres squared. Our free BMI calculator on this page does this instantly—just enter your height and weight. The NHS also provides BMI calculators on the NHS website for reference.
What does the NHS recommend if I am overweight?
The NHS recommends starting with Tier 1 support: using free digital tools, following the NHS Weight Loss Plan, or joining a community weight management programme. If you need additional support, your GP can refer you to Tier 2 or specialist Tier 3 services. Weight loss of 0.5 to 1 kg per week is considered safe and sustainable.
Can the NHS prescribe weight loss medication?
Yes. GLP-1 medications like semaglutide (Wegovy) and tirzepatide (Mounjaro) are available through NHS specialist weight management services for eligible adults. Access is through Tier 3 specialist services and varies by region. Your GP can refer you if you meet clinical criteria.
Does the NHS consider waist measurement as well as BMI?
Yes. Waist circumference is also important: increased risk for men is over 94cm (37 inches) and for women over 80cm (31.5 inches). The NHS recommends using both BMI and waist measurement together to assess health risk. Your GP can discuss both measures with you.
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.