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 For Weight Loss in the UK
Wegovy (semaglutide) is a prescription-only, once-weekly weight loss injection licensed in the UK for adults with obesity or overweight with related health conditions. The medication works by activating GLP-1 receptors in the brain, helping reduce appetite and support feeling fuller after smaller meals. Access through the NHS is available via specialist tier 3 weight management services, though private online prescribing is also an option for eligible adults. Clinical trial data shows Wegovy can help achieve significant weight loss when combined with lifestyle changes.
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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 Access Routes for Wegovy
NHS eligibility for Wegovy: You may be assessed for Wegovy through NHS specialist weight management services if you have a BMI of 30 kg/m² or above, or 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). NICE has approved semaglutide as a treatment option within tier 3 services.
How to access via NHS: Your GP can refer you to your local integrated care board's (ICB) specialist weight management service. However, waiting times vary significantly by region—some areas have waiting lists of several months or longer. NHS access is typically reserved for those who have tried structured lifestyle approaches first.
STEP trial evidence: Clinical trials showed that adults on Wegovy lost an average of 14.9% of their body weight over 68 weeks, alongside a reduced-calorie diet and increased physical activity. Individual results vary considerably based on adherence and personal metabolism.
- Once-weekly injection administration
- Doses escalate from 0.25 mg to maximum 2.4 mg over 16 weeks
- Available on NHS through tier 3 specialist services only
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 in the UK
NHS route: Free at point of use but requires GP referral, specialist assessment, and often lengthy waiting times. Prescriber reviews and ongoing monitoring are provided through the NHS service. Private route: Available through GPhC-registered online pharmacies following a consultation with a UK-licensed prescriber. Private access is faster and doesn't require an NHS referral, but costs typically range from £130–£300 monthly depending on dose.
Both routes require a clinical assessment confirming you meet eligibility criteria and that Wegovy is appropriate for your individual health profile. Your prescriber will discuss semaglutide side effects, potential interactions with other medications, and whether this weekly weight loss injection aligns with your health goals.
Use our free BMI calculator above to check your personal BMI and understand where you currently fall within NHS eligibility ranges. Our GLP-1 weight loss calculator can also help project potential outcomes at different Wegovy doses.
- 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 are different products. Wegovy (up to 2.4 mg) is licensed specifically for weight management in UK adults. Ozempic (up to 2 mg) is approved for type 2 diabetes. Using Ozempic for weight loss would be off-label. Wegovy is the correct prescription weight loss version of semaglutide in the UK.
How quickly will I lose weight on Wegovy?
Weight loss typically begins within 2–4 weeks but varies individually. Clinical trials showed average loss of around 14.9% of body weight over 68 weeks. The NHS recommends losing 0.5–1 kg per week as a safe rate. Results depend on dose, diet adherence, exercise, and individual metabolism. Your prescriber will monitor your progress.
Can I get Wegovy on the NHS in my area?
Wegovy is available through NHS tier 3 specialist weight management services where NICE-approved. However, availability and waiting times vary significantly by integrated care board (ICB). Contact your GP to ask about referral options in your region, or check your local ICB website for service information and current waiting lists.
What are the most common side effects of Wegovy?
Very common side effects include nausea, diarrhoea, vomiting, and constipation—especially when starting or increasing doses. These often improve over time. Less common but serious side effects include severe stomach pain (possible pancreatitis) and gallbladder problems. Always report persistent or concerning symptoms to your prescriber immediately.
How does Wegovy compare to Mounjaro for weight loss?
Wegovy (GLP-1 agonist) and Mounjaro (GIP/GLP-1 dual agonist) are both licensed weekly injections in the UK. Clinical trials suggest Mounjaro may produce slightly greater average weight loss, but both are effective. Choice depends on individual health profile, tolerability, and prescriber assessment. Your doctor will advise which is most suitable for you.
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.