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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What You Need to Know About Wegovy in the UK
Wegovy (semaglutide) is a prescription-only weight management injection licensed in the UK for adults with obesity or overweight with related health conditions. This comprehensive guide covers NHS prescribing pathways, eligibility criteria, how the GLP-1 receptor agonist works, clinical trial results, and the difference between accessing Wegovy through specialist NHS services versus private online prescribing. Understanding your options helps you make an informed decision about whether this medication might be suitable for you.
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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.
How Wegovy Works and NHS Eligibility in the UK
Wegovy (semaglutide) is a GLP-1 receptor agonist — it works by activating the GLP-1 hormone pathway in your body, which helps regulate appetite and food cravings. The medication supports feeling fuller after smaller meals and slows how quickly food leaves your stomach. In 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.
UK eligibility criteria: You may be eligible for Wegovy if you have a BMI of 30 kg/m² or above (obesity), or a BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — eligibility may start at BMI 27.5 or above due to higher health risks at lower BMI levels in these populations. Check your personal BMI using our free BMI calculator above to see where you fall.
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 to Wegovy in the UK
NHS pathway: Wegovy is available through NHS specialist tier 3 weight management services following referral from your GP. NICE has approved semaglutide for use within the NHS, but access varies significantly by region and ICB (Integrated Care Board). Waiting lists for NHS specialist services can extend many months in some areas. Your GP will assess whether NHS referral is appropriate for your circumstances.
Private pathway: Wegovy is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route does not require NHS referral and can be faster, though costs typically range from £129–£250 per month depending on dose. Either route requires a prescription — Wegovy is not available over the counter. You can track your progress with our free progress tracker whether you choose NHS or private access.
- 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), while Wegovy is licensed specifically for weight management (doses up to 2.4mg). Using Ozempic for weight loss in the UK is off-label prescribing. Wegovy is the appropriate licensed medication for weight management in the UK.
How does Wegovy compare to Mounjaro?
Wegovy is a GLP-1 only agonist, while Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist. Clinical trials show Mounjaro achieved slightly higher average weight loss (15–21% vs Wegovy's ~15%), but both are effective. Individual results vary significantly, and the best choice depends on your specific health circumstances and clinical assessment.
What are the common side effects of Wegovy in the UK?
Very common side effects include nausea, diarrhoea, vomiting, and constipation — usually mild and often improving over time. Less common but serious side effects include severe stomach pain (possible pancreatitis), gallbladder problems, and allergic reactions. Always report persistent or concerning symptoms to your prescriber or GP.
How long does it take to see weight loss results with Wegovy?
Most people begin to notice weight loss within the first 4–8 weeks, though this varies. The medication works best alongside a reduced-calorie diet and increased physical activity. Full benefits typically develop over 16–20 weeks as you reach therapeutic doses. Our weight loss calculator can help estimate potential outcomes at different doses.
Can I get Wegovy on the NHS in my area?
NHS availability depends on your local ICB's funding and tier 3 specialist services capacity. Contact your GP to enquire about referral to your regional weight management service. If NHS waiting times are long, private online prescribing offers an alternative route, though this involves a cost.
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.