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
10 Stone Weight Loss: UK Prescription Medication Options
Losing 10 stone (63.5kg) is a significant health goal that can meaningfully reduce your risk of type 2 diabetes, heart disease, and other weight-related conditions. If lifestyle changes alone haven't worked, prescription weight management medications are now available through the NHS and private prescribing in the UK. These medications work alongside diet and exercise to support sustainable weight loss. Our free GLP-1 weight loss calculator can help you explore potential outcomes with different treatment options, whilst our BMI calculator shows you where you are now and your healthy weight targets.
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.
UK-Licensed Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
Mounjaro is a dual GIP and GLP-1 receptor agonist given as a once-weekly injection. In clinical trials (SURMOUNT-1), participants lost an average of 15–21% of their body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity. At the 10mg dose, average weight loss was approximately 19.5%.
Wegovy (semaglutide) is a GLP-1 receptor agonist, also injected once weekly. Clinical trial data (STEP trials) showed average weight loss of around 14.9% over 68 weeks at the maximum 2.4mg dose.
Saxenda (liraglutide) is a daily injection with similar mechanisms. Individual results vary significantly based on adherence, diet, and lifestyle changes. All three require a prescription and clinical assessment from a qualified healthcare provider.
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.
NHS vs Private Access and Getting Started
NHS access: Prescription weight loss treatment is available through tier 3 specialist weight management services. You typically need a referral from your GP, and eligibility usually requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Waiting lists vary significantly by region.
Private access: You can access these medications through GPhC-registered online prescribing services following a clinical assessment, without waiting for NHS referral. Costs typically range from £129–£320 per month depending on the dose.
Next step: Speak with your GP about your weight loss goals. They can discuss whether prescription medication is appropriate for you, assess your eligibility, and explain what's available both on the NHS and privately. Use our BMI calculator above to understand your starting point.
- 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.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight with Mounjaro and around 15% with Wegovy when combined with diet and exercise. However, individual results vary significantly. Using our free GLP-1 weight loss calculator can give you a personalised estimate based on your current weight and starting point.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Your GP can assess your eligibility and refer you to a specialist weight management service if appropriate.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with higher average weight loss results (15–21%) in trials. Wegovy (semaglutide) is a single GLP-1 agonist with average weight loss around 15%. Both are once-weekly injections. Your prescriber will recommend the most suitable option for you.
Can I get these medications without going through the NHS?
Yes, you can access prescription weight loss medication through private online prescribing services in the UK if you meet clinical criteria. A licensed prescriber will assess you, and if appropriate, issue a prescription to be dispensed by a registered pharmacy.
Do I need to change my diet and exercise when taking these medications?
Yes. Prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They support your efforts by reducing appetite and helping you feel fuller, but they are not replacements for lifestyle changes.
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.