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
Wegovy Injections for Weight Loss in the UK
Wegovy is a prescription-only weekly weight loss injection licensed in the UK for adults with excess weight and weight-related health conditions. It contains semaglutide, a GLP-1 receptor agonist that works by helping reduce appetite and support feeling fuller after eating. Access through the NHS is available via tier 3 specialist weight management services, though availability varies significantly by region. Private prescription options are also available in the UK. Use our free GLP-1 weight loss calculator to explore how Wegovy might support your health goals, and our BMI calculator to assess your eligibility based on NHS guidelines.
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 UK Prescribing for Wegovy
NHS eligibility for Wegovy in the UK: You may be eligible if you have a BMI of 30 kg/m² or above, or BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, slightly lower BMI thresholds apply. NICE (National Institute for Health and Care Excellence) has approved semaglutide for use within NHS weight management services, but access is typically through specialist tier 3 services rather than standard GP prescription. Waiting times vary considerably: Some regions have lengthy waiting lists, whilst others offer swifter access. You must be referred by your GP to a tier 3 service for NHS assessment. Based on the STEP clinical trials, Wegovy helped participants lose an average of approximately 15% of their body weight over 68 weeks, though individual results vary significantly and weight loss is achieved alongside a reduced-calorie diet and increased physical activity.
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 Wegovy Access in the UK
NHS route: Your GP refers you to your local tier 3 specialist weight management service. Assessment happens through the NHS, and if approved, Wegovy is prescribed through specialist services. Costs are covered by the NHS if you meet criteria, but regional variation and waiting lists are significant factors. Private route: You can access Wegovy privately through UK-licensed prescribers via online consultations. A private prescription is issued if clinically appropriate, dispensed by GPhC-registered pharmacies. Private costs range from approximately £129–£200 per month depending on dose. Both routes require a clinical assessment confirming you are suitable for semaglutide. Track your progress with our free progress tracker once you begin treatment, or use our weight converter to monitor your results in both kg and stone.
- 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 the difference between Wegovy and Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes (doses up to 2mg) and is not approved for weight loss in the UK. Wegovy is the licensed weight management version (doses up to 2.4mg). Using Ozempic for weight loss would be off-label in the UK. Always use the medication prescribed for your specific condition.
How long does Wegovy take to work for weight loss?
Weight loss typically begins within the first few weeks, with most significant changes occurring between 8–16 weeks. The STEP trials showed continued weight loss over 68 weeks. However, individual response varies considerably. Your prescriber can monitor your progress and adjust your dose if needed.
Can I get Wegovy on the NHS if my BMI is 27?
If your BMI is 27–29.9, you may be eligible if you have at least one weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. For South Asian, Chinese, Black African, or Black Caribbean adults, eligibility may apply at slightly different thresholds. Your GP or specialist service will assess your individual circumstances.
What are the main side effects of Wegovy injections?
Most common side effects include nausea, diarrhoea, constipation, and stomach discomfort—usually mild and temporary. Serious side effects are rare but can include pancreatitis (severe stomach pain) or gallbladder problems. Always report any concerning symptoms to your healthcare provider or pharmacist immediately.
How does Wegovy compare to Mounjaro for weight loss?
Both are once-weekly injections, but Wegovy is a GLP-1 agonist, whilst Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist. In clinical trials, Mounjaro showed slightly higher average weight loss (~21% vs ~15%), but results vary significantly between individuals. Your prescriber will recommend the most appropriate option based on your health profile.
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.