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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NICE UK — Understanding NHS Health Guidance
NICE (the National Institute for Health and Care Excellence) is the independent UK body that develops evidence-based guidance for the NHS and healthcare professionals. Whether you're interested in weight management, healthy weight ranges, or understanding your BMI within UK health standards, NICE provides the gold-standard recommendations that shape NHS care across the country. This guide explains what NICE is, how it influences UK health policy, and where to find practical resources to support your health goals.
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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.
NICE Guidance on Weight Management and Health
NICE (National Institute for Health and Care Excellence) is an independent organisation that produces evidence-based guidance for the NHS, public health services, and social care. NICE develops recommendations on diagnosis, treatment, and prevention of diseases and conditions across the UK.
- Weight Management Guidance: NICE has published comprehensive guidance on obesity and weight management in adults, including criteria for prescription weight loss medications like tirzepatide (Mounjaro) and semaglutide (Wegovy). This guidance shapes which patients are eligible for treatment on the NHS.
- BMI Standards: NICE aligns with NHS BMI categories: healthy weight is 18.5–24.9, overweight is 25.0–29.9, and obese is 30.0 and above for most UK adults. For South Asian, Chinese, Black African, and Black Caribbean adults, NICE recommends lower thresholds due to higher cardiovascular risk at lower BMI levels.
- Tier Approach: NICE endorses the UK's four-tier weight management pathway: tier 1 (self-help and community programmes), tier 2 (primary care), tier 3 (specialist multidisciplinary services), and tier 4 (bariatric surgery).
Check your BMI using our free BMI calculator above to understand where you fall within NICE-endorsed healthy weight ranges for the UK.
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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.
Accessing NICE Guidance and NHS Health Resources
NICE guidance is publicly available through nice.org.uk, where you can search for recommendations on weight management, nutrition, physical activity, and many other health topics. All NICE guidance is based on rigorous review of clinical evidence and is updated regularly as new research emerges.
Your GP can access NICE guidance to inform decisions about your care. If you're interested in weight loss injections, GLP-1 medications, or understanding your personal healthy weight, speak with your GP about NICE recommendations relevant to your situation. You can also use our free weight converter and GLP-1 weight loss calculator on this page to explore your options and prepare informed questions for your healthcare provider.
- 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 NICE stand for and what does it do?
NICE stands for the National Institute for Health and Care Excellence. It's an independent UK body that develops evidence-based guidance for the NHS, healthcare professionals, and social care providers. NICE reviews clinical research and produces recommendations on diagnosis, treatment, and prevention to help ensure high-quality, consistent care across the UK.
How do NICE guidelines affect weight management in the UK?
NICE provides guidance on obesity treatment and weight management that directly shapes NHS policy. This includes criteria for eligibility for prescription weight loss medications, the four-tier weight management pathway approach, and BMI thresholds. GPs and specialist services follow NICE guidance when assessing patients and deciding on treatment options.
What are NICE's BMI categories for adults in the UK?
According to NICE and NHS guidelines, healthy BMI is 18.5–24.9, overweight is 25.0–29.9, and obese is 30.0 and above for most UK adults. For South Asian, Chinese, Black African, and Black Caribbean adults, NICE recommends lower thresholds (healthy weight 18.5–22.9, overweight 23.0–27.4, obese 27.5 and above) due to higher health risks at lower BMI levels in these populations.
Where can I find NICE guidance on weight loss medications like Mounjaro and Wegovy?
NICE guidance on weight loss medications is available at nice.org.uk. You can search for "obesity" or "weight management" to find relevant recommendations. Your GP can also access this guidance. If you're considering these medications, speak with your GP about NICE eligibility criteria and whether prescription treatment is appropriate for your individual circumstances.
How do I use NICE guidance to support my personal health decisions?
While NICE guidance informs NHS practice, personal health decisions should always be made with your GP or healthcare provider. Use our free BMI calculator and weight converter above to understand your current health metrics within NICE-endorsed UK standards, then discuss your results and any concerns with your GP for personalised advice.
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.