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
Weight Loss Surgery Cost in the UK — And Prescription Alternatives
Weight loss surgery in the UK can cost between £5,000 and £15,000 privately, making it unaffordable for many. However, prescription weight management options like Mounjaro and Wegovy are now available through the NHS and private prescribing, offering a more accessible alternative for eligible adults. These GLP-1 injections can support meaningful weight loss at a fraction of surgical costs. Understanding your options — and whether you qualify — is the first step toward finding a solution that fits your health needs and budget.
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 Prescription Weight Loss Options
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are GLP-1 or GIP/GLP-1 receptor agonist injections that work by reducing appetite and helping you feel fuller after meals.
- Mounjaro: Once-weekly injection, doses 2.5mg–15mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks alongside diet and exercise.
- Wegovy: Once-weekly injection, doses 0.25mg–2.4mg. Average weight loss approximately 15% of body weight over 68 weeks in clinical trials.
- Saxenda: Daily injection, doses 0.6mg–3mg. Available longer in the UK; similar weight loss outcomes to Wegovy.
Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Individual results vary significantly. Our free GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
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 Access vs Private Prescribing — What Are Your Options?
NHS access: Weight loss medications are available through NHS specialist tier 3 and tier 4 weight management services. You'll need a GP referral and may face waiting lists of several months to years depending on your region. NHS treatment is free at the point of use.
Private prescribing: Available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. Costs typically range from £129–£320 per month depending on dose. This route is faster — often accessible within days — and doesn't require NHS referral.
Speak with your GP about your weight management goals. They can assess your eligibility, discuss whether prescription medication is appropriate for you, and explain both NHS and private pathways. Calculate your BMI using our free 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.
Is weight loss surgery available on the NHS?
Bariatric surgery is available on the NHS, but only for people with severe obesity (usually BMI 40+) and significant weight-related health complications, or BMI 35+ with serious health conditions. Long waiting lists are common. Private surgery costs £5,000–£15,000+. Prescription medications offer a less invasive, more affordable alternative for many people.
How much do GLP-1 weight loss injections cost privately in the UK?
Private GLP-1 medications typically cost £129–£320 per month depending on the dose and provider. Mounjaro and Wegovy are similarly priced. Costs are lower at starting doses and increase as you titrate upward. Many people find this more affordable than surgery or long-term weight management programmes.
Can I get Mounjaro or Wegovy on the NHS?
Yes. NICE has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) for NHS use within specialist weight management services. However, availability varies significantly by region, and waiting lists can be lengthy. Ask your GP about referral to your local specialist weight management service to explore NHS access.
Am I eligible for prescription weight loss medication?
You may be eligible if you have a BMI of 30 or above, or 27 or above with at least one weight-related health condition (type 2 diabetes, high blood pressure, cardiovascular disease, or obstructive sleep apnoea). A GP or licensed prescriber will assess your individual circumstances and medical history before prescribing.
How much weight will I lose with GLP-1 injections?
Clinical trials showed average weight loss of 15–21% of body weight over 68–72 weeks, but individual results vary significantly. Outcomes depend on dose, adherence, dietary changes, and physical activity. Our weight loss calculator can provide a personalised estimate based on your starting weight and medication dose.
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.