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 Is Wegovy and How Does It Work in the UK?
Wegovy is a prescription-only weight management injection licensed in the UK for adults with obesity or overweight with weight-related health conditions. It contains semaglutide, a GLP-1 receptor agonist that helps reduce appetite and support weight loss alongside diet and physical activity. Understanding what Wegovy is, how it works, and whether you might be eligible under NHS guidelines is important before considering this treatment. This guide covers the UK prescribing context, NICE approval, and how to access Wegovy through the NHS or private routes.
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 Prescribing Pathway for Wegovy
Wegovy (semaglutide) was approved by NICE in 2021 and is now available through NHS specialist weight management services (tier 3) across the UK. NHS eligibility criteria include adults with a BMI of 30 kg/m² or above, or 25–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For South Asian, Chinese, Black African, and Black Caribbean adults, lower BMI thresholds may apply.
Access is through referral to your local specialist weight management service, not standard GP prescriptions. The STEP-1 clinical trial showed participants taking Wegovy lost an average of 14.9% of their body weight over 68 weeks alongside a reduced-calorie diet and increased physical activity. Regional NHS availability varies significantly — some areas have long waiting lists, while others have limited services. Your GP can refer you if you meet the criteria and explore what your local service offers.
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: Free at point of care through tier 3 services but involves referral, assessment, and potential waiting lists. Regional variation means some areas offer faster access than others.
Private route: Available through registered online prescribing services after a clinical consultation. Private Wegovy is faster to access but costs approximately £150–£250 monthly depending on dose. Both routes require a UK-licensed prescriber to assess your suitability. Use our free GLP-1 weight loss calculator to understand potential outcomes at different doses, and try our BMI calculator to check your eligibility criteria before speaking to your GP or a prescriber.
- 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 Wegovy the same as Ozempic?
Both contain semaglutide, but they are different products. Wegovy is licensed for weight management with a maximum dose of 2.4 mg weekly. Ozempic is licensed for type 2 diabetes (up to 2 mg weekly) and is not approved for weight loss in the UK. Using Ozempic for weight loss would be off-label prescribing.
What dose of Wegovy would I start on?
The starting dose is 0.25 mg once weekly. Over approximately 16 weeks, the dose increases gradually to a maintenance dose of 2.4 mg weekly. Your prescriber will adjust the dose based on your response and tolerance. Doses cannot be skipped — timing between injections should be at least 72 hours.
How long does it take to see results with Wegovy?
Most people begin noticing appetite changes within the first few weeks. Measurable weight loss typically becomes apparent after 4–8 weeks of consistent use. The clinical trial showed meaningful weight loss over 68 weeks, so it's a longer-term commitment. Individual results vary significantly based on diet, activity level, and personal metabolism.
Can I get Wegovy on the NHS in my area?
NHS availability depends on your local integrated care board (ICB) and regional specialist weight management services. Not all areas have equal access. Ask your GP about tier 3 services in your area, or contact your local NHS weight management service directly. Some regions have waiting lists of several months.
What are the main side effects of Wegovy in the UK?
The most common side effects are nausea, diarrhoea, vomiting, and constipation — usually mild and temporary. Less common side effects include headache, fatigue, and injection site reactions. Serious side effects are rare but can include pancreatitis (severe stomach pain) or gallbladder problems. Always report persistent or severe symptoms to your prescriber or GP. ```
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.