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
What Does Wegovy Do? NHS and UK Health Context
Wegovy (semaglutide) is a prescription-only GLP-1 receptor agonist injection licensed in the UK for weight management in adults. It works by mimicking a natural hormone your gut produces after eating, helping to reduce appetite and support feeling fuller after smaller meals. In clinical trials, Wegovy helped people lose an average of around 15% of their body weight — though individual results vary significantly. Access in the UK is through NHS specialist weight management services or private prescribing following clinical assessment. Understanding how Wegovy works and who is eligible can help you make informed decisions about your weight health.
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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
Mechanism of action: Wegovy contains semaglutide, which activates GLP-1 receptors in your brain and gut. This single hormone pathway works by signalling fullness to your brain, reducing food cravings, and slowing how quickly food leaves your stomach — helping you feel satisfied with smaller portions.
NHS eligibility criteria: In the UK, you may be eligible for Wegovy through NHS tier 3 specialist weight management services if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or cardiovascular disease). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply — eligibility may start at BMI 27.5 or above.
- Clinical trial (STEP-1): 68 weeks on Wegovy 2.4mg showed approximately 14.9% average body weight loss
- Results achieved alongside reduced-calorie diet and increased physical activity
- Individual results vary based on genetics, adherence, and lifestyle factors
Access typically requires referral from your GP to a tier 3 service, though availability and waiting times vary significantly by region.
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: Wegovy is available through NHS specialist weight management services (tier 3) in some regions. You'll need a GP referral, clinical assessment, and monitoring by the specialist team. However, NHS availability is limited — many areas have significant waiting lists, and not all integrated care boards currently offer it.
Private route: Wegovy is available through GPhC-registered online pharmacies following a consultation with a UK-licensed prescriber. This route doesn't require NHS referral and is typically faster than NHS pathways. Private costs vary by dose and provider, usually ranging from £129–£250 per month depending on your dose stage.
- Both routes require a valid prescription from a UK-licensed prescriber
- Both involve clinical assessment of your eligibility and health
- Your GP can discuss which route is most appropriate for your circumstances
Try our free GLP-1 weight loss calculator to estimate potential results, and use our BMI calculator to understand your current health category.
- 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 (up to 2mg dose) whilst Wegovy is licensed for weight management in UK adults (up to 2.4mg dose). Wegovy is the licensed weight loss version. Using Ozempic for weight loss is off-label and not approved for this purpose in the UK.
How long does it take to see weight loss results with Wegovy?
Most people begin noticing appetite changes within the first 2–4 weeks. Measurable weight loss typically becomes apparent after 8–12 weeks of consistent use alongside lifestyle changes. Maximum benefit is usually seen around 16–20 weeks. Individual timelines vary significantly.
Can I get Wegovy on the NHS in my area?
NHS availability for Wegovy is limited and varies by region. Some integrated care boards offer it through tier 3 specialist weight management services, but many areas have waiting lists or don't currently provide it. Your GP can check what's available locally and discuss options with you.
What are the main side effects of Wegovy in the UK?
Common side effects include nausea, diarrhoea, constipation, and stomach pain — usually mild and temporary during dose adjustments. Injection site reactions can occur. Serious but rare side effects include pancreatitis symptoms (severe stomach pain). Always discuss any concerns with your prescriber.
Does Wegovy work better than diet and exercise alone?
Clinical trials show Wegovy, combined with diet and exercise, produces greater weight loss than diet and exercise alone. However, Wegovy works best alongside lifestyle changes, not as a replacement for them. Results vary widely between individuals based on genetics, adherence, and overall health.
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.