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
NICE Guidelines — UK Health Guidance for Weight and Wellness
The National Institute for Health and Care Excellence (NICE) is the independent organisation that develops evidence-based guidance for the NHS in England, Wales, and Northern Ireland. NICE guidelines shape how GPs, hospitals, and specialist services approach weight management, preventive care, and treatment decisions. Understanding NICE recommendations helps you make informed choices about your health alongside your healthcare provider.
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.
How NICE Guidance Influences UK Weight Management
NICE develops clinical guidelines based on the best available scientific evidence, clinical expertise, and patient experience. For weight management, NICE has published guidance on obesity prevention, bariatric surgery eligibility, and weight loss medication use in the NHS. NICE recommendations determine which treatments the NHS funds and how they're delivered through specialist tier 3 and tier 4 weight management services.
- NICE endorses BMI as a screening tool for health risk assessment, whilst acknowledging its limitations
- NICE recommends weight loss of 0.5–1 kg per week as sustainable and safe
- NICE guidance supports access to prescription weight loss injections for eligible adults within NHS services
- NICE recognises ethnicity-adjusted BMI thresholds for South Asian, Chinese, Black African, and Black Caribbean populations
NICE guidance is regularly updated as new clinical evidence emerges, ensuring NHS practice remains current and effective.
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.
NICE Guidance and Your Personal Health Decisions
While NICE guidelines inform NHS policy and GP practice, they don't replace individual clinical assessment. Your GP will consider NICE recommendations alongside your personal health history, current medications, and individual circumstances before recommending any treatment or lifestyle change. You can check your BMI using our free BMI calculator above to understand your starting point, and discuss the results with your GP in the context of NICE-recommended health thresholds. NICE guidance supports informed conversation between patients and their healthcare providers, helping you make choices aligned with current evidence.
- 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 NICE and why does it matter for UK health?
NICE (National Institute for Health and Care Excellence) is an independent UK organisation that produces evidence-based guidance for the NHS. NICE recommendations determine which treatments are funded by the NHS, how services are delivered, and what healthcare professionals recommend to patients. Following NICE guidance ensures NHS care is based on the latest research and clinical best practice.
Does NICE recommend weight loss medications like Mounjaro or Wegovy?
Yes. NICE has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) as options for weight management in eligible UK adults, typically those with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. These medications are prescribed through NHS specialist services following NICE-aligned assessment criteria.
What weight loss rate does NICE recommend?
NICE guidance recommends losing weight at a rate of 0.5–1 kg per week as safe and sustainable. This pace supports fat loss whilst preserving muscle mass and allows time for lifestyle changes to become established habits. Faster loss is possible under medical supervision but carries higher risks.
Does NICE guidance apply differently to different ethnicities?
Yes. NICE endorses the NHS guidance that adults of South Asian, Chinese, Black African, and Black Caribbean heritage have elevated health risks at lower BMI levels. NICE recommends adjusted BMI thresholds for these groups (typically starting at BMI 23 instead of 25 for overweight category), reflecting evidence that metabolic risk begins earlier.
How can I use NICE guidance when talking to my GP?
You can ask your GP whether their recommendations align with current NICE guidance on weight management, healthy BMI, or prescription treatments. NICE guidance supports informed discussion between you and your healthcare provider. Use our free weight converter and BMI calculator to understand your measurements in the context of NICE-recommended healthy weight ranges for UK adults.
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.