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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Wegovy Weight Loss Injection in the UK
Wegovy is a prescription-only weekly weight loss injection containing semaglutide, approved by the MHRA for weight management in UK adults. It works as a GLP-1 receptor agonist, helping reduce appetite and support sustainable weight loss when used alongside lifestyle changes. Access in the UK is through NHS specialist tier 3 weight management services or private online prescribing. This guide explains how Wegovy works, who's eligible, NHS prescribing pathways, and what to expect. Use our free GLP-1 weight loss calculator above to explore potential outcomes at different doses.
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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.
NHS Eligibility and NICE Guidance for Wegovy
NICE has approved semaglutide (Wegovy) for NHS use within specialist tier 3 weight management services. You may be eligible if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, NHS thresholds start at BMI 27.5 or above, reflecting higher health risks at lower weights.
- Tier 3 pathway: Referral from your GP to a specialist weight management service
- Assessment: Full health check, bloods, and suitability assessment
- Support: Medical supervision, dietitian input, and behaviour change support
- Waiting times: Vary by region; many areas have significant waiting lists (months to years)
Regional ICBs control availability. Not all areas have equal provision. Your GP can advise on local access and waiting times.
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: Getting Wegovy in the UK
NHS access offers medical support and monitoring but involves tier 3 referral and regional variation. Many areas have waiting lists exceeding 12 months.
Private access is available through GPhC-registered online prescribers without NHS referral. A clinical assessment determines suitability. Costs typically range from £130–£300 monthly depending on dose.
Both routes require a valid UK prescription and clinical assessment. Neither route assures prescription. Private access is faster (often within days) but involves direct cost. NHS access is free but dependent on local service availability and capacity. Use our BMI calculator above to check your starting eligibility, then discuss options with your GP or a licensed 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.
How does Wegovy work as a weight loss injection?
Wegovy contains semaglutide, a GLP-1 receptor agonist that mimics a natural gut hormone. It signals fullness to the brain, reduces appetite and food cravings, slows stomach emptying, and helps regulate blood sugar. These effects combine to support weight loss alongside a reduced-calorie diet and increased physical activity.
What weight loss can I expect with Wegovy?
Clinical trials (STEP-1) showed average weight loss of approximately 15% body weight at the highest dose (2.4 mg) over 68 weeks alongside lifestyle changes. Individual results vary significantly. Some people lose more, some less. Results depend on adherence, diet, activity, genetics, and other health factors.
How long does Wegovy treatment last?
Wegovy is ongoing treatment. You continue weekly injections as long as the medication helps and remains medically appropriate. If you stop Wegovy, lost weight may return over time. Long-term use is supported by NHS guidance for appropriate candidates. Your prescriber will monitor your progress regularly.
What are the main side effects of Wegovy?
Very common side effects include nausea, diarrhoea, vomiting, and constipation—usually mild and often improve over weeks. Common effects include indigestion, headache, fatigue, and injection site reactions. Serious side effects are rare but include severe stomach pain (pancreatitis), gallbladder problems, and serious allergic reactions. Always report unexpected symptoms to your prescriber.
Is Wegovy available on the NHS everywhere in the UK?
NICE has approved semaglutide for NHS use, but availability depends on your regional ICB (Integrated Care Board). Some areas have well-resourced tier 3 services; others have limited provision or significant waiting lists. Ask your GP about local availability, waiting times, and whether you meet regional eligibility criteria. Private access offers faster alternatives. ```
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.