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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Ozempic Injections for Weight Loss in the UK
Ozempic (semaglutide 2 mg) is primarily licensed in the UK for type 2 diabetes management, not weight loss. However, the same active ingredient is available as Wegovy (semaglutide 2.4 mg), which is UK-licensed specifically for weight management. This guide explains the difference, UK-licensed weight loss options, eligibility criteria, and how to discuss prescription weight loss medication with your GP. If you're interested in weight management injections, there are several effective alternatives approved for use in the UK.
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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.
UK-Licensed Weight Loss Injections and Ozempic
Ozempic is not licensed for weight loss in the UK — using it for this purpose is off-label prescribing. Instead, the UK has three licensed GLP-1 and dual-mechanism injections for weight management:
- Wegovy (semaglutide 2.4 mg) — GLP-1 injection, once weekly, up to 2.4 mg maximum dose
- Mounjaro (tirzepatide) — Dual GIP + GLP-1 injection, once weekly, up to 15 mg maximum dose
- Saxenda (liraglutide) — GLP-1 injection, once daily, up to 3 mg maximum dose
Clinical trials show these licensed options help eligible adults lose an average of 14–21% body weight alongside reduced-calorie diet and increased physical activity. Individual results vary significantly. These are prescription-only medicines requiring clinical assessment to determine suitability.
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 Access and How to Check Your Eligibility
Prescription weight loss medication in the UK is available through two routes: NHS specialist weight management services (tier 3/4) or private online prescribing. Eligibility generally requires: BMI of 30 or above, or 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply. Use our free BMI calculator above to check your starting point, then discuss options with your GP. Your GP can refer you to NHS specialist services if appropriate, or you can explore private prescribing following an online clinical assessment.
- 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 Ozempic the same as Wegovy?
Both contain semaglutide, but at different doses and for different purposes. Ozempic (up to 2 mg) is licensed for type 2 diabetes. Wegovy (up to 2.4 mg) is the UK-licensed weight management version. Using Ozempic for weight loss is off-label; Wegovy is the approved choice for weight management in the UK.
Can my GP prescribe Ozempic for weight loss?
Your GP cannot prescribe Ozempic for weight loss as it is not licensed for this use in the UK. However, they can refer you to NHS specialist weight management services or discuss licensed alternatives like Wegovy or Mounjaro. Private prescribers can also assess your eligibility for licensed weight loss medications.
What is the average weight loss with GLP-1 injections in the UK?
Clinical trials show average weight loss of 14–21% body weight depending on the medication and dose, achieved alongside reduced-calorie diet and increased physical activity. Individual results vary significantly. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
How do I know if I'm eligible for prescription weight loss medication on the NHS?
You generally need a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Ethnicity-adjusted thresholds may apply. Your GP can assess your eligibility and refer you to specialist tier 3 services if appropriate. Check your BMI using our free calculator on this page first.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management in the UK. Wegovy is a GLP-1 agonist (single mechanism), while Mounjaro is a dual GIP + GLP-1 agonist. Clinical trials show similar average weight loss (15–21%), but Mounjaro may work differently for some individuals. Your prescriber will help determine which is most appropriate 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.