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 Loss Programme — What's Available in the UK
The NHS offers a structured weight management programme across four tiers, ranging from self-help digital tools to specialist services and bariatric surgery. If you're looking to lose weight in the UK, understanding how to access NHS support is the first step. This guide explains what's available, who qualifies, and how prescription weight loss medication like Mounjaro and Wegovy fits into the NHS weight management pathway. We'll also help you understand where your weight sits using our free BMI calculator and explore what realistic weight loss looks like.
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.
The Four Tiers of NHS Weight Management
The NHS organises weight loss support into four progressive tiers, each designed to meet different needs:
- Tier 1: Self-help through digital tools, community programmes, and free online resources like the NHS Weight Loss Plan. This is where most people start.
- Tier 2: Primary care-based interventions delivered by your GP or practice nurse, including behaviour change support and structured weight loss programmes.
- Tier 3: Specialist multidisciplinary weight management services. This is where prescription weight loss medication—including Mounjaro (tirzepatide) and Wegovy (semaglutide)—may be offered following clinical assessment.
- Tier 4: Bariatric surgery for severe obesity with significant health complications, accessed through specialist NHS centres.
Most people progressing through weight management in the UK start at Tier 1 or 2. Referral to Tier 3 specialist services is typically made by your GP if lifestyle changes alone are insufficient and you meet eligibility criteria. Access varies by region and available NHS resources.
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.
Prescription Weight Loss Medication on the NHS
NHS prescription eligibility: You may be eligible for prescription weight loss medication on the NHS if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds applied.
GLP-1 medications like Wegovy support weight loss by reducing appetite and helping you feel fuller after smaller meals. Clinical trials showed participants lost an average of 15% of body weight—though individual results vary. Access through the NHS typically involves referral to a Tier 3 specialist service, assessment, and prescription if appropriate. Waiting times vary significantly by region. Alternatively, prescription weight loss medication is available privately through online prescribing following a clinical assessment. Use our GLP-1 weight loss calculator to explore potential outcomes at different treatment levels.
---COL_J_ALTERNATIVE---How weight loss medication works: GLP-1 receptor agonists like Wegovy (semaglutide) are prescription-only injections that activate natural appetite-control hormones. They're given once weekly and work alongside a reduced-calorie diet and increased physical activity. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist—a newer option that works on two hormone pathways.
Both medications help reduce cravings and support sustainable weight loss when used as part of a comprehensive approach. Individual results vary; some people lose more weight than others. Eligibility for NHS prescription requires assessment by a weight management specialist. Your GP can refer you to these services, though waiting lists vary by region. If NHS waiting times are long, private online prescribing is another route after clinical assessment by a UK-licensed prescriber.
- 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.
Can I get weight loss injections on the NHS?
Yes, GLP-1 medications like Wegovy and Mounjaro are available on the NHS through Tier 3 specialist weight management services. You'll need referral from your GP, a BMI of 30+ (or 27+ with weight-related health conditions), and assessment by a specialist. Access and waiting times vary significantly by region.
What is the NHS Weight Loss Plan?
The NHS Weight Loss Plan is a free digital Tier 1 programme offering 12 weeks of guided support. It includes calorie tracking, physical activity guidance, and behaviour change strategies. It's available online and is often the first step for people starting their weight loss journey through the NHS.
How much weight will I lose with prescription medication?
Clinical trials show GLP-1 medications help people lose an average of 15% of body weight when combined with diet and exercise—though individual results vary significantly. Some lose more, some less. Your GP or specialist can discuss realistic expectations based on your personal health.
What's the difference between Tier 2 and Tier 3 NHS weight management?
Tier 2 is primary care-based (your GP practice) and focuses on lifestyle changes and behaviour support. Tier 3 is specialist multidisciplinary services where prescription medications may be offered. You typically progress to Tier 3 if Tier 2 interventions alone haven't worked or your BMI/health needs require specialist assessment.
Is weight loss medication available privately if NHS waiting times are long?
Yes. Private online prescribing is available in the UK through GPhC-registered pharmacies. You'll have a clinical assessment with a UK-licensed prescriber; if approved, medication is dispensed by post. Costs typically range from £129–£320 per month depending on dose. Both NHS and private options require prescription and clinical assessment.
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.