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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Weight Loss NICE CKS — Understanding UK Clinical Guidance
NICE Clinical Knowledge Summaries (CKS) provide evidence-based guidance for UK GPs and healthcare professionals on weight management and obesity. These guidelines outline when prescription weight loss medication may be appropriate, eligibility criteria based on BMI and health conditions, and the role of lifestyle changes alongside treatment. Understanding NICE CKS helps you know what to expect when discussing weight loss options with your GP and how the NHS structures weight management care across different tiers of service.
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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.
[H2]NICE CKS Weight Management Recommendations[/H2]
NICE CKS emphasises a stepped approach to weight management, starting with lifestyle interventions before considering prescription medication. For adults with a BMI of 30 or above—or BMI of 27 to 29.9 with weight-related health conditions like type 2 diabetes, hypertension, or cardiovascular disease—prescription weight loss medication may be considered as part of a comprehensive weight management uk programme. NICE recognises that GLP-1 receptor agonists (such as semaglutide in Wegovy) and dual GIP/GLP-1 agonists (tirzepatide in Mounjaro) are evidence-based options when used alongside a reduced-calorie diet and increased physical activity. The guidance stresses that these are prescription-only medicines requiring careful assessment by a healthcare professional, and that individual results vary significantly. NICE also notes that ethnicity-adjusted BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults, who may qualify for treatment at lower BMI levels due to higher health risks at these weights.
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.
[H2]NICE CKS Access and NHS Tier Structure[/H2]
NICE guidance is integrated into the NHS four-tier weight management pathway. Tier 1 involves self-help and community programmes; Tier 2 includes primary care interventions with your GP; Tier 3 is specialist multidisciplinary weight management services where prescription weight loss medication may be initiated; and Tier 4 covers bariatric surgery for severe obesity. Accessing prescription weight loss medication through the NHS typically requires referral to a Tier 3 specialist service, though availability and waiting times vary significantly by region. Use our free BMI calculator to check whether you may meet the initial eligibility criteria, and our GLP-1 weight loss calculator to explore potential outcomes. Always speak with your GP as the first step—they can assess your individual circumstances and discuss whether specialist referral is appropriate for you.
- 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 CKS say about weight loss injections?
NICE CKS recognises GLP-1 and GIP/GLP-1 medications as evidence-based options for weight management in eligible adults. These are prescription-only medicines to be used alongside lifestyle changes, with individual results varying. NICE guidance emphasises clinical assessment and careful monitoring by healthcare professionals.
Who qualifies for weight loss medication under NICE CKS guidance?
Adults with a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions, may be eligible. Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Specific eligibility is determined by a healthcare professional during clinical assessment.
Can I access weight loss medication through the NHS under NICE CKS?
Yes, through NHS specialist (Tier 3) weight management services. You'll typically need a GP referral. Availability and waiting times vary by region. Private prescription options are also available following online clinical assessment.
How do NICE CKS recommendations differ between Mounjaro and Wegovy?
Both are evidence-based options under NICE guidance. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. NICE recognises both as clinically appropriate for eligible individuals. A prescriber will assess which is suitable for you.
Does NICE CKS guidance mention bmi weight loss targets?
NICE focuses on sustainable weight loss of 0.5–1 kg per week alongside lifestyle changes. Clinical trials show prescription medications may help achieve 15–clinically studied weight loss on average. Results vary individually, and BMI reduction is just one outcome—health improvements matter too.
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.