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 Injections: Wegovy in the UK
Wegovy (semaglutide) is a prescription-only weekly weight loss injection licensed in the UK for adults with excess weight and certain health conditions. It works as a GLP-1 receptor agonist, helping to reduce appetite and support feeling fuller after meals. Access to Wegovy in the UK varies depending on whether you pursue NHS or private routes, and understanding your eligibility under NICE guidance is the first step. Our free GLP-1 weight loss calculator can help you explore potential outcomes, whilst our BMI calculator lets you check where you currently stand against NHS health thresholds.
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.
NHS Eligibility and NICE Guidance for Wegovy
NICE has approved semaglutide (Wegovy) for use within NHS specialist weight management services. You are typically eligible for NHS-funded Wegovy if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² alongside at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or sleep apnoea).
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — eligibility may begin at BMI 27.5 or above, as these groups face higher cardiovascular and metabolic risks at lower weights.
Access to Wegovy through the NHS is via tier 3 specialist weight management services — not standard GP prescription. You typically need a GP referral to your local integrated care board's specialist service. However, NHS availability varies significantly by region, and waiting lists can be very long in many areas. Once prescribed, Wegovy is dispensed by NHS hospitals or accredited community pharmacies at no cost to you (beyond the standard prescription charge if eligible).
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.
Wegovy: NHS vs Private Access in the UK
NHS route: Free or low-cost (standard prescription charge), but requires GP referral and specialist tier 3 assessment. Waiting times vary from weeks to months or even longer depending on your local ICB. You will need regular monitoring and follow-up appointments.
Private route: Available through GPhC-registered online prescribers without NHS referral. You complete an online clinical assessment, and if approved, receive a prescription dispensed by a private pharmacy. Costs typically range from £129–£300 per month depending on dose. Results from the STEP trial showed semaglutide helped participants lose approximately 15% of body weight on average alongside diet and exercise — individual results vary significantly.
Whichever route you choose, Wegovy is always combined with lifestyle changes including a reduced-calorie diet and increased physical activity for best results.
- 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 Wegovy and how does it work for weight loss?
Wegovy (semaglutide) is a once-weekly injectable GLP-1 receptor agonist. It mimics a natural gut hormone that signals fullness to the brain, helps reduce appetite, and slows how quickly food leaves your stomach. Clinical trials showed it helps people lose weight when combined with diet and exercise, but individual results vary.
Am I eligible for Wegovy on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes or high blood pressure. Lower thresholds apply for South Asian, Chinese, Black African, and Caribbean adults. NHS access requires a GP referral to a tier 3 specialist weight management service in your area.
What's the difference between Wegovy and Mounjaro?
Wegovy (semaglutide) is a single GLP-1 agonist, whilst Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist. Mounjaro may produce slightly higher average weight loss in trials, but both require prescription and clinical assessment. Your prescriber will advise which is more suitable for you.
How much weight can I expect to lose with Wegovy?
Clinical STEP trials showed average weight loss of around 15% of body weight over 68 weeks on the maximum 2.4 mg dose, alongside a reduced-calorie diet and exercise. However, individual results vary significantly — some people lose more, some less. Your GP or prescriber can discuss realistic expectations for your situation.
How long does it take to access Wegovy through the NHS?
Waiting times vary by region. Some areas have waiting lists of several months or longer. Private access is typically faster — you can often be prescribed within 1–2 weeks of your online assessment. Either way, treatment requires a clinical assessment and prescription from a licensed UK healthcare professional.
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.